Guava leaf (Psidium guajava): Uses, Evidence and Safety
Guava leaf (Psidium guajava) as tea or extract: what small trials and reviews say about diarrhoea and blood sugar, and what is still unknown about safety and medicine interactions.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read herb safety and interactions before you use anything on this page.
What is Guava leaf 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.
Acute diarrhoea
Preliminary or mixedIn one open-label trial in 109 adults, a decoction of 14 guava leaves ended acute infectious diarrhoea in about 72 hours versus 120 hours with rehydration solution alone.
Supplements: Promising but small and open-label; not a replacement for rehydration, especially in children.
Abdominal pain with diarrhoea
Preliminary or mixedA trial of a standardised leaf product reduced abdominal pain episodes but not stool consistency or frequency, as reported by a 2024 review.
Supplements: Mixed result in one trial.
Blood sugar after meals
Preliminary or mixedSmall single-dose trials of guava leaf tea reported lower blood glucose after a rice meal; the effect was milder than the drug voglibose.
Supplements: Short-term effect in small trials; long-term benefit not shown.
Longer-term blood sugar and insulin measures
Not enough evidenceStudies of 8 to 12 weeks in 15 to 23 people gave mixed results; HbA1c fell only in some subgroups.
Supplements: Not established; do not replace prescribed diabetes care.
Cholesterol and triglycerides
Not enough evidenceFalls in cholesterol or triglycerides were reported only in small subgroups with high starting levels.
Supplements: Not established.
Antibacterial and anti-motility lab findings
Lab or animal research onlyLab and animal studies report antibacterial, anti-inflammatory and gut-motility effects of guava leaf extracts; many used very high concentrations.
Supplements: Lab and animal findings only.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (2)
- Blood Sugar BalancePreliminary or mixed
Small, short trials reported lower blood sugar after meals; longer-term results were mixed and no pooled analysis of guava leaf alone was found.
- Digestive SupportPreliminary or mixed
Guava leaf decoction ended acute diarrhoea sooner than rehydration alone in one open-label trial of 109 adults; only three clinical trials exist, so evidence is limited.
Body systems (2)
- Blood Sugar SupportPreliminary or mixed
Small, short trials reported lower blood sugar after meals; longer-term results were mixed and no pooled analysis of guava leaf alone was found.
- Digestive SystemPreliminary or mixed
Guava leaf decoction ended acute diarrhoea sooner than rehydration alone in one open-label trial of 109 adults; only three clinical trials exist, so evidence is limited.
Body parts (1)
- GutPreliminary or mixed
Studied for acute infectious diarrhoea; only a handful of small clinical trials.
Functional actions (2)
- Blood Sugar RegulationPreliminary or mixed
Small, short trials reported lower blood sugar after meals; longer-term results were mixed and no pooled analysis of guava leaf alone was found.
- Digestive SupportPreliminary or mixed
Guava leaf decoction ended acute diarrhoea sooner than rehydration alone in one open-label trial of 109 adults; only three clinical trials exist, so evidence is limited.
Root causes (2)
- Digestive DysfunctionPreliminary or mixed
Used for acute infectious diarrhoea; the evidence is small and open-label.
- Medication Side EffectsDocumented risk
Trial authors say interactions with diabetes and other common medicines are not well studied; people on glucose-lowering medicines should monitor blood sugar and ask their clinician.
Biomarkers (2)
- Blood GlucosePreliminary or mixed
Single-dose tea trials reported lower glucose after a rice meal; a 2026 meta-analysis of related Myrtaceae plants found a small fasting-glucose fall (low certainty) but did not mention guava.
- HbA1cPreliminary or mixed
HbA1c fell only in some subgroups of small 8 to 12 week studies; a 2026 meta-analysis of related plants found no clear HbA1c change.
Documented risks and interactions (2)
- Blood-sugar medicines and low blood sugar. Trials reported no low blood sugar in people taking diabetes medicines, but the authors say interactions with common medicines are not well studied.
- Safety data are limited, especially in children. A 2024 review says safety in children and the right amount to use are unknown; lab toxicity results were mixed by model and extraction method.
