Vitamins & Supplements · Formula
Energy and Focus Blends (Gummies, Drinks, Powders and Shots)
Caffeine-based energy and focus blends · also called Energy drinks, energy shots, focus gummies, energy powders, mezclas para energía y concentración
Energy and focus blends mix caffeine with B vitamins, taurine, sugar, herbs and amino acids, and are sold as gummies, drinks, powders and shots. Caffeine is the main active ingredient. Evidence for the finished products is limited: drinks and shots may help short-term alertness, but benefits from the other ingredients are not shown and no trial of focus gummies or powders was found. Heart, label-accuracy and caffeine-total cautions matter most.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Energy and Focus Blends (Gummies, Drinks, Powders and Shots)
Energy and focus blends are caffeine-based products with added ingredients. Evidence for the finished product is limited and mostly credits caffeine. The cautions are about total caffeine, the heart, hidden amounts and young people.
What these products are and who they are sold to
Energy and focus blends are drinks, shots, gummies and powders sold to improve energy, focus or alertness. In a 2022 analysis of the 75 top-selling US energy drinks and shots, products had about 18 ingredients each. Teens and young adults are major buyers (MedlinePlus).
Energy drinks were not sold as dietary supplements; the shots were. No analysis of the label contents of focus gummies or powders was found.
What is usually inside
Caffeine was in every product analysed (average 174.4 mg). Vitamin B6 was in 72%, vitamin B3 and B12 in 67% each, vitamin B5 in 37.3% and taurine in 37.3%. Many B vitamins were far above the Daily Value. The ISSN also lists guarana, ginseng, carnitine, choline, tyrosine and L-theanine among common ingredients.
See the pages on caffeine, vitamin B6, vitamin B12, niacin, taurine and L-theanine linked below.
Reading the label
A serving is the amount the label says to use once, and amounts are per serving. '% Daily Value' compares an amount with a reference daily amount; a figure of several hundred percent means far more than that reference.
A 'proprietary blend' may list ingredients without each one's amount; 15 of 75 products used these. The FDA says caffeine need only be listed as an ingredient when added, and that many supplements state the amount voluntarily.
What the research shows
No trial of a finished focus gummy or powder was found. Expert reviews say energy drinks and shots can improve short-term alertness and aerobic performance, mostly through caffeine. Benefits of taurine, B vitamins and herbs are not shown, and results from one ingredient should not be added up as if the mix had been tested.
Caffeine alone is reported to help attention in most people. L-theanine with caffeine gave small differences with wide uncertainty.
At a glance
Traditional uses history, not proof
- Modern manufactured products; no traditional use
- Caffeine itself comes from plants such as coffee and tea
Studied for research
- Alertness and focus from drinks and shots, low certainty
- Caffeine alone for attention, moderate certainty
- Exercise performance with caffeine drinks, moderate certainty
- L-theanine with caffeine, low certainty
- Guarana and taurine additions, low or very low certainty
- B vitamins for energy, insufficient evidence
Main compounds
- Caffeine
- B vitamins (B6, B3, B12, B5)
- Taurine
- Guarana
Common forms
- Gummies
- Ready-to-drink energy drinks
- Energy shots
- Powders
Research links: 2022 label analysis of 75 energy drinks and shots · 2023 expert position stand on energy drinks and shots · 2025 review: energy drinks and the cardiovascular system (37 studies) · 2026 American Heart Association statement on caffeine · FDA: how much caffeine is too much · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Energy and focus blends (gummies, drinks, powders and shots)
- Common names
- Energy and focus blends (English); Energy drinks and energy shots (English); Focus gummies (English); Pre-workout style energy powders (English); Mezclas para energía y concentración (Spanish); Bebidas y shots energéticos (Spanish); Gomitas para la concentración (Spanish)
- Family or group
- A product type: mixes of caffeine with B vitamins, taurine, sugar, herbs or amino acids, sold as gummies, drinks, powders and shots.
- Harvest and processing
- In the 2022 label analysis, energy drinks were ready-to-drink beverages not sold as dietary supplements, and energy shots were small ready-made drinks sold as dietary supplements. How gummies and powders are made was not read from a source.
- Look-alikes and adulterants
- Name: Pre-workout supplements; Note: Caffeine-based powders for exercise; lab studies of their caffeine labels are cited on the Safety tab.; Name: Caffeine pills and pure caffeine powder; Note: Single-ingredient caffeine; the FDA warns against pure or highly concentrated powder. Has its own page.; Name: Multivitamins and B complex products; Note: Share B vitamins but are not sold for energy and focus in the same way. Have their own pages.
- Sustainability and conservation
- Not assessed.
What is inside, and how it may work
What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Caffeine | stimulant (methylxanthine) | Occurs naturally in coffee, tea and other plants; also added in pure form In 100% of 75 energy drinks and shots; average 174.4 mg per product | The main active ingredient; stimulates the central nervous system (MedlinePlus). 6 4 | Human data |
| Vitamin B6 (pyridoxine) | B vitamin | In 72% of products; average 366.9% of the Daily Value | Helps the body use energy from protein and carbohydrates (NHS). Not shown to add energy beyond that. 6 19 | Label analysis |
| Vitamin B3 (niacin) | B vitamin | In 67% of products; average 121.4% of the Daily Value | Normal role in using energy from food; high doses can cause flushing. 6 19 | Label analysis |
| Vitamin B12 | B vitamin | In 67% of products; average 5,244.5% of the Daily Value | No effect on cognition or depression in people without deficiency in a 16-trial review. 6 11 | Human data |
| Vitamin B5 (pantothenic acid) | B vitamin | In 37.3% of products; average 113.6% of the Daily Value | Normal metabolic role; no benefit from extra shown in sources read. 6 | Label analysis |
| Taurine | amino-acid-like compound | In 37.3% of products; amounts undisclosed | Caffeine plus taurine did not improve repeat sprints in one small trial. 6 8 | Human data |
| Guarana | plant extract containing caffeine | Seed Prevalence not stated in the abstract; listed by the ISSN among common ingredients | A very small effect on reaction speed in a pooled review. 7 5 | Human data |
| Other listed ingredients | mixed | Mixed The ISSN lists ginseng, carnitine, choline, vitamin C, vitamin A (beta carotene), vitamin D, electrolytes, sugars, tyrosine and L-theanine, with prevalence from 1.3% to 100% across ingredients | Many have not been studied alone or in combination. 7 | Expert review |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Central nervous system stimulation | Not specified in the sources read | MedlinePlus says caffeine stimulates the central nervous system, which can make you feel more awake and give a boost of energy; it also acts as a diuretic and increases stomach acid. 17 | Reference page |
| Normal B vitamin role in energy metabolism | Not specified in the sources read | The NHS says vitamin B6 helps the body use and store energy from protein and carbohydrates. This is a normal role and not shown to be boosted by extra supplements. 19 | Reference page |
Absorption, metabolism and elimination
- Absorption
- Within one hour of eating or drinking caffeine it reaches its peak level in the blood (MedlinePlus).
- Distribution
- MedlinePlus says caffeine passes through the placenta to the baby and a small amount passes into breast milk.
- Metabolism
- The FDA says there is wide variation in how fast people eliminate caffeine; the ISSN says genes affect response.
- Elimination
- Effects may last four to six hours (MedlinePlus).
- Bioavailability
- Not compared across gummies, drinks, powders and shots in the sources read.
Isolated compounds versus whole extracts
Finished blends combine ingredients that are mostly tested one at a time. The ISSN stand says many ingredients and combinations in energy drinks and shots have not been studied, and that added benefits of other nutrients remain to be determined. Foods and drinks that naturally contain caffeine, such as coffee, differ from added caffeine only in their other ingredients: the FDA says the body handles natural and added caffeine the same.
