Holy Basil (Tulsi)
What holy basil or tulsi (Ocimum tenuiflorum) is, how it differs from sweet basil, what small trials found for stress and blood sugar, and the safety gaps that remain.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
What is Holy basil (tulsi) good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Perceived stress and stress symptoms
Preliminary or mixedIn two placebo-controlled trials in adults with stress, holy basil extract was linked to lower stress scores. The trials were small and short, and used specific branded extracts.
Supplements: Two placebo-controlled trials (6 and 8 weeks) reported lower stress scores; the wider evidence base is small and results may not carry over to teas or other products.
Sleep quality in people under stress
Preliminary or mixedOne 8-week trial found better insomnia-scale scores than placebo in stressed adults. It is a single trial.
Supplements: One trial of one extract; not established for people with clinical insomnia.
Cortisol response to stress
Preliminary or mixedIn one trial, hair and saliva cortisol were lower than with placebo after 8 weeks and after a laboratory stress test. Cortisol is a lab marker, not how a person feels.
Supplements: A lower marker in one trial does not prove a health benefit.
Blood glucose in type 2 diabetes
Preliminary or mixedIn a small single-blind crossover trial, holy basil leaves lowered fasting and after-meal blood glucose compared with placebo leaves in adults with type 2 diabetes.
Supplements: Small, single-blind and old (1996); a systematic review calls the wider evidence limited. Not a replacement for diabetes care.
Cholesterol
Not enough evidenceThe same diabetes trial saw a mild fall in total cholesterol. This is too little to say holy basil helps cholesterol.
Supplements: Insufficient evidence.
Thinking, immunity and heart-related outcomes
Not enough evidenceA systematic review lists human studies on neurocognition, immunity and cardiovascular outcomes. Most are small, from India, and of limited quality.
Supplements: Insufficient evidence from the sources read.
Traditional use in Ayurveda and Siddha
Not enough evidenceTulsi is highly regarded in Ayurvedic and Siddha medicine. Traditional use is not evidence that it works.
Supplements: Tradition does not show benefit.
Laboratory and animal findings
Lab or animal research onlyLab and animal studies attribute many actions to tulsi, including adaptogenic, antimicrobial, anti-inflammatory and immune effects. These do not show effects in people.
Supplements: Lab and animal research only.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (3)
- Stress ReductionPreliminary or mixed
Two placebo-controlled trials in stressed adults reported lower stress scores. The trials were small and used specific extracts.
- Blood Sugar BalancePreliminary or mixed
A small single-blind trial in type 2 diabetes reported lower glucose. Evidence is limited; ask a clinician if you use diabetes medicines.
- Sleep QualityPreliminary or mixed
One 8-week trial found better insomnia-scale scores than placebo in stressed adults.
Body systems (3)
- Stress & MoodPreliminary or mixed
Used for stress; small trials reported lower stress scores.
- Blood Sugar SupportPreliminary or mixed
A small trial reported lower blood glucose in type 2 diabetes.
- Sleep & RecoveryPreliminary or mixed
One trial reported better insomnia scores in stressed adults.
Functional actions (2)
- Stress ReductionPreliminary or mixed
Two placebo-controlled trials reported lower stress scores.
- Blood Sugar RegulationPreliminary or mixed
A small trial reported lower glucose; evidence is limited.
Root causes (2)
- Chronic StressPreliminary or mixed
Trials in stressed adults reported lower stress scores; it does not remove the cause of stress.
- Blood Sugar ImbalancePreliminary or mixed
One small trial reported lower glucose in type 2 diabetes.
Biomarkers (2)
- Blood GlucosePreliminary or mixed
Fasting and after-meal glucose were lower in one small trial in type 2 diabetes.
- CortisolPreliminary or mixed
In one trial hair and saliva cortisol were lower than with placebo. A lab marker is not the same as feeling better.
Conditions & symptoms (1)
- Diabetes MellitusPreliminary or mixed
A small single-blind trial in type 2 diabetes reported lower glucose. Evidence is limited and it does not replace diabetes care.
Documented risks and interactions (1)
- Product variation and name confusion. Holy basil (Ocimum tenuiflorum) is not the kitchen basil (Ocimum basilicum). Species, leaf type, extract and quality differ between products, and many studies did not report them.
What it is
Holy basil, called tulsi in India, is Ocimum tenuiflorum L., in the mint family (Lamiaceae). The older name Ocimum sanctum L. is treated as a synonym. [2] Trials we read used dried holy basil leaves [3] or extracts. [4][5]Name traps. It is not sweet basil (Ocimum basilicum), the kitchen herb; see basil. A review notes two tulsi types within O. tenuiflorum (Rama and Krishna, with different leaf color) and a third plant, Ocimum gratissimum (Vana tulsi), and that only two of the reviewed trials said which type they used. [6]
Is it an "adaptogen"?