Safety first: blood-sugar medicines, children, pregnancy and long-term use
Guava leaf products are not the same as eating guava fruit, and the safety data are thin. The reviews we read call for more clinical trials and more safety data, and one says safety in children and the right amount to use are still unknown. [1][2] The small human trials reported no serious side effects, but they were short (days to about 12 weeks) and involved few people. [3][4] If you take medicines for diabetes, tell your prescriber or pharmacist before drinking guava leaf tea regularly: the leaf extract is studied for lowering blood sugar after meals, and the trial authors themselves say interactions with common medicines are not well studied. [3] Do not use leaf tea to replace diabetes treatment or oral rehydration for a child with diarrhoea. Pregnancy and breastfeeding: Proper evidence not found in the sources we read. See how herb and medicine interactions work, diabetes and supplements and supplements before surgery.Overview
Guava leaf is the leaf of Psidium guajava L., a tree in the myrtle family (Myrtaceae); GBIF lists this as the accepted name. [5] This page covers the leaf, used as a tea, a decoction (leaves simmered in water) or a concentrated extract. The fruit is a food and is covered separately on the guava fruit page. Native range: not found in the sources we read. Many studies describe preparations that differ in leaf number, extraction method and strength, so results for one product do not automatically apply to another. [2]Traditional use (not proof of benefit)
A 2024 review found guava used traditionally for diarrhoea in 44 countries, with the leaf the most-cited plant part (about 64% of citations) and decoction the most common preparation. [2] That shows how widespread the use is, not that it works. Guava leaf is also used as a tea in diabetes care in some places; the research on that is covered below.What research shows
| Use | What the sources found | Strength of evidence | Form and population |
|---|---|---|---|
| Acute infectious diarrhoea | An open-label randomised trial in 109 adults compared leaf decoctions (6, 10 or 14 leaves) with oral rehydration solution; the 14-leaf group returned to normal in 72 hours versus 120 hours for controls, with no adverse events reported. [1][6] A 2024 systematic review of 23 studies found only three clinical trials; most were laboratory or animal studies. [7] | Promising but limited | Leaf decoction; adults |
| Abdominal pain with diarrhoea | A second trial of a standardised leaf product (100 patients) reduced abdominal pain episodes but not stool consistency or frequency, as reported by the 2024 review (we did not read the trial itself). [2] | Mixed | Standardised leaf product; adults |
| Blood sugar after meals | In a company-authored review, single-dose tea trials (19 and 20 people) lowered glucose after a meal; the tea's effect was milder than the diabetes drug voglibose. [3] | Promising but limited | Leaf tea or extract; adults, short term |
| Longer-term blood sugar (HbA1c) | The same review describes 8 to 12 week studies of 15 to 23 people with mixed results: in a 12-week study of 15 men, fasting glucose and HbA1c did not change significantly (insulin measures fell), and in an 8-week study HbA1c fell only in people starting above 6.5%. [3] | Insufficient evidence | Leaf tea; people with prediabetes or mild type 2 diabetes |
| Cholesterol and triglycerides | Falls were reported only in small subgroups with high starting levels. [3] | Insufficient evidence | Leaf tea; adults |
| Pooled trials of related plants | A 2026 meta-analysis of 13 trials (802 people) of jamun and other Myrtaceae plants found a small fall in fasting glucose but no clear change in HbA1c or after-meal glucose; certainty was low to very low. Its abstract did not mention guava, so it cannot be read as a guava result. [8] | Insufficient evidence for guava specifically | Various Myrtaceae products |
We did not find a meta-analysis that pools randomised trials of guava leaf alone. A common explanation for the blood-sugar effect is that leaf compounds slow carbohydrate-digesting enzymes in lab tests, which is a mechanism proposed in the lab, not proof of benefit in people. [3] Leaf tea for menstrual cramps, weight loss, cancer or skin: Proper evidence not found in the sources we read.
Forms and why the form matters
Studies used a home-style decoction of fresh or dried leaves for diarrhoea, a standardised leaf product in one trial, and a commercial leaf tea or extract for blood sugar. [2][3][6] The 2024 review noted that many studies omitted extract strength and dosing details. [2] Capsules and extracts sold online vary, and the site cannot say which, if any, match what was studied. How much to use is a decision for a clinician or pharmacist, not this page.Safety in more detail
- Side effects: the small trials reported no adverse events, and the diarrhoea trial reported blood, liver and kidney measures within normal ranges. [3][6] Absence of reports in short, small trials is not proof of safety.