Nutritional composition
Typical caffeine per 12-fluid-ounce drink (FDA): caffeinated soft drinks 23 to 83 mg, green tea 37 mg, black tea 71 mg, regular brewed coffee 113 to 247 mg, energy drinks 41 to 246 mg. The NHS lists about 100 mg in a cup of instant coffee, 75 mg in a cup of tea and 80 mg in a 250 ml can of energy drink. These are nutrient facts, not advice. Amounts for B vitamin foods were not read.
2 moderate certainty3 low certainty1 very low certainty1 not enough evidence
What was looked at
The 7 benefits and uses checked for Energy and Focus Blends (Gummies, Drinks, Powders and Shots), each with how strong the evidence is. Tap one to open it.
- Alertness and focus from energy drinks and shotsLow certainty
- Caffeine on its own: attention and vigilanceModerate certainty
- L-theanine with caffeine (a common focus pairing)Low certainty
- Guarana in focus productsLow certainty
- Exercise performance with energy drinks and shotsModerate certainty
- Taurine added to caffeine (repeat sprints)Very low certainty
- B vitamins in 'energy' blendsNot enough evidence
Lab markers tracked in the studies
Reaction time on thinking testsAccuracy on attention tasksPeak power in repeated sprintsTiredness scores (unexplained fatigue)
What is Energy and Focus Blends (Gummies, Drinks, Powders and Shots) good for?
The main studied uses and how strong the human evidence is. Most trials test caffeine or one added ingredient by itself, not the finished product.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Alertness and focus from energy drinks and shots
Low certaintyAn expert review says energy drinks and shots taken before exercise can improve mental focus and alertness, and credits mostly the caffeine. It says benefits from the other ingredients in the product are not shown. No trial of a finished focus gummy or powder was found.
2 studiesProducts differ widely. Studied amounts are in the studies table.
Studies, doses and limits
What the trials found
The International Society of Sports Nutrition 2023 position stand reviewed energy drinks and shots. It says they can improve mental focus and alertness when taken 10 to 60 minutes before exercise, and that the main active ingredient is caffeine (and sugar). It says possible added benefits of other ingredients are still to be determined, and that many ingredient combinations have not been studied. MedlinePlus says there are limited data that energy drinks might temporarily improve alertness. In the 2022 label analysis, products were sold as improving energy, focus or alertness. No trial of a focus gummy or powder was read.
Results
Low certainty for finished drinks and shots, mostly from expert consensus. Insufficient for gummies and powders.
Effect sizes as reported
Not given. The position stand is a consensus statement, not a pooled analysis.
Why this rating
Rated low because the main source is an expert consensus rather than trials of the exact products, benefit is credited to caffeine, and the position stand authors report ties to sports supplement companies. Not rated lower for drinks because caffeine's effect on alertness is well described.
Form and dose studied
Products differ widely. Studied amounts are in the studies table.
Who was studied
Mostly healthy adults and athletes; teens and young adults are the main buyers.
Limits
Few trials of the finished product, and the other ingredients are untested in combination. Results for drinks do not carry over to gummies or powders.
Why researchers looked
These products are sold to improve energy, focus or alertness, so researchers asked whether the finished products do that.
Proposed mechanism Reference page
Not tested for the finished products. MedlinePlus says caffeine stimulates the central nervous system, which can make you feel more awake.
A proposed mechanism does not show that the effect happens in people.
Caffeine adds up across products and raises heart rate and blood pressure. See the Safety tab.
Caffeine on its own: attention and vigilance
Moderate certaintyCaffeine alone, the usual main ingredient, is reported to help attention and vigilance in most people. This is about caffeine itself, not about the finished blend.
1 studiesCaffeine alone in capsules, drinks, gum and other forms. Studied amou…
Studies, doses and limits
What the trials found
The 2021 ISSN position stand on caffeine says caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals, and may improve cognitive and physical performance in some people who are sleep-deprived. It also says responses and side effects such as poor sleep or anxiety differ between people and may relate to genes and usual caffeine intake.
Results
Reported benefit in most people for attention and vigilance, from an expert review of caffeine research.
Effect sizes as reported
Not given in the abstract.
Why this rating
Moderate because the position stand reviewed many trials of caffeine and calls the benefit consistent. Not rated higher because it is a consensus statement from authors with supplement-industry ties and the abstract gives no effect sizes.
Form and dose studied
Caffeine alone in capsules, drinks, gum and other forms. Studied amounts are in the studies table.
Who was studied
Trained and untrained healthy people.
Limits
About caffeine, not blends. Tolerance, genes and usual intake change response.
Why researchers looked
Caffeine is in every product in the 2022 label analysis, so what it does by itself explains most of what the blends do.
Traditional use
Caffeine occurs naturally in more than 60 plants including coffee beans and tea leaves (MedlinePlus).
Proposed mechanism Reference page
MedlinePlus says caffeine stimulates the central nervous system. A detailed mechanism was not read.
A proposed mechanism does not show that the effect happens in people.
Side effects of caffeine include jitters, poor sleep and fast heart rate. See the Safety tab.
L-theanine with caffeine (a common focus pairing)
Low certaintyA 2025 review of randomised trials found small-to-moderate differences in reaction time, attention and mood favouring theanine plus caffeine over placebo in the first two hours. The uncertainty around many results was wide.
1 studiesTheanine and caffeine given together in trials; amounts are in the st…
Studies, doses and limits
What the trials found
The review pooled trials among 50 randomised trials in healthy people (15 eligible for at least one meta-analysis). At 1 and 2 hours after theanine plus caffeine, small-to-moderate differences favoured the combination: choice reaction time, digit vigilance accuracy, attention switching accuracy and overall mood. Several confidence intervals reached zero. Theanine alone gave a small-to-moderate advantage on choice reaction time at 1 hour.
Results
Small short-term differences with uncertainty. The trials tested theanine and caffeine, not finished gummies, drinks or powders.
Effect sizes as reported
Choice reaction time SMD -0.48 (95% CI -1.01 to 0.05); digit vigilance accuracy 0.20 (0.02 to 0.38); attention switching accuracy 0.33 (0.13 to 0.54); mood 0.26 (-0.10 to 0.63).
Why this rating
Low because intervals are wide, outcomes were short-term and measured in labs, and the review was partly funded by a tea company.
Form and dose studied
Theanine and caffeine given together in trials; amounts are in the studies table.
Who was studied
Healthy adults.
Limits
Short-term outcomes only; none for everyday focus or finished products.
Why researchers looked
Many focus gummies and powders pair caffeine with L-theanine, an amino acid from tea, to take the edge off caffeine.
Traditional use
L-theanine is found in tea leaves.
Proposed mechanism Not established
Not established in the sources read.
A proposed mechanism does not show that the effect happens in people.
Caffeine's cautions apply. See the Safety tab.
Guarana in focus products
Low certaintyA 2023 pooled review of 8 placebo-controlled studies found guarana gave a very small average effect on thinking tests. Reaction time was a little faster; accuracy was not better.
1 studiesGuarana alone, not a finished blend. Amounts are in the studies table.
Studies, doses and limits
What the trials found
Eight placebo-controlled studies (328 people) gave a less-than-trivial average effect (Hedges g 0.076). Response time was faster (g 0.202) but accuracy was not different (g -0.077). Guarana in liquid tended to differ from capsules for response time.
Results
Very small effect on reaction speed; no effect on accuracy.
Effect sizes as reported
Overall g 0.076, p = 0.14; response time g 0.202, p = 0.005; accuracy g -0.077, p = 0.4.
Why this rating
Low because the review had only 8 studies with different guarana and caffeine amounts, and the effect cannot be separated from the caffeine inside guarana.
Form and dose studied
Guarana alone, not a finished blend. Amounts are in the studies table.
Who was studied
Healthy adults in short-term studies.
Limits
Guarana adds caffeine, which counts toward total caffeine.
Why researchers looked
Guarana is a plant source of caffeine and is added to many energy and focus products.
Traditional use
Guarana is a plant ingredient (Paullinia cupana) used in energy products.
