What are kombucha side effects?
Mayo Clinic reports that kombucha has caused stomach upset, infections and allergic reactions in some people. Home brews made in unclean conditions can grow harmful bacteria. Brewing in lead-glazed ceramic can leach lead into the drink. Some kombucha also contains alcohol, which can increase if it keeps fermenting in the bottle.
Updated
Key facts
- Reported harms. Stomach upset, infections, allergic reactions. [1]
- Home hygiene. Unclean home brewing makes harmful bacterial growth likely. [1]
- Lead risk. Acids can leach lead from ceramic glazes. [1]
- Alcohol. Fermentation can continue in the bottle and raise alcohol to 0.5% or more. [2]
What side effects are reported?
Mayo Clinic says kombucha has caused stomach upset, infections and allergic reactions in some people, and that home brewing under unclean conditions makes it likely that bad bacteria can grow. Lead poisoning has happened when kombucha was made in lead-containing ceramic pots, because the acids pull lead from the glaze. [1]
Can kombucha contain alcohol?
Yes. TTB says sugar and yeast can produce kombucha at 0.5% alcohol or more, and fermentation may continue in the bottle after it leaves the producer. [2] A 2022 study measured 0% to 1.29% ethanol across nine commercial products. [3] More: does kombucha have alcohol.
Who should be careful?
Mayo Clinic advises people who are pregnant or breastfeeding, or who have weakened immune systems, to avoid kombucha, and others to drink it only from a trusted source. [1]
Related answers: kombucha health benefits · does kombucha have alcohol
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We don't give health advice. For questions about your health, talk to a doctor or pharmacist.
Questions
Can drinking too much kombucha be harmful?
Mayo Clinic does not set a safe amount, but reports harms including stomach upset, infections and allergic reactions. Ask a clinician if you have health conditions. [1]
Does kombucha contain caffeine?
Usually some, from the tea. A 2022 analysis found caffeine in all nine commercial products tested, at very different levels. [3]
Sources
- Kombucha tea: Does it have health benefits? — Mayo Clinic
- Kombucha Information and Resources — Alcohol and Tobacco Tax and Trade Bureau (TTB)
- Microbial and Chemical Profiles of Commercial Kombucha Products (Nutrients, 2022) — Yang J. et al. — PubMed Central