As Urolithin A supplements gain popularity for mitochondrial health, one of the most common questions is: is Urolithin A safe to take? Here’s what clinical research and human trials have found.

What the Clinical Trials Show

Urolithin A has been tested in multiple human studies, including Phase 1 safety trials, and the evidence consistently points to a strong safety profile.

The first-in-human Phase 1 trial tested Urolithin A in single ascending doses ranging from 250 mg to 2,000 mg, as well as multiple ascending doses of 250, 500, and 1,000 mg per day for 28 days in 60 healthy elderly participants. The results were encouraging:

• No drug-related serious adverse events were reported
• No significant effects on laboratory parameters, biochemical tests, liver function, kidney function, or hematological markers
• Adverse events that did occur were generally mild, with no clear dose-dependent pattern

Subsequent trials — including studies on muscle health, immune function, and cardiovascular biomarkers — have reinforced these safety findings across different populations and dosing regimens.

Commonly Reported Side Effects

While most participants in clinical trials reported no side effects at all, a small number experienced mild, temporary symptoms:

Digestive Discomfort

The most frequently noted side effect. Some users report mild stomach discomfort or changes in digestion during the first few days of supplementation. This typically resolves on its own as the body adjusts. Taking Urolithin A with food can help minimize digestive sensitivity.

Headaches

A small number of study participants reported mild headaches, though these were not significantly more common in the Urolithin A group compared to placebo in controlled trials.

Muscle Aches

Occasionally reported, particularly in the initial days of supplementation. Since Urolithin A activates mitophagy (mitochondrial recycling), some researchers hypothesize that temporary muscle sensations could be related to the cellular renewal process.

What About Long-Term Safety?

Current clinical data extends to several months of continuous use, and no concerning long-term signals have been identified. However, it’s important to note that multi-year safety data is not yet available, as Urolithin A supplementation is a relatively recent development.

The compound received a favorable GRAS (Generally Recognized as Safe) review from the FDA in 2018, which involved standardized toxicological assessments confirming safety in both human and animal models.

A 2024 systematic review examining the evidence on Urolithin A in aging concluded that the compound shows a favorable safety profile across the available literature.

Who Should Be Cautious?

While Urolithin A is well-tolerated by most healthy adults, certain groups should consult a healthcare provider before starting supplementation:

• Pregnant or nursing women: No safety data available for this population
• People on immunosuppressant medications: Given Urolithin A’s effects on immune cell function, discuss potential interactions with your doctor
• Those with chronic kidney or liver conditions: While trials showed no impact on kidney or liver function in healthy adults, those with pre-existing conditions should seek medical advice
• Children and adolescents: Studies have been conducted in adults; safety in younger populations has not been established

Recommended Dosage and Safety

Based on published research, the clinically studied dosage range is 500 mg to 1,000 mg per day. Most studies used 500 mg for general health benefits and 1,000 mg for targeted outcomes like aerobic endurance and immune health.

Mitovia by Reviant Labs provides 500 mg per capsule of 99%+ pure Urolithin A, allowing you to take one capsule daily for standard dosing or two capsules for the higher clinical dose — matching the exact range used in published human trials.

The Bottom Line

Urolithin A is one of the most thoroughly safety-tested mitochondrial health compounds available. Clinical trials spanning multiple populations and dosing levels have consistently found it to be well-tolerated, with only mild and temporary side effects reported by a small number of users. As with any supplement, start at the standard dose and consult your healthcare provider if you have specific health concerns.

Read the science behind Urolithin A →