Proposed mechanism Not established
The authors say it is unknown whether the effects come from caffeine or from other substances in guarana.
A proposed mechanism does not show that the effect happens in people.
The FDA notes guarana can be a source of caffeine in a product's total.
Exercise performance with energy drinks and shots
Moderate certaintyCaffeine, the main ingredient, improves exercise performance in many studies, and energy drinks with enough caffeine can help short-term aerobic performance. Added benefit from the other ingredients is not shown.
2 studiesMostly drinks and shots. Studied amounts are in the studies table.
Studies, doses and limits
What the trials found
The 2023 ISSN position stand says energy drinks can improve acute aerobic performance, largely depending on the amount of caffeine, and that taken 10 to 60 minutes before exercise they can improve focus, alertness, anaerobic and endurance performance. It says the main ergogenic ingredients are caffeine and carbohydrate, and the benefit of other nutrients in combination is still to be determined. The 2021 ISSN caffeine stand says energy drinks and pre-workout products with caffeine improved aerobic and anaerobic performance. MedlinePlus says there are limited data that energy drinks might temporarily improve physical endurance and not enough evidence that they enhance strength or power.
Results
Moderate for caffeine-containing drinks on short-term aerobic performance; credit goes to caffeine, not the other ingredients.
Effect sizes as reported
Small to moderate benefits for caffeine (position stand). No product-level effect sizes in the abstracts.
Why this rating
Moderate because two consensus statements agree on caffeine, but authors report supplement-industry ties, the evidence is mainly for caffeine, and MedlinePlus calls the data limited.
Form and dose studied
Mostly drinks and shots. Studied amounts are in the studies table.
Who was studied
Healthy adults and athletes.
Limits
Applies to short-term exercise in healthy people, not to everyday energy or to gummies and powders.
Why researchers looked
Energy products are sold to athletes and gym-goers for stamina and power.
Traditional use
These are modern manufactured products with no traditional use.
Proposed mechanism Expert consensus
Not established for the blends. The position stands credit mainly caffeine, and carbohydrate where sugar is present.
A proposed mechanism does not show that the effect happens in people.
Heart rate and blood pressure rise after energy drinks. See the Safety tab.
Taurine added to caffeine (repeat sprints)
Very low certaintyOne small crossover trial of 11 young men found caffeine plus taurine did not improve repeat sprints, and may have caused more fatigue by the last sprint.
2 studiesCapsule with caffeine and taurine; amounts in the studies table.
Studies, doses and limits
What the trials found
In 11 young men, 80 mg caffeine plus 1 g taurine in a capsule was compared with placebo one hour before ten 6-second cycle sprints. Peak power was about the same. Fatigue within a sprint was likely slightly greater at sprint 10, baseline heart rate was likely much higher, and blood lactate rose more after sprints 5 and 10.
Results
Null or slightly negative for sprint performance. The ISSN stand says the additive benefit of other ingredients remains to be determined.
Effect sizes as reported
Heart rate effect size 0.94 at baseline; peak power difference likely trivial.
Why this rating
Very low because it is one small trial in 11 men using a capsule, not a drink.
Form and dose studied
Capsule with caffeine and taurine; amounts in the studies table.
Who was studied
Young men.
Limits
Only one dose, one test and 11 people.
Why researchers looked
Taurine appears in 37.3% of energy drinks and shots in the 2022 label analysis, so researchers tested the caffeine and taurine amounts found in popular drinks.
Traditional use
These are modern manufactured products with no traditional use.
Proposed mechanism Not established
Not established.
A proposed mechanism does not show that the effect happens in people.
Higher heart rate was seen in the trial.
B vitamins in 'energy' blends
Not enough evidenceB vitamins have a normal job in using energy from food, which is why labels say 'supports energy'. A 2021 review of 16 trials found vitamin B12 did not improve thinking or mood in people who were not B12-deficient, and there was too little data on tiredness.
2 studiesB12 alone or in a B complex. Studied amounts vary by trial.
Studies, doses and limits
What the trials found
The 2021 review (16 randomised trials, 6,276 people without B12 deficiency or advanced neurological disease) found no effect of B12 alone or B complex on cognitive function and no overall effect on depression scores. Only one study reported on unexplained fatigue, so no analysis was possible. Trials of finished energy blends with B vitamins were not found. Deficiency is a separate case: the review does not apply to people who are deficient.
Results
Insufficient evidence that extra B vitamins add energy in people who already get enough.
Effect sizes as reported
No effect on cognition or depression; fatigue not analysable.
Why this rating
No trial of a finished blend was found, and fatigue could not be pooled. The review was well designed for cognition and mood, where it found no effect.
Form and dose studied
B12 alone or in a B complex. Studied amounts vary by trial.
Who was studied
Adults without overt B12 deficiency.
Limits
About B12 and B complex, not the finished product. Does not apply to deficiency.
Why researchers looked
B vitamins are in most energy products: vitamin B6 in 72%, B3 and B12 in 67% each, in the 75-product label analysis, often at many times the Daily Value.
Traditional use
These are modern manufactured products with no traditional use.
Proposed mechanism Reference page
The NHS says vitamin B6 helps the body use and store energy from protein and carbohydrates in food. That is a normal role, not proof that extra B vitamins add energy.
A proposed mechanism does not show that the effect happens in people.
High B6 can harm nerves (NHS). See the Safety tab.
Connections to the rest of health
How Energy and Focus Blends (Gummies, Drinks, Powders and Shots) connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Energy Vitality | Low certainty | Alertness and focus from energy drinks and shots: An expert review says energy drinks and shots taken before exercise can improve mental focus and alertness, and credits mostly the caffeine. It says benefits from the other ingredients in the product are not shown. No trial of a finished focus gummy or powder was found. | 7 6 | |
| Focus Memory | Low certainty | Alertness and focus from energy drinks and shots: An expert review says energy drinks and shots taken before exercise can improve mental focus and alertness, and credits mostly the caffeine. It says benefits from the other ingredients in the product are not shown. No trial of a finished focus gummy or powder was found. | 7 6 | |
| Focus Memory | Moderate certainty | Caffeine on its own: attention and vigilance: Caffeine alone, the usual main ingredient, is reported to help attention and vigilance in most people. This is about caffeine itself, not about the finished blend. | 4 | |
| Focus Memory | Low certainty | L-theanine with caffeine (a common focus pairing): A 2025 review of randomised trials found small-to-moderate differences in reaction time, attention and mood favouring theanine plus caffeine over placebo in the first two hours. The uncertainty around many results was wide. Guarana in focus products: A 2023 pooled review of 8 placebo-controlled studies found guarana gave a very small average effect on thinking tests. Reaction time was a little faster; accuracy was not better. | 12 5 | |
| Stress Relaxation | Low certainty | L-theanine with caffeine (a common focus pairing): A 2025 review of randomised trials found small-to-moderate differences in reaction time, attention and mood favouring theanine plus caffeine over placebo in the first two hours. The uncertainty around many results was wide. | 12 | |
