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Botanical illustration of Guava Leaf
MedicinalSourced entry

Guava Leaf

Psidium guajava

The leaves of the guava tree, widely used as a tea for diarrhea in the Caribbean, Latin America, Africa and Asia. Small trials have tested it for diarrhea, blood sugar after meals and gum inflammation.

Safety at a glance

Tap a box to read the safety notes below. “Nothing recorded” means our sources don't cover it, not that it's safe.

What is Guava Leaf?

Plant family
Myrtaceae, the myrtle family
Parts used
The leaves, often the young shoots and flower buds
Where it grows
Probably from the Brazilian Amazon; now grown in tropical and subtropical regions worldwide
Genus
Psidium
Species
guajava

Also called

Guava

Regional names

Guayaba, Goyave

Traditionally used for

  • Diarrhea
  • Vomiting
  • Skin rashes
  • Pimples
  • Diabetes
  • Ataque de nervios (traditional)

Traditionally described as

  • Leaf tea for diarrhea
  • Leaf wash for skin

Health topics

Where Guava Leaf appears in symptom search, and why. Being listed doesn't mean it's a proven treatment.

  • Diarrhea

    Traditional use in many countries. In one 5-day trial in 109 adults, people taking a guava leaf decoction recovered from sudden diarrhea faster than a comparison group given oral rehydration solution. Everyone knew which treatment they got.

  • High Blood Sugar

    Traditionally used for diabetes in East Asia. Small studies of a Japanese guava leaf tea found it lowered the rise in blood sugar after meals. The studies were reported by the tea's maker.

  • Occasional Nausea

    Traditional use only: in the Caribbean, a tea of the leaves or young shoots is used for vomiting. Not studied in people.

  • Skin Irritation, Rashes and Itching

    Traditional use only: in the Caribbean, a boiled leaf wash or bath is used for skin rashes and pimples. Not studied in people.

Traditions that use it

How it's prepared

Common ways Guava Leaf is prepared or sold. This isn't advice on how to take it; see Safety below.

  • Decoction

    TRAMIL's recipe for diarrhea or vomiting: 30 grams of fresh leaves (young shoots preferred) boiled for 5 minutes in 1 liter (4 cups) of water, optionally with a little salt and sugar; 1 cup 3 to 4 times a day.[1]Traditional text

  • Tea / Infusion

    In Japan, a guava leaf tea made from a water extract of the leaves is sold as a food for blood sugar after meals.[2]Study

Safety

Interactions with medicines

  • No interactions causing low blood sugar were seen when people took guava leaf tea with their diabetes medicines (insulin, sulfonylureas or biguanides such as metformin), with or without a statin for cholesterol. These were small studies reported by the tea's maker.[2]Study

Who should avoid it

Side effects

  • Healthy people who drank three times the usual amount of guava leaf tea (600 mL) had no diarrhea or low blood sugar. Trials of 8 to 12 weeks found no side effects.[2]Study

  • No side effects were reported in a 5-day trial of a guava leaf decoction in 109 adults with diarrhea.[3]Study

Pregnancy

Breastfeeding

Depends on how it's prepared

  • For diarrhea, use it alongside oral rehydration, not instead of it.

    Get medical help right away if someone with diarrhea shows signs of dehydration:

    • a dry tongue
    • skin that stays tented when pinched
    • passing little urine
    • crying without tears

    See a doctor if diarrhea lasts more than 3 days (1 day in children), if a skin problem lasts more than 5 days, or if the person gets worse. Don't keep a prepared tea for more than 24 hours, even in the fridge.[1]Traditional text

What does the research say?

Traditional use

These are traditional uses, not proven treatments.

  • TRAMIL, a Caribbean research program, records these traditional uses of the leaves, young shoots and flower buds:

    • Diarrhea: a tea, sometimes with salt or sugar.
    • Ataque de nervios (a "nervous attack"): a leaf tea.
    • Skin pimples and rashes: a boiled leaf wash or bath.
    • Dizziness from drunkenness, and vomiting: a tea of the leaves or shoots.

    TRAMIL recognizes all of these uses, based on how widely they're used and on safety studies.[1]Traditional text

  • A 2024 review found guava used for diarrhea in traditional medicine in 44 countries. The leaves were the part mentioned most often, usually boiled into a tea and drunk. Leaf and bark teas have been used for diarrhea and stomachache in the Americas, Africa and Asia.[4]Study

  • In East Asia and other countries, guava leaf extract has traditionally been used for diabetes.[2]Study

Laboratory & animal research

Lab and animal results show what might be worth studying in people. They don't show that the herb has these effects in humans.