- Animal and lab safety: the 2024 review found mixed results: leaf extract had low acute toxicity in rats, but a leaf decoction was toxic to human lung cells in a lab test, and the authors say safety varies by model, extraction method and plant part. [2]
- Diabetes medicines: the trials reported no low blood sugar or drug problems in people already taking diabetes medicines, but they were small, and the authors ask for more study of interactions. [3] People on insulin or glucose-lowering tablets should monitor blood sugar and ask their clinician. We could not read a pharmacology reference to confirm or rule out an interaction.
- Pregnancy and breastfeeding: Proper evidence not found in the sources we read. See pregnancy and breastfeeding safety.
- Children: safety and appropriate amounts for children are unknown according to the 2024 review. [2] Diarrhoea in young children needs medical advice; see oral rehydration solutions.
- Liver and kidney: the only data we read were blood-test results in one trial; we could not read NIH LiverTox for guava leaf, so we make no claim either way. [6]
- Surgery: no guidance found in the sources we read; because the leaf is studied for blood sugar, tell the surgical team.
- Allergy and quality: Proper evidence not found in the sources we read. Products vary in strength and purity; see quality testing and certifications.
Official statements
- EMA, WHO, NCCIH, Memorial Sloan Kettering: we did not find a guava leaf monograph or fact sheet at these bodies in the pages we tried (the Memorial Sloan Kettering page returned not found). Legal status: not found in the sources we read.
Related pages
Frequently asked questions
Does guava leaf tea help diarrhoea?
One open-label trial in 109 adults found leaf decoction ended acute diarrhoea sooner than rehydration solution alone, but a 2024 review found only three clinical trials in total. [6][7] Treat it as promising, not proven.
Does guava leaf lower blood sugar?
Small short trials reported lower blood sugar after a meal, mostly from a company-authored review. [3] We found no pooled analysis of guava leaf alone, and longer-term results were mixed. [3][8]
Can I drink guava leaf tea with diabetes medicines?
The small trials reported no low blood sugar, but interactions are not well studied. [3] Ask a pharmacist or doctor and check your blood sugar as advised.
Is guava leaf the same as guava fruit?
No. The studies on the leaf used leaf decoctions, teas or extracts, and fruit results do not carry over. See the guava fruit page.
Is guava leaf safe in pregnancy or for children?
Proper evidence not found in the sources we read for pregnancy; for children, a 2024 review says safety is unknown. [2]
References
- Birdi T et al. A randomized open label efficacy clinical trial of oral guava leaf decoction in patients with acute infectious diarrhoea. Journal of Ayurveda and Integrative Medicine, 2020. PMID 32507357. Abstract read via Europe PMC 2026-10-23.
- Liu et al. Psidium guajava for diarrhoea: ethnobotany, pharmacology and safety review. Frontiers in Pharmacology, 2024. PMID 39246650. Read 2026-10-23 (first part of the text only).
- Deguchi Y, Miyazaki K. Anti-hyperglycemic and anti-hyperlipidemic effects of guava leaf extract. Nutrition & Metabolism, 2010. PMID 20181067. Authors work for Yakult, which holds patents on guava leaf tea. Read 2026-10-23.
- Kaur S, Chaudhary R. A comprehensive review of the effects of Psidium guajava and Syzygium cumini leaves on diabetes mellitus. Preventive Nutrition and Food Science, 2025. PMID 40612758. Abstract read via Europe PMC 2026-10-23 (it describes no human trials).
- GBIF Secretariat. GBIF Backbone Taxonomy species match. Accepted name Psidium guajava L., family Myrtaceae. Read 2026-10-23.
- Birdi T et al., as source 1 (adverse events and blood, liver and kidney measures).
- Garrido G et al. Antidiarrheal effect of Psidium guajava L. extract in acute diarrhea: a systematic review. Journal of the Science of Food and Agriculture, 2024. PMID 38578668. Abstract read via Europe PMC 2026-10-23.
- Efficacy and Safety of Syzygium cumini and Related Myrtaceae Interventions for Dysglycemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Foods, 2026. PMID 42450449. Abstract read via Europe PMC 2026-10-23.