| Endurance Support | Moderate certainty | Exercise performance with energy drinks and shots: Caffeine, the main ingredient, improves exercise performance in many studies, and energy drinks with enough caffeine can help short-term aerobic performance. Added benefit from the other ingredients is not shown. | 7 4 | |
| Physical Stamina | Moderate certainty | Exercise performance with energy drinks and shots: Caffeine, the main ingredient, improves exercise performance in many studies, and energy drinks with enough caffeine can help short-term aerobic performance. Added benefit from the other ingredients is not shown. | 7 4 | |
| Physical Stamina | Very low certainty | Taurine added to caffeine (repeat sprints): One small crossover trial of 11 young men found caffeine plus taurine did not improve repeat sprints, and may have caused more fatigue by the last sprint. | 8 6 | |
| Energy Vitality | Not enough evidence | B vitamins in 'energy' blends: B vitamins have a normal job in using energy from food, which is why labels say 'supports energy'. A 2021 review of 16 trials found vitamin B12 did not improve thinking or mood in people who were not B12-deficient, and there was too little data on tiredness. | 11 6 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Nervous System | Biological association | Low certainty | Studied for: Alertness and focus from energy drinks and shots Studied for: Caffeine on its own: attention and vigilance | 7 6 4 12 5 11 |
| Muscular System | Biological association | Moderate certainty | Studied for: Exercise performance with energy drinks and shots Studied for: Taurine added to caffeine (repeat sprints) | 7 4 8 6 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Cardiac arrhythmia | Adverse effect or risk | Systematic review and narrative review | Energy drinks are linked to rhythm disturbances and ECG changes in young people, with rare cardiac arrest reports. Energy drinks are linked to rhythm disturbances and ECG changes in young people. Preparation or compound: Energy drinks |
9 2 |
| Peripheral neuropathy | Adverse effect or risk | Regulator statement | The NHS says 200 mg or more of B6 a day can cause numbness in the arms and legs. The NHS says 200 mg or more of vitamin B6 a day can cause numbness in the arms and legs. Preparation or compound: High-dose vitamin B6 |
19 |
| Caffeine overdose | Adverse effect or risk | Regulator statement | The FDA is aware of at least two deaths linked to pure caffeine products. Preparation or compound: Pure and highly concentrated caffeine |
16 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Reaction time on thinking tests | Biological association | Low certainty | Measured in trials: slightly faster. A lab change is not the same as a health benefit. | 12 5 |
| Accuracy on attention tasks | Biological association | Low certainty | Measured in trials: mixed (a little better with theanine plus caffeine; no difference with guarana). A lab change is not the same as a health benefit. | 12 5 |
| Peak power in repeated sprints | Biological association | Very low certainty | Measured in trials: no clear change. A lab change is not the same as a health benefit. | 8 |
| Tiredness scores (unexplained fatigue) | Biological association | Not enough evidence | Measured in trials: could not be judged. A lab change is not the same as a health benefit. | 11 |
K. Biological pathways
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Caffeine | Preliminary mechanism | Human | The main active ingredient in nearly every product analysed. | 6 |
| Vitamin B6 | Preliminary mechanism | Reference page | Common in blends; high amounts can harm nerves. | 19 |
| Taurine | Preliminary mechanism | Human | In 37.3% of energy drinks and shots. | 6 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Caffeine | Biological association | Human | The main active ingredient; stimulates the central nervous system (MedlinePlus). Preparation or compound: Occurs naturally in coffee, tea and other plants; also added in pure form |
6 4 |
| Vitamin B6 (pyridoxine) | Biological association | Label analysis | Helps the body use energy from protein and carbohydrates (NHS). Not shown to add energy beyond that. | 6 19 |
| Vitamin B3 (niacin) | Biological association | Label analysis | Normal role in using energy from food; high doses can cause flushing. | 6 19 |
| Vitamin B12 | Biological association | Human | No effect on cognition or depression in people without deficiency in a 16-trial review. | 6 11 |
| Vitamin B5 (pantothenic acid) | Biological association | Label analysis | Normal metabolic role; no benefit from extra shown in sources read. | 6 |
| Taurine | Biological association | Human | Caffeine plus taurine did not improve repeat sprints in one small trial. | 6 8 |
| Guarana | Biological association | Human | A very small effect on reaction speed in a pooled review. Preparation or compound: Seed |
7 5 |
| Other listed ingredients | Biological association | Expert review | Many have not been studied alone or in combination. Preparation or compound: Mixed |
7 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).
Evidence at a glance: what the research found for 7 outcomes
Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.
The evidence
The research centre for Energy and Focus Blends (Gummies, Drinks, Powders and Shots). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing energy and focus formula summary, then re-read the FDA, MedlinePlus and NHS pages and the PubMed abstracts for every review, trial, statement and lab study cited. Only abstracts were read for studies. The NIH Office of Dietary Supplements pages were blocked and are marked unread.
Study library: every study we checked 19
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Ajibo 2024 Consumption of energy drinks by children and young people: a systematic review examining evidence of physical effects and consumer attitudes. Public Health · PMID 38228408 · DOI |
Systematic review |
57 studies of children and young people up to age 21 (weak studies were excluded) | Energy drinks Ready-to-drink beverages Varied · vs Varied |
Energy drink use was associated with smoking, alcohol, binge drinking and other substance use, short sleep, poor sleep quality, low academic performance, psychological distress, ADHD symptoms, insulin resistance and tooth erosion. The authors say more long-term studies are needed to show cause and suggest the precautionary principle for sales to this group. Associations, not cause (Not applicable) Methods, limits and fundingOutcomes: Health, behaviour and school outcomes linked to energy drink use Limitations: Mostly observational, so energy drinks may not be the cause. English-language studies from 2016 to July 2022. Funding and conflicts: No conflict statement in the record read. Read: abstract |
| Constantinou 2026 Energy Drinks and Arrhythmias in Adolescents and Young Adults: A Narrative Review of the Last Decade. Medicina (Kaunas) · PMID 42654430 · DOI |
Narrative review |
22 studies of adolescents and young adults: 10 randomised trials, 5 non-randomised trials, 1 observational study and 6 case reports | Energy drinks Ready-to-drink beverages Varied by study Varied by study · vs Varied by study |
Reported events included atrial fibrillation, ventricular fibrillation and, rarely, cardiac arrest, often after moderate-to-high intake. Experiments showed QTc changes of 6 to 20 ms, more extra beats from the upper heart chambers, and heart rate changes of 3 to 10 beats per minute. Most changes were short-lived and reversible. The authors say energy drinks may raise arrhythmia risk in young people. QTc 6 to 20 ms; heart rate 3 to 10 beats per minute (experimental studies) (Not given in the abstract) Methods, limits and fundingOutcomes: Arrhythmias and ECG changes Limitations: Narrative review, so study selection is not systematic. Little on frequent use, long-term outcomes or less-studied ingredients. Funding and conflicts: The authors declare no conflicts of interest. Read: abstract |
| Desbrow 2019 Caffeine content of pre-workout supplements commonly used by Australian consumers. Drug Test Anal · PMID 30196576 · DOI |
Laboratory analysis n/a |
15 15 popular pre-workout supplements sold in Australia, tested within and between batches |
Pre-workout supplements (caffeine content tested) Powders and similar products · vs Label claims |