"Adaptogen" is a contested term. A systematic review lists adaptogenic effects among the many actions attributed to tulsi in laboratory, animal and human studies. [1] The sources we read do not show an agreed classification. See what adaptogens are.Traditional use (not proof)
The same review describes tulsi as highly revered for medicinal uses in the Ayurvedic and Siddha systems and indigenous to the Indian continent. [1] See tulsi in Ayurveda and tulsi tea. Tradition is not evidence that a supplement works.What research shows
| Use | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Overall human evidence | A systematic review found 24 human studies, all reporting favorable outcomes and no significant adverse events; most were in India and published in local journals, and the authors cannot be sure they found them all. [1][6] | Promising but limited | Mixed populations; leaf, extracts |
| Stress and sleep | In 100 adults aged 18 to 65, a standardized extract (125 mg twice daily) for 8 weeks improved Perceived Stress Scale and insomnia scores versus placebo, with lower hair cortisol and lower saliva cortisol after a lab stress test. [4] In 150 adults, an extract for 6 weeks lowered stress symptom scores versus placebo. [5] | Promising but limited | Adults with stress; extracts |
| Blood glucose | In a single-blind crossover trial of people with non-insulin-dependent diabetes, holy basil leaves lowered fasting glucose by 21.0 mg/dl versus placebo leaves. [3] | Preliminary (small, single-blind) | Adults with type 2 diabetes; leaves |
| Thyroid, menopause, other uses | Proper evidence not found in the sources read for this page. | Insufficient evidence | Not applicable |
Cortisol is a biomarker, not how a person feels. See adrenal fatigue claims. Results from a leaf extract do not transfer to tea, powder or capsules of a different product.
Forms matter
Trials used dried leaves and extracts; tea made at home is a different product with its own amounts. See adaptogen teas and infusions and standardized extracts.Where to go next
Holy basil for stress, blood sugar and thyroid and ashwagandha versus holy basil.Frequently asked questions
Is holy basil the same as basil?
No. Tulsi is Ocimum tenuiflorum; kitchen basil is Ocimum basilicum. [2]
Does holy basil reduce stress?
Two small placebo-controlled trials reported lower stress scores, but the evidence base is small. [4][5]
Is it safe in pregnancy?
Proper evidence not found in the sources we read. Ask a clinician.
Can it lower blood sugar?
One single-blind crossover trial reported lower fasting and after-meal glucose with holy basil leaves. [3]
How long has it been studied?
The longest study in a systematic review lasted 13 weeks. [6]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety points first
- Blood sugar. Two trials we read reported lower blood glucose with holy basil (below). People who use diabetes medicines should ask a pharmacist or clinician before adding it. We did not find a source that documents a drug interaction.
- Pregnancy, breastfeeding, children, liver, kidney, surgery, medicines. Proper evidence not found. We searched NIH NCCIH and Memorial Sloan Kettering (no holy basil page found), PubMed and Europe PMC, and found no specific statement for these groups. Lack of evidence is not proof of safety; see pregnancy and breastfeeding and how interactions work.
- Long-term use. A systematic review found only one trial that reported an adverse effect (transient mild nausea), but the longest study lasted 13 weeks, so long-term effects are not known. [1]
- Products. Quality and contamination vary; see quality testing and certifications.
References
- Jamshidi et al. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. Evidence-based complementary and alternative medicine : eCAM 2017. PubMed 28400848. Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy. Names checked through the species match API on 2026-10-23. Read 2026-10-23.
- Agrawal et al. Randomized placebo-controlled, single blind trial of holy basil leaves in patients with noninsulin-dependent diabetes mellitus. International journal of clinical pharmacology and therapeutics 1996. PubMed 8880292. Read 2026-10-23.
- Lopresti et al. A randomized, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (Holy Basil) extract on stress, mood, and sleep in adults experiencing stress. Frontiers in nutrition 2022. PubMed 36185698. Read 2026-10-23.
- Saxena et al. Efficacy of an Extract of Ocimum tenuiflorum in the Management of General Stress: A Double-Blind, Placebo-Controlled Study. Evidence-based complementary and alternative medicine : eCAM 2012. PubMed 21977056. Read 2026-10-23.
- Jamshidi et al. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature (full text). Evid Based Complement Alternat Med 2017. Europe PMC PMC5376420. Read 2026-10-23.