Short answer
Guava leaf (Psidium guajava) is a common folk tea in tropical regions, traditionally used for diarrhea and, in East Asia, to blunt after-meal blood sugar spikes. Research includes a 50-patient trial in acute diarrhea that found a shorter duration of abdominal pain, a 12-week pilot in people with knee pain that found less pain than placebo, and lab and animal data showing it slows sugar absorption. Larger human trials are lacking. [1] [2] [3]
Key takeaways
- Guava leaf is used in 44 countries in traditional medicine, mostly as a decoction, especially for diarrhea. [4]
- In Japan a guava leaf tea is approved as a Food for Specified Health Uses, aimed at after-meal blood sugar; the supporting data are mixed lab, animal and small human studies. [5]
- In a trial of 50 adults with acute diarrhea, 500 mg quercetin-standardized capsules three times a day for 3 days shortened abdominal pain. [1]
- Lab and animal studies show extracts slow glucose transport; it is not a substitute for diabetes treatment. [3]
- Lab and rat data suggest guava leaf tea is unlikely to interact with drugs including warfarin, but ask your pharmacist. [6]
Guava leaves are among the most widely used folk teas in the tropics, and one of the few where a commercial tea has regulatory recognition for a stated purpose. They are one of the four ingredients in Bowel Balance and one of the four in Sacred Sacral.
Here is what the research actually supports.
What is guava leaf?
Guava is Psidium guajava, a small tropical tree of the myrtle family, grown for its fruit and for its leaves. A review of its pharmacology lists flavonoids, alkaloids, tannins, triterpenoids and essential oils among its constituents. [7] Leaves are the most commonly cited plant part in traditional use.
Traditional uses of guava leaf tea
A 2024 review of 189 studies found guava is used in traditional medicine in 44 countries, most often as a leaf decoction taken by mouth, especially for diarrhea. It also isolated about 27 compounds with antidiarrheal or antibacterial activity. The authors noted open questions about mechanism and safety in children. [4] In East Asia the leaf tea is also taken for blood sugar after meals. [5]
What research shows
Stomach upset and diarrhea
In a randomized, double-blind trial, 50 adults with acute diarrheal disease took 500 mg capsules of a quercetin-standardized guava leaf product every 8 hours for 3 days. The product decreased the duration of abdominal pain. [1] That is a standardized capsule, not a tea, and it is a small study.
After-meal blood sugar
In Japan, a guava leaf tea made from an aqueous extract has been approved as a Food for Specified Health Uses. A review describes how the extract inhibits alpha-glucosidase enzymes in vitro, reduces after-meal glucose in animals and has been tested in several clinical trials, and proposes that long-term suppression of after-meal spikes could help prevent type 2 diabetes. [5] In a 2018 study, guava leaf and fruit extracts inhibited glucose transport in intestinal cells by up to 80% and lowered blood glucose about fourfold in mice. [3] The evidence is mostly lab and animal; people with diabetes should never replace medication with tea, and should tell their care team they drink it.
Knee pain (small pilot)
In a 12-week randomized, double-blind pilot study in Japanese adults with knee pain, 1 g a day of guava leaf extract produced lower knee pain and stiffness scores than placebo at week 12. The authors concluded that continued intake might relieve knee pain, and called it pilot data. [2]
| Use | Evidence level | What we know |
|---|---|---|
| Diarrhea | Small RCT (capsule), reviews of traditional use | Shorter abdominal pain in 50 patients. [1] [4] |
| After-meal blood sugar | Lab, animal, small human studies; approved Japanese food claim | Slows glucose transport and enzyme activity. [5] [3] |
| Knee pain | One pilot RCT, extract | Less pain vs placebo at 12 weeks. [2] |
| Treating diabetes | No evidence as a treatment | Not a replacement for medication. |
Guava leaf tea side effects and drug interactions
A study of guava leaf tea's potential to interact with drugs found that polyphenols from the leaf showed some inhibition of human cytochrome P450 enzymes, but weaker than grapefruit juice. In rats, 90 days of guava leaf extract did not change liver weight or CYP3A expression, and guava leaf tea did not alter the clotting effect of warfarin. The authors concluded the tea is unlikely to interact with drugs. [6] That is a lab and rat result, so people on warfarin, diabetes drugs or other narrow-margin medicines should still ask their pharmacist.
- Diabetes medication: guava leaf may add to blood sugar lowering, so monitor and tell your care team.
- Pregnancy and breastfeeding: not enough safety data on medicinal amounts; ask a clinician.
- Children: a review flagged unanswered questions about safety in children. [4]
How to make guava leaf tea
Steep 1 to 2 teaspoons of dried guava leaf in a cup of just-boiled water, covered, for 10 to 15 minutes. In our blends, guava leaf is combined with other herbs. Bowel Balance (fennel, guava leaf, tipo, stevia leaf) and Sacred Sacral (fig leaf, guava leaf, guaviduca, stevia) are each prepared by bringing 2 cups of water to a gentle boil, adding 1 heaping tablespoon, turning off the heat, covering and steeping for 15 minutes, then straining and drinking warm. Our infusion vs decoction guide has more on method.
Frequently asked questions
What are the benefits of guava leaf tea?
Does guava leaf tea lower blood sugar?
Does guava leaf tea have side effects?
Generally mild. It may add to blood sugar medication and may be mildly constipating. Rat and lab data suggest low drug interaction risk, but ask your pharmacist if you take warfarin or diabetes medicine. [6]
Is guava leaf good for diarrhea?
How do you make guava leaf tea?
Steep 1 to 2 teaspoons of dried leaf in a cup of just-boiled water, covered, for 10 to 15 minutes.
Where can I buy guava leaf tea blends?
Kawsaypac's Bowel Balance and Sacred Sacral blends contain guava leaf and ship across the USA: Bowel Balance, Sacred Sacral.
References
- Lozoya X, Reyes-Morales H, Chávez-Soto MA, et al. (2002). Intestinal anti-spasmodic effect of a phytodrug of Psidium guajava folia in the treatment of acute diarrheic disease. J Ethnopharmacol. PubMed 12413703 · DOI
- Kakuo S, Fushimi T, Kawasaki K, et al. (2018). Effects of Psidium guajava Linn. leaf extract in Japanese subjects with knee pain: a randomized, double-blind, placebo-controlled, parallel pilot study. Aging Clin Exp Res. PubMed 29687303 · DOI
- Müller U, Stübl F, Schwarzinger B, et al. (2018). In Vitro and In Vivo Inhibition of Intestinal Glucose Transport by Guava (Psidium Guajava) Extracts. Mol Nutr Food Res. PubMed 29688623 · DOI
- Liu C, Jullian V, Chassagne F (2024). Ethnobotany, phytochemistry, and biological activities of Psidium guajava in the treatment of diarrhea: a review. Front Pharmacol. PubMed 39246650 · DOI
- Deguchi Y, Miyazaki K (2010). Anti-hyperglycemic and anti-hyperlipidemic effects of guava leaf extract. Nutr Metab (Lond). PubMed 20181067 · DOI
- Kaneko K, Suzuki K, Iwadate-Iwata E, et al. (2013). Evaluation of food-drug interaction of guava leaf tea. Phytother Res. PubMed 22566187 · DOI
- Chechani B, Roat P, Hada S, et al. (2024). Psidium guajava: An Insight into Ethnomedicinal Uses, Phytochemistry, and Pharmacology. Comb Chem High Throughput Screen. PubMed 37170987 · DOI