Caffeine ranged from 91 to 387 mg per serving. Only 6 of the 15 labels stated caffeine. Measured caffeine was 59% to 176% of packaging claims. All but one product varied by 40 mg or more per serving within or between batches. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Measured caffeine per serving compared with the label Limitations: Pre-workout supplements, not focus gummies or energy shots; 15 products in one country. Funding and conflicts: No conflict statement in the record read. Read: abstract |
| Guest 2021 International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr · PMID 33388079 · DOI |
Position stand |
Published research on caffeine and exercise and cognition, in trained and untrained people | Caffeine on its own, energy drinks and pre-workout products Capsules, gum, drinks and other forms Doses of 3 to 6 mg per kg body mass were consistently effective in the stand's review Acute (single use) · vs Placebo |
Caffeine improved exercise performance in many but not all studies. The stand says caffeine has been ergogenic for cognitive function, including attention and vigilance, in most people, and may help some people when sleep-deprived. Side effects on sleep or anxiety differ between people and may relate to genes and usual intake. Energy drinks and pre-workout products with caffeine were shown to improve aerobic and anaerobic performance. Small to moderate benefits for performance (Not applicable) Methods, limits and fundingOutcomes: Exercise performance, cognition, side effects Limitations: An expert consensus, not a new trial. About caffeine itself, not finished blends. Funding and conflicts: Several authors report ties to sports supplement companies and the society has received grants from companies selling caffeine products. Read: abstract |
| Hack 2023 Effect of Guarana (Paullinia cupana) on Cognitive Performance: A Systematic Review and Meta-Analysis. Nutrients · PMID 36678305 · DOI |
Systematic review meta analysis |
328 8 placebo-controlled studies, 328 participants |
Guarana (Paullinia cupana), one dose Capsule or dissolved in liquid; guarana 37.5 to 500 mg containing 4.3 to 100 mg caffeine Guarana 37.5 to 500 mg (reported caffeine 4.3 to 100 mg) Single (acute) dose · vs Placebo |
Overall effect was less than trivial (Hedges g 0.076, p = 0.14). Response time was faster than placebo (g 0.202, p = 0.005); accuracy was not different (g -0.077, p = 0.4). Dose and timing were not related to effect. The authors say it is unknown whether the effect comes from the caffeine or from other substances in guarana. Hedges g 0.076 overall; 0.202 response time; -0.077 accuracy (Not given in the abstract) Methods, limits and fundingOutcomes: Cognitive task performance (response time and accuracy) Limitations: Small number of studies with different doses and tests. Guarana on its own, not in a finished blend. Funding and conflicts: No conflict of interest declared; no funding received. Read: abstract |
| Jagim 2022 Prevalence and Amounts of Common Ingredients Found in Energy Drinks and Shots. Nutrients · PMID 35057494 · DOI |
Label analysis n/a |
75 The 75 top-selling US energy products on retail websites as of September 2021: 55 energy drinks and 20 energy shots |
Nutrition fact panels of energy drinks and energy shots Ready-to-drink beverages; drinks not sold as supplements, shots sold as supplements |
Products had 18.2 ingredients on average (SD 5.7). Fifteen products used proprietary blends with undisclosed ingredient amounts. Caffeine was in all products (average 174.4 mg, SD 81.1). Vitamin B6 was in 72% (average 366.9% of the Daily Value), B3 in 67% (121.4%), B12 in 67% (5,244.5%), B5 in 37.3% (113.6%). Taurine was in 37.3%, amounts undisclosed. The authors say many formulas had B vitamins well above the recommended daily value. Descriptive only; no health outcomes (Not applicable) Methods, limits and fundingOutcomes: Number of ingredients per product; which ingredients were most common and in what label amounts Limitations: Looks at labels, not lab-tested contents. Covers drinks and shots only; no gummies or powders. US products in 2021. Funding and conflicts: The authors declare no conflict of interest. Read: abstract |
| Jagim 2023 International society of sports nutrition position stand: energy drinks and energy shots. J Int Soc Sports Nutr · PMID 36862943 · DOI |
Position stand |
Published research on energy drinks and shots in exercise, metabolism and cognition | Energy drinks and energy shots Ready-to-drink beverages and shots The stand links benefit to caffeine above about 3 mg per kg body weight (over 200 mg) Acute (10 to 60 minutes before exercise) · vs Placebo or other drinks |
Energy drinks can improve acute aerobic performance, largely by the amount of caffeine. The stand says the ergogenic value of caffeine is well established, but possible added benefits of other nutrients in the products remain to be determined, and that many ingredients are unstudied or unstudied in combination. It lists ingredients including caffeine, taurine, ginseng, guarana, carnitine, choline, B vitamins, vitamin C, electrolytes, sugars, tyrosine and L-theanine, with prevalence from 1.3% to 100%. It advises caution for adolescents, and says the products are not recommended for children aged 2 to 12, pregnancy, trying to conceive, breastfeeding or caffeine-sensitive people, and that people with heart, metabolic, liver, kidney or nerve disease or on affected medicines should talk to a physician. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Aerobic and anaerobic performance, focus, alertness, safety Limitations: An expert consensus, not a new trial. Says many product combinations have not been tested. Funding and conflicts: No potential conflict of interest was reported. Read: abstract |
| Jeffries 2020 Energy Drink Doses of Caffeine and Taurine Have a Null or Negative Effect on Sprint Performance. J Strength Cond Res · PMID 29065052 · DOI |
Randomised crossover trial |
11 11 men, age 21 plus or minus 2 |
Caffeine plus taurine Gelatin capsule Caffeine 80 mg and taurine 1 g (amounts in popular energy drinks) Single dose, 1 hour before 10 x 6-second cycle sprints · vs Placebo (maltodextrin, about 1 g) |
Peak power was likely trivially different. Fatigue within a sprint was likely slightly greater in the caffeine and taurine condition at sprint 10. Baseline heart rate was likely much higher (effect size 0.94) and blood lactate rose more after sprints 5 and 10. Perceived exertion was unchanged. The authors concluded no improvement in repeat-sprint cycling and perhaps more fatigue. Heart rate effect size 0.94 at baseline (Not given in the abstract) Methods, limits and fundingOutcomes: Peak power, fatigue, heart rate, blood lactate, perceived exertion Limitations: Only 11 young men and one dose. Used capsules, not a drink, and magnitude-based inference rather than standard tests. Funding and conflicts: No conflict statement in the record read. Read: abstract |
| Mandato 2025 The Effects of Energy Drinks on the Cardiovascular System: A Systematic Review. Curr Cardiol Rep · PMID 41236610 · DOI |
Systematic review |
1597 37 studies, 1,597 participants aged 13 or older (mean age 22.6); Red Bull and Monster were the most studied brands |
Energy drinks Ready-to-drink beverages Varied by study Varied by study · vs Varied by study |
Heart rate rose in 60.9% of studies, systolic blood pressure in 53.8%, diastolic blood pressure in 61.5% and QTc interval length in 63.2%. Other ECG changes (PR interval, T-wave) appeared in 57.9% of studies. The authors conclude energy drinks raise heart rate, blood pressure and QTc. Percent of studies reporting each change (not size of change) (Not given in the abstract) Methods, limits and fundingOutcomes: Heart rate, blood pressure, ECG changes Limitations: Counts studies rather than pooling effect sizes. The abstract does not say how long changes lasted. Mostly young adults. Funding and conflicts: No competing interests declared. Read: abstract |
| Marcus 2026 Caffeine and Cardiovascular Disease: A Scientific Statement From the American Heart Association. Circulation · PMID 42473796 · DOI |
Scientific statement n/a |
Published research on caffeine and heart and metabolic health, mostly on coffee | Caffeine from natural sources and in pure form Mostly coffee; some energy drinks Varied Varied · vs Varied |