  • In lab tests, a water extract of the leaves blocked gut enzymes that break down sugars. In diabetic mice, it improved blood sugar, insulin and blood fat levels.[2]Study

    Technical detail: alpha-glucosidase inhibition; improvements in hyperglycemia, hyperinsulinemia, hypoadiponectinemia, hypertriglyceridemia and hypercholesterolemia in murine models.

  • In lab and animal studies, about 27 compounds from guava have shown activity against diarrhea or bacteria.[4]Study

    Technical detail: benzophenone glycosides, terpenes, polysaccharides, phenols and flavonoids, including quercetin and its glycosides.

  • In mice, a single large dose of an alcohol-based leaf extract (2,000 mg per kg of body weight) caused no poisoning or deaths. Daily doses of up to 1,000 mg per kg for 28 days caused no harmful changes in blood tests or organs.[5]Study

    Technical detail: OECD 425 (acute) and OECD 407 (28-day sub-acute) guidelines; 250, 500 and 1000 mg/kg/day.

  • In mice and rats, powdered dried leaves didn't damage genes, and single doses of 2 g per kg of body weight caused no deaths or signs of poisoning.[1]Traditional text

    Technical detail: micronucleus test in mouse bone marrow; oral LD50 in mice above 2 g/kg; no histopathological changes in rats over 14 days.

Research in people

  • In a 5-day trial in India, 109 adults with sudden, uncomplicated diarrhea took a guava leaf decoction (made from 6, 10 or 14 leaves) three times a day, or were given oral rehydration solution as a comparison.

    The 14-leaf decoction (7.4 g of leaves) worked best: people were back to normal in about 72 hours, compared with 120 hours in the comparison group. Blood, liver and kidney tests stayed normal, and no side effects were reported. Everyone knew which treatment they got, which can bias results.[3]Study

    Technical detail: randomized, open-label, parallel-group, multi-arm; Sardar variety; outcomes were stool frequency and consistency; retrospectively registered (CTRI/2016/07/007095).

  • Studies of a Japanese guava leaf tea (Bansoureicha) in people:

    • In people with type 2 diabetes, one 200 mL serving with a meal lowered the rise in blood sugar after eating, though less than the diabetes medicine voglibose.
    • In 15 men with prediabetes or mild type 2 diabetes who drank it with every meal for 12 weeks, fasting blood sugar dipped slightly and insulin levels fell. Cholesterol and triglycerides fell in those whose levels started high.

    These studies were small. The review describing them was written by researchers at Yakult, which makes the tea, and one author holds patents on it.[2]Study

    Technical detail: fasting blood glucose 136 to 131 mg/dL (p = 0.07; the reduction rate was significant); insulin, C-peptide and HOMA-IR significantly decreased; approved in Japan as a Food for Specified Health Uses.

  • In a trial in India, 60 people with gum inflammation (gingivitis) had a professional teeth cleaning, then used a mouthwash for 30 days: 0.15% guava leaf, 0.2% chlorhexidine (a standard antiseptic mouthwash) or plain water.

    Gum inflammation, plaque and bacteria went down in all three groups. The guava and chlorhexidine groups improved more than the water group. The authors say longer studies are needed.[6]Study

    Technical detail: randomized, placebo-controlled; gingival index, plaque index and colony-forming units measured at baseline, 30 and 90 days; no significant difference in salivary antioxidant levels.

In short

TRAMIL advises against it in pregnancy, breastfeeding and children under 3; get medical help for diarrhea with signs of dehydration.

Sources

  1. [1] Psidium guajava — TRAMIL (Traditional Medicine in the Islands)Traditional text
  2. [2] Anti-hyperglycemic and anti-hyperlipidemic effects of guava leaf extract · DOI: 10.1186/1743-7075-7-9Peer-reviewed study
  3. [3] A randomized open label efficacy clinical trial of oral guava leaf decoction in patients with acute infectious diarrhoea · DOI: 10.1016/j.jaim.2020.04.001Peer-reviewed study
  4. [4] Ethnobotany, phytochemistry, and biological activities of Psidium guajava in the treatment of diarrhea: a review · DOI: 10.3389/fphar.2024.1459066Peer-reviewed study
  5. [5] Acute and sub-acute toxicological studies on the ethanol leaf extract of Psidium guajava in experimental mice · DOI: 10.11604/pamj.2026.53.49.49406Peer-reviewed study
  6. [6] Evaluation of a mouthrinse containing guava leaf extract as part of comprehensive oral care regimen: a randomized placebo-controlled clinical trial · DOI: 10.1186/s12906-019-2745-8Peer-reviewed study

This information is educational and traditional in nature, and is not a substitute for professional medical advice. Unfamiliar word? See what these words mean.