Ashwagandha safety: side effects, interactions and who should avoid it

What the safety data actually show

For healthy adults using it for a few weeks, ashwagandha looks reasonably well tolerated. A 2026 review of 23 trials and 2,317 people found standardized root extract at 125–600 mg/day was generally well tolerated. Mild gastrointestinal discomfort, headache and drowsiness were reported infrequently and about as often in placebo groups.

An earlier review pooled 30 human trials of root preparations and found no serious adverse events. That is a reassuring pattern, with two limits. Most trials ran from weeks to a