Most research is observational and focused on coffee. The statement says data on high caffeine amounts such as those in energy drinks are limited and generally suggest cardiovascular harm. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Blood pressure, diabetes, lipids, coronary disease, heart failure, atrial fibrillation, stroke Limitations: An expert statement, not a new trial. Energy drink data are limited. Funding and conflicts: No conflict statement in the record read. Read: abstract |
| Markun 2021 Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression. Nutrients · PMID 33809274 · DOI |
Systematic review meta analysis |
6276 16 randomised trials, 6,276 participants without overt B12 deficiency or advanced neurological disease |
Vitamin B12 alone, or B complex (B12 with folic acid, with or without B6) Supplements Varied by trial Varied by trial · vs Placebo |
No evidence of an effect of B12 alone or B complex on any area of cognitive function, and no overall effect on depression scores. Only one study reported effects on unexplained fatigue, so no analysis was possible. The authors say B12 is likely ineffective for cognition and depression in people without advanced neurological disorders. No effect (Not given in the abstract) Methods, limits and fundingOutcomes: Cognitive function, depressive symptoms, unexplained fatigue Limitations: Fatigue could not be analysed. About B12 alone or in B complexes, not finished energy blends. Does not apply to people who are B12 deficient. Funding and conflicts: The authors declare no conflict of interest. Read: abstract |
| Payne 2025 Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutr Rev · PMID 40314930 · DOI |
Systematic review meta analysis |
50 randomised trials in healthy people; 15 were eligible for at least one meta-analysis | L-theanine plus caffeine; L-theanine alone; tea Supplements and tea Varied by trial Mostly single doses; outcomes at 1 and 2 hours · vs Placebo |
After theanine plus caffeine, small-to-moderate differences favoured the combination at 1 and 2 hours: choice reaction time SMD -0.48 (95% CI -1.01 to 0.05), digit vigilance accuracy 0.20 (0.02 to 0.38), attention switching accuracy 0.33 (0.13 to 0.54), overall mood 0.26 (-0.10 to 0.63). Theanine alone favoured choice reaction time at 1 hour (SMD -0.35, -0.61 to -0.10). The authors note the confidence intervals often show uncertainty about direction and size. SMD -0.48 to 0.33 (see results) (Several intervals include zero) Methods, limits and fundingOutcomes: Cognition, mood, sleep Limitations: Wide uncertainty; short-term outcomes; tested theanine and caffeine, not finished focus blends. Funding and conflicts: One author's PhD studentship is funded by Lipton Teas and Infusions; two authors are employees of Lipton or Unilever (tea companies). Read: abstract |
| Thompson 2025 Pediatric Exposures Associated with Caffeine Energy Products Reported to United States Poison Centers, 2011-2023. J Med Toxicol · PMID 39890754 · DOI |
Poison centre data analysis |
32482 32,482 single-substance caffeine energy product exposures in people under 20, reported to US poison centers |
Caffeine energy products (liquids, powders, solids) Beverages, shots, powders and granules, solid forms 2011 to 2023 · vs Other formulations |
Exposure rate rose 17.3% over the period. 69.6% were under 6 years old. 80.7% were not treated in a healthcare facility and 1.6% were medically admitted. Teenagers 13 to 19 were much more likely than younger children to be admitted (odds ratio 12.74) or have a serious outcome (18.83). Solid forms were more likely to have serious outcomes (odds ratio 1.98). Exposures to powders and granules rose 632.9% while shots fell 86.1%. Odds ratio 12.74 admission and 18.83 serious outcome for teens vs under 13 (95% CI 10.40 to 15.60 and 16.88 to 21.01) Methods, limits and fundingOutcomes: Who was exposed, to what form, and how serious the outcome was Limitations: Voluntary reports; shows exposures, not how often harm happens among all users. Many exposures in young children are accidental. Funding and conflicts: The authors declare no conflicts of interest. Read: abstract |
| da Costa 2022 Pre-workout supplements marketed in Brazil: Caffeine quantification and caffeine daily intake assessment. Drug Test Anal · PMID 33835708 · DOI |
Laboratory analysis n/a |
52 52 pre-workout supplements sold in Brazil |
Pre-workout supplements (caffeine content tested) Commercial products · vs Label claims |
Of 36 labels that stated a caffeine amount, 7 (19%) had more than 120% of the stated amount and 15 (42%) had less than 80%. Six products contained caffeine that was not declared. Five products would exceed 400 mg a day if used as the label directs. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Measured caffeine compared with the label Limitations: Pre-workout supplements in one country, not focus gummies or shots. Funding and conflicts: No conflict statement in the record read. Read: abstract |
| s-fda-caffeine FDA consumer update: Spilling the Beans: How Much Caffeine is Too Much? · Source |
Regulator or agency page n/a |
Methods, limits and fundingRead: page | ||
| s-fda-pure-caffeine FDA warns consumers about pure and highly concentrated caffeine · Source |
Regulator or agency page n/a |
Methods, limits and fundingRead: page | ||
| s-medlineplus-caffeine MedlinePlus: Caffeine · Source |
Regulator or agency page n/a |
Methods, limits and fundingRead: page | ||
| s-nhs-pregnancy-caffeine NHS: Foods to avoid in pregnancy (caffeine section) · Source |
Regulator or agency page n/a |
Methods, limits and fundingRead: page | ||
| s-nhs-vitamin-b NHS: Vitamin B (B6 and niacin sections) · Source |
Regulator or agency page n/a |
Methods, limits and fundingRead: page |
What we do not know yet
- No trial of a finished focus gummy or focus powder was found in the sources read.
- No trial of a finished blend with B vitamins was found.
- The NIH ODS fact sheets (upper limits for vitamin B6 and niacin) could not be read.
- No label analysis or lab test of focus gummies or focus powders was found; the label analysis covers drinks and shots only.
- No interaction study of a finished blend with blood pressure or heart rhythm medicines was found.
- No survey of heavy metals or contaminants in these products was read.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Other 4
Reaction time on thinking tests
Slightly faster in trials
How fast a person answers a simple screen task. Faster is better, as long as accuracy holds.
Low certaintyResults and what it means
Why it was measured
To see whether caffeine-based ingredients speed up mental responses.
Statistical vs. clinical meaning
Small short-term gains in lab tests; not shown in finished products or everyday life.
Safety implication
Caffeine from all products counts toward the day's total.
Accuracy on attention tasks
Mixed (a little better with theanine plus caffeine; no difference with guarana) in trials
How many answers are right on a screen test of attention, such as watching for a target.
Low certaintyResults and what it means
Why it was measured
Faster answers are less useful if they are wrong more often.
Statistical vs. clinical meaning
Accuracy gains were small and depended on the ingredient.
Safety implication
No safety problem was reported in the abstracts.
Peak power in repeated sprints
No clear change in trials
The highest power a cyclist produces in short, hard sprints.
Very low certaintyResults and what it means
Why it was measured
To see whether caffeine plus taurine improves sprint ability.
Statistical vs. clinical meaning
One small trial; no benefit shown.
Safety implication
Heart rate and blood lactate were higher.
| Study | Result | People | Product |
|---|---|---|---|
| 8 | Peak power likely trivially different; greater fatigue at sprint 10 | 11 young men | Caffeine 80 mg plus taurine 1 g |
Tiredness scores (unexplained fatigue)
Could not be judged in trials
Questionnaires about feeling tired when no cause such as deficiency has been found.
Not enough evidenceResults and what it means
Why it was measured
To see whether B vitamins reduce tiredness in people who are not deficient.
Statistical vs. clinical meaning
Cannot say whether B vitamins reduce tiredness.
Safety implication
Not applicable.
| Study | Result | People | Product |
|---|---|---|---|
| 11 | Only one of 16 trials reported fatigue, so no analysis was possible | 6,276 people in 16 trials | Vitamin B12 alone or B complex |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 6
- Caffeine adds up across drinks, shots, gummies, powders, pills and medicines. The FDA says caffeine can be added to energy bars, ice cream, gum, dietary supplements and over-the-counter medicines, and that the body handles added and natural caffeine alike. It cites 400 mg a day as an amount not generally associated with negative effects for most adults, and says what is 'too much' varies with body weight, medicines, health conditions and sensitivity. In the 2022 label analysis every one of the 75 energy drinks and shots had caffeine (average 174.4 mg). Check every product you use, not just one. Regulator statement and label analysis 15 6
- Pure and highly concentrated caffeine powders can kill. The FDA recommends avoiding dietary supplements of pure or highly concentrated caffeine and says it knows of at least two deaths in otherwise healthy people. It says one teaspoon of pure powdered caffeine is about the caffeine in 28 cups of coffee. Some pure and highly concentrated caffeine products remain on the market (FDA 2024). Regulator statement 16 15
- Energy drinks raise heart rate, blood pressure and QTc, and are linked to arrhythmias in young people. A 2025 systematic review of 37 studies (1,597 people, mean age 22.6) found heart rate rose in 60.9% of studies, blood pressure in about 54% to 62%, and QTc in 63.2%. A 2026 review of 22 studies in adolescents and young adults reported atrial and ventricular fibrillation and, rarely, cardiac arrest, mostly short-lived changes. The American Heart Association 2026 statement says data on high caffeine amounts such as those in energy drinks are limited and generally suggest cardiovascular harm. People with heart rhythm problems or high blood pressure should ask a doctor first. Systematic review, narrative review and scientific statement 9 2 10
- Label amounts may be wrong or hidden. In the 75-product label analysis, 15 products used proprietary blends that did not state ingredient amounts. In lab tests of pre-workout supplements, caffeine measured 59% to 176% of the label in Australia (15 products, only 6 labels stated caffeine), and in Brazil 42% of 36 labelled products had under 80% of the stated caffeine, 19% had over 120%, and 6 products had caffeine that was not declared. These tests were of pre-workout powders, not gummies or shots, so they show the risk but do not describe every product. Label analysis and laboratory analyses 6 3 14
- Children and teens: the FDA advises against energy drinks. The FDA says medical experts advise against energy drinks for children and teens because of sugar and caffeine, and that too much caffeine can cause fast heart rate, palpitations, high blood pressure, anxiety, sleep and digestive problems. A 2024 review of 57 studies linked energy drink use in young people with short sleep, poor sleep quality, substance use and other problems (these are associations). US poison centers received 32,482 reports about caffeine energy products in people under 20 between 2011 and 2023, mostly in children under 6; teens had far higher odds of serious outcomes. Regulator statement, systematic review and poison centre data 15 1 13
- High B6 from stacked products can damage nerves. The NHS says 200 mg or more of vitamin B6 a day can cause a loss of feeling in the arms and legs (peripheral neuropathy), which usually improves after stopping but can be permanent in a few cases. In the 75-product analysis vitamin B6 averaged about 367% of the Daily Value, and several products had much more. Check B6 across all your products, including multivitamins, and ask a pharmacist. Regulator statement and label analysis 19 6
Side effects 8
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Higher heart rate The 2026 review gives heart rate changes of 3 to 10 beats per minute in experiments. | Reported in 60.9% of 37 studies of energy drinks | Mild to moderate; may matter more with heart disease Mostly short-lived in experimental studies | Systematic review 9 2 |
| Higher blood pressure MedlinePlus also says caffeine increases blood pressure. | Systolic rose in 53.8% and diastolic in 61.5% of studies | Mild to moderate Not stated in the abstract | Systematic review 9 17 |
| QTc prolongation and other ECG changes; arrhythmias QTc changes of 6 to 20 ms were seen in experimental studies. | QTc longer in 63.2% of studies; arrhythmia events including atrial and ventricular fibrillation and rare cardiac arrest in a narrative review | Can be serious Most changes were acute and reversible | Systematic review, narrative review and case reports 9 2 |
| Restlessness, shakiness, anxiety, headaches, dizziness, upset stomach MedlinePlus says caffeine increases stomach acid and can cause heartburn. | Not stated | Mild to moderate Usually settles as caffeine wears off | Regulator statements 17 15 |
| Sleep problems Caffeine peaks within an hour and effects can last four to six hours (MedlinePlus). In young people, energy drink use is associated with short sleep and poor sleep quality, which does not prove cause. | Not stated | Mild to moderate Usually reversible | Regulator statements and systematic review of associations 17 1 |
| More fatigue and heart rate in repeated sprints with caffeine plus taurine Small trial; not proof of a general effect. | Seen in one trial of 11 men | Mild Short-term | Randomised crossover trial 8 |
| Numbness in arms and legs from high vitamin B6 NHS says 200 mg or more a day can cause it. | Not stated | Can be permanent in a few cases Usually improves after stopping | Regulator statement 19 |
| Skin flushing from high nicotinic acid (niacin) From the NHS niacin section. | Not stated | Mild; high amounts taken for a long time could damage the liver Not stated | Regulator statement 19 |
Liver
The NHS says taking high doses of nicotinic acid supplements for a long time could damage the liver. No liver injury from finished energy or focus blends was found in the sources read. A liver-safety database was not searched. 19
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Energy and Focus Blends (Gummies, Drinks, Powders and Shots) supports liver health.
Medicines and supplements 6
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Caffeine from other sources (coffee, tea, pills, pre-workout, medicines) supplement | Amounts add up, and added and natural caffeine act alike. | Total caffeine can pass the amount the FDA cites for most adults without anyone noticing. | Regulator statement High certainty 15 18 | Add up caffeine from every source and ask a pharmacist. |
| Guarana and other plant caffeine sources inside a blend supplement | Guarana contains caffeine. | The FDA says most US energy drinks list the total caffeine from all sources including guarana, but supplements may not, and the 2022 analysis found some products with undisclosed blend amounts. | Regulator statement and label analysis Moderate certainty 15 6 5 | Check whether the label states total caffeine. |
| Alcohol food | Caffeine can interfere with the ability to recognise how drunk you are. | MedlinePlus says combining alcohol and caffeine is dangerous. | Regulator statement Moderate certainty 17 | Do not mix; ask a doctor. |
| Stimulants, certain antibiotics, asthma medicines and heart medicines prescription | MedlinePlus lists these as medicines to check with a provider for interactions with caffeine. | The page lists them as medicines to check about; it does not name specific harmful pairs. | Regulator statement Moderate certainty 17 | Ask a doctor or pharmacist before use. |
| Blood pressure or heart rhythm medicines prescription | Not found for finished blends. | No interaction study of an energy or focus blend with these medicines was read. | Absence of evidence Not enough evidence | Absence of a study is not proof of safety. Ask a doctor or pharmacist. |
| Other B vitamin products and multivitamins supplement | Same nutrient from several products adds up. | B6 at 200 mg or more a day from supplements can harm nerves (NHS). Whether typical stacking reaches this was not studied. | Regulator statement Moderate certainty 19 6 | Check B6 across all products; ask a pharmacist. |
Who should check first 5
| Situation | Advice | Evidence |
|---|---|---|
| Pregnancy, trying to become pregnant, or breastfeeding | The NHS (reviewed June 2026) says not to have more than 200 mg of caffeine a day in pregnancy. The FDA and MedlinePlus advise talking to a provider. The ISSN stand does not recommend energy drinks and shots in pregnancy or breastfeeding. Ask a doctor first. | Regulator statements and position stand 18 15 17 7 |
| Children and teens | The FDA says experts advise against energy drinks for children and teens. The ISSN stand says not recommended for ages 2 to 12 and calls for caution in adolescents. Keep products with caffeine away from young children. | Regulator statements, position stand and poison centre data 15 7 13 |
| Heart rhythm problems, high blood pressure, anxiety, sleep disorders, migraines or reflux | MedlinePlus lists these as reasons to check with a health care provider before using caffeine. | Regulator statement 17 |
| Diabetes and weight concerns with sugary products | MedlinePlus says sugary energy drinks can contribute to weight gain and worsen diabetes; the ISSN stand says people with diabetes or heart, metabolic, liver, kidney or nerve disease should speak to a physician. Sugar-free products were not covered in the sources read. | Regulator statement and position stand 17 7 |
| People sensitive to caffeine | The ISSN stand says products are not recommended for caffeine-sensitive people. The FDA says sensitivity varies widely. | Position stand and regulator statement 7 15 |
Overdose, product quality and regulators
Summary. Caffeine overdose is the main danger. The FDA says toxic effects such as seizures can occur with rapid consumption of about 1,200 mg of caffeine, less than half a teaspoon of pure caffeine. Symptoms of overdose include a rapid or dangerously erratic heartbeat, seizures, vomiting, diarrhea, stupor and disorientation, and can end in death.
Animal. Not reviewed.
High dose or long term signals. Long-term safety of daily use of energy or focus blends was not found in the sources read.
Overdose response. Call poison help or emergency services (see urgent signs).
Genotoxicity. Not researched.
Quality problems found in the sources are about label accuracy and hidden or undeclared amounts. No survey of heavy metals or microplastics in energy or focus gummies, drinks, powders or shots was read.
Proprietary blends. 15 of 75 energy drinks and shots used proprietary blends with undisclosed ingredient amounts. 6
Caffeine label accuracy (Australia, pre-workout). Measured caffeine was 59% to 176% of packaging claims across 15 products; only 6 labels stated caffeine; 14 of 15 varied by 40 mg or more per serving within or between batches. 3
Caffeine label accuracy (Brazil, pre-workout). Of 36 labels with a caffeine amount, 15 (42%) had under 80% and 7 (19%) over 120% of the stated amount; 6 products had undeclared caffeine. 14
Energy shot sold as supplement vs drink. In the label analysis, drinks were not sold as dietary supplements and shots were. 6
| Body | Action | Date |
|---|---|---|
| US FDA (United States) | Cites 400 mg of caffeine a day as an amount not generally associated with negative effects for most adults; says experts advise against energy drinks for children and teens; says caffeine is listed on labels only if added as an ingredient, and supplements may give amounts voluntarily; says toxic effects such as seizures can occur with rapid consumption of about 1,200 mg. source | 2024-08-28 |
| US FDA (United States) | Recommends avoiding dietary supplements of pure or highly concentrated caffeine; aware of at least two deaths; one teaspoon of pure powder is about 28 cups of coffee. source | 2018-04-13 |
| MedlinePlus (US National Library of Medicine) (United States) | Says up to 400 mg of caffeine a day is not harmful for most people; energy drink labels may not give actual caffeine; limited data suggest energy drinks may temporarily improve alertness and endurance; lists who should check with a provider. source | |
| NHS (UK) (United Kingdom) | Says not more than 200 mg of caffeine a day in pregnancy; lists energy drink and some fitness supplement caffeine among sources. source | 2026-06-15 |
| NHS (UK) (United Kingdom) | Says 200 mg or more of vitamin B6 a day can cause peripheral neuropathy; high-dose nicotinic acid can cause flushes and long-term liver damage. source | 2020-08-03 |
| American Heart Association (United States) | 2026 scientific statement: data on high caffeine amounts such as in energy drinks are limited and generally suggest cardiovascular harm. source | 2026-09 |
When to get medical help
- Chest pain, fainting, a very fast or irregular heartbeat, or a seizure after using an energy or focus product: call emergency services.
- Vomiting, confusion, extreme restlessness or trouble breathing after a large amount of caffeine, or after swallowing a powder by mistake: call poison help (US 1-800-222-1222) or emergency services.
- Any child who has swallowed an energy product, powder or gummy meant for adults: call poison help right away.
- Numbness or tingling in the hands or feet that does not go away while taking B vitamins: stop the product and see a doctor.
Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
What are energy and focus blends?
They are products that mix caffeine with other ingredients such as B vitamins, taurine, sugar, guarana or L-theanine. They come as gummies, drinks, powders and shots, and are sold to improve energy, focus or alertness.
What is usually inside an energy drink or shot?
In a 2022 analysis of the 75 top-selling US energy drinks and shots, every product had caffeine (average 174.4 mg), most had B vitamins, and 37.3% had taurine. Products had about 18 listed ingredients on average.
Do these products improve focus?
For drinks and shots, an expert review says they can improve focus and alertness, mostly because of caffeine. No trial of a finished focus gummy or powder was found, so the evidence for those formats is insufficient.
Do the extra ingredients add anything beyond caffeine?
Do B vitamins in energy products give more energy?
B vitamins have a normal role in using energy from food, but a 2021 review of 16 trials found vitamin B12 did not improve thinking or mood in people who were not deficient, and tiredness could not be assessed.
What does 'proprietary blend' mean on a label?
It means the label may list the blend's ingredients without giving each one's amount. In the 2022 analysis, 15 of 75 products used proprietary blends with undisclosed amounts.
Are the caffeine amounts on labels accurate?
Can energy products affect the heart?
Are energy drinks and shots safe for teens and children?
Is it safe to use these in pregnancy?
What are the dangers of caffeine powder?
The FDA recommends avoiding pure or highly concentrated caffeine powders and says it knows of at least two deaths. One teaspoon of pure powder is about the caffeine in 28 cups of coffee.
Can I add up caffeine from several products?
You should. Caffeine can be in drinks, gum, bars, supplements and medicines, and the body handles added and natural caffeine alike. The FDA cites 400 mg a day for most adults and says it varies by person.
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Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our existing energy and focus formula summary, then re-read the FDA, MedlinePlus and NHS pages and the PubMed abstracts for every review, trial, statement and lab study cited. Only abstracts were read for studies. The NIH Office of Dietary Supplements pages were blocked and are marked unread.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown. Several expert statements cited come from authors with ties to sports supplement companies, and one tea review was partly funded by a tea company.
Sources 19
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
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- Desbrow B, Hall S, O'Connor H, Slater G, Barnes K, Grant G. Caffeine content of pre-workout supplements commonly used by Australian consumers.. Drug Test Anal. 2019. PMID 30196576. DOI 10.1002/dta.2501. (abstract)
- Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, Arent SM, Antonio J, Stout JR, Trexler ET, Smith-Ryan AE, Goldstein ER. International society of sports nutrition position stand: caffeine and exercise performance.. J Int Soc Sports Nutr. 2021. PMID 33388079. DOI 10.1186/s12970-020-00383-4. (abstract)
- Hack B, Penna EM, Talik T, Chandrashekhar R, Millard-Stafford M. Effect of Guarana (Paullinia cupana) on Cognitive Performance: A Systematic Review and Meta-Analysis.. Nutrients. 2023. PMID 36678305. DOI 10.3390/nu15020434. (abstract)
- Jagim AR, Harty PS, Barakat AR, Erickson JL, Carvalho V, Khurelbaatar C, Camic CL, Kerksick CM. Prevalence and Amounts of Common Ingredients Found in Energy Drinks and Shots.. Nutrients. 2022. PMID 35057494. DOI 10.3390/nu14020314. (abstract)
- Jagim AR, Harty PS, Tinsley GM, Kerksick CM, Gonzalez AM, Kreider RB, Arent SM, Jager R, Smith-Ryan AE, Stout JR, Campbell BI, VanDusseldorp T. International society of sports nutrition position stand: energy drinks and energy shots.. J Int Soc Sports Nutr. 2023. PMID 36862943. DOI 10.1080/15502783.2023.2171314. (abstract)
- Jeffries O, Hill J, Patterson SD, Waldron M. Energy Drink Doses of Caffeine and Taurine Have a Null or Negative Effect on Sprint Performance.. J Strength Cond Res. 2020. PMID 29065052. DOI 10.1519/JSC.0000000000002299. (abstract)
- Mandato J, Kola R, Tyson T, Laffin L, Bales R. The Effects of Energy Drinks on the Cardiovascular System: A Systematic Review.. Curr Cardiol Rep. 2025. PMID 41236610. DOI 10.1007/s11886-025-02293-w. (abstract)
- Marcus GM, Hu FB, van Dam RM, Cornelis MC, Dewland TA, Kang J, Larsson SC, Page RL 2nd, Parekh N, and the American Heart Association councils. Caffeine and Cardiovascular Disease: A Scientific Statement From the American Heart Association.. Circulation. 2026. PMID 42473796. DOI 10.1161/CIR.0000000000001454. (abstract)
- Markun S, Gravestock I, Jager L, Rosemann T, Pichierri G, Burgstaller JM. Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression.. Nutrients. 2021. PMID 33809274. DOI 10.3390/nu13030923. (abstract)
- Payne ER, Aceves-Martins M, Dubost J, Greyling A, de Roos B. Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Nutr Rev. 2025. PMID 40314930. DOI 10.1093/nutrit/nuaf054. (abstract)
- Thompson TR, Hays HL, Kistamgari S, Rine NI, Zhu M, Xiang H, Smith GA. Pediatric Exposures Associated with Caffeine Energy Products Reported to United States Poison Centers, 2011-2023.. J Med Toxicol. 2025. PMID 39890754. DOI 10.1007/s13181-025-01057-w. (abstract)
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- . FDA consumer update: Spilling the Beans: How Much Caffeine is Too Much?. . . (page)
- . FDA warns consumers about pure and highly concentrated caffeine. . . (page)
- . MedlinePlus: Caffeine. . . (page)
- . NHS: Foods to avoid in pregnancy (caffeine section). . . (page)
- . NHS: Vitamin B (B6 and niacin sections). . . (page)
