Urolithin A Side Effects & Safety: Is It Safe?

What have safety and tolerability studies found?

Urolithin A is a metabolite your gut microbiome can produce from ellagitannins found in foods like pomegranates, walnuts, and certain berries. Because many people's microbiomes convert it poorly, direct supplementation with a standardized form has been studied as a way to deliver a consistent amount. Every study below is a human trial.

• First-in-human trial, 2019. Published in Nature Metabolism, it tested single and repeated oral doses in healthy, sedentary older adults. Researchers reported that Urolithin A was safe, with no serious adverse events, and detectable in plasma (Andreux et al.).
• Middle-aged adults, 2022. A randomized, placebo-controlled trial in Cell Reports Medicine used 500 mg and 1,000 mg daily for four months and reported a favorable safety and tolerability profile (Singh et al.).
• Older adults, 2022. A four-month randomized trial in JAMA Network Open used 1,000 mg daily and concluded the ingredient was safe and well tolerated, with no statistically significant difference in adverse events versus placebo (Liu et al.).
• Immune aging, 2025. A 28-day randomized trial of 1,000 mg daily in 50 adults aged 45 to 70, published in Nature Aging (PubMed 41174221), continued to report good tolerability (Denk et al.).

A 2024 systematic review pooling five human studies (about 250 participants, up to 1,000 mg daily, 28 days to 4 months) found that adverse events were mild or moderate and unrelated to Urolithin A, with no serious Urolithin A-related side effects (Hodzic Kuerec et al., Ageing Research Reviews).

Studied doses and tolerability at a glance

These observations describe tolerability in study populations of generally healthy adults. They cannot predict how any one person will respond, and they do not cover people with serious illness, who were mostly excluded from trials. For how to choose between the two studied doses, see our Urolithin A dosage guide.

What is the regulatory status of Urolithin A?

In the United States, a GRAS notice for standardized, synthetic Urolithin A (identical to the compound your gut makes) was submitted to the Food and Drug Administration in 2018. The FDA completed its evaluation of that notice, GRN 791, and responded that it had no questions about the conclusion that Urolithin A is GRAS under its intended conditions of use. Those conditions describe use in foods for adults aged 40 and over, at up to 500 to 1,000 mg per serving and a maximum of 1 gram per day. You can read the GRAS notice and the FDA response letter directly.

Important context: a GRAS "no questions" letter relates to the safety of an ingredient for its intended use in food. It is not FDA approval, and it says nothing about effectiveness. As a dietary supplement, Urolithin A is intended to support normal structure and function of the body, not to diagnose, treat, cure, or prevent any condition. Our page on whether Urolithin A is FDA approved explains the difference in plain terms.

What side effects have people reported?

Across published controlled trials, reported side effects have been uncommon and mild, and rates in the Urolithin A groups have generally matched placebo. When effects are noted, they tend to be:

• Minor digestive discomfort, such as mild bloating, loose stools, or an upset stomach.
• Occasional, temporary symptoms that resolve on their own.

Practical tips if your stomach is sensitive:

• Take your dose with a meal, which is also how most trials gave it.
• Pick your largest meal of the day rather than a quick snack.
• Check the other ingredients, not just the Urolithin A. Many sugar-free gummies and bars are sweetened with sugar alcohols, which can loosen stools in some people at higher intakes.
• If a reaction concerns you or does not settle within a few days, stop and talk with your doctor.

Are there interactions, and who should be cautious?

Human data on drug interactions with Urolithin A are still limited. Trials have not systematically tested it alongside common medications, so the responsible approach is to treat interactions as unknown rather than assume there are none. Our page on Urolithin A drug interactions covers what is and is not known. The following groups should speak with a doctor or pharmacist before use:

• People who are pregnant or breastfeeding. Safety in these populations has not been studied, so it is best avoided unless your doctor advises otherwise. See Urolithin A while pregnant or breastfeeding.
• Children and teens. Studies have focused on adults, and the FDA-reviewed conditions of use refer to adults 40 and over. It is not intended for minors.
• Anyone taking prescription medications, including blood thinners, or living with a chronic health condition such as kidney or liver disease. A clinician who knows your history can advise.
• People preparing for surgery. Tell your care team about every supplement you take.

This is general educational information, not medical advice. For any personal health question, your doctor is the right resource. If you take standardized Urolithin A, a clearly dosed product such as SOMA Urolithin A gummies (1,000 mg per 4-gummy serving, within the 1 gram per day limit described in the GRAS notice) makes it easy to know exactly how much you are getting.

How do quality and purity affect safety?

With any supplement, the ingredient is only as trustworthy as the product delivering it. Dietary supplements are not checked by the FDA before they are sold, so the burden falls on the brand and on you. When comparing options, look for:

• A standardized, clearly labeled dose so you know how many milligrams of Urolithin A you are actually taking, and how many units make up a serving.
• Third-party or independent testing for identity, purity, and contaminants such as heavy metals.
• Manufacturing in a GMP-compliant facility and transparent sourcing.
• A realistic ingredient list without undisclosed proprietary blends.

You can see how SOMA approaches this on our quality and third-party testing page.

Frequently asked questions

Is Urolithin A safe to take every day?

In published trials, daily use for up to four months at 500 mg and 1,000 mg was reported as safe and well tolerated. Data beyond four months are limited, so it is reasonable to review ongoing use with your doctor at your regular checkups.

Does Urolithin A cause digestive side effects?

Most people tolerate it well. When digestive effects occur they are usually mild and temporary, such as minor bloating or stomach upset. Taking it with a meal may help.

Can I take Urolithin A with my medications?

Human interaction data are limited, so anyone on prescription medication should ask a doctor or pharmacist before combining it with a supplement, rather than assuming it is fine.

Is Urolithin A FDA approved?

Dietary supplements are not "FDA approved." The FDA responded with "no questions" to a GRAS safety notice for Urolithin A (GRN 791), which relates to ingredient safety in food, not approval or effectiveness.

Is there a maximum daily amount?

Human trials have not gone above 1,000 mg per day for extended periods, and the GRAS notice describes a maximum of 1 gram per day. There is no evidence that more adds benefit.

Who should not take Urolithin A?

People who are pregnant or breastfeeding and children should avoid it, and anyone with a medical condition or on medication should only use it if their doctor agrees.

SOMA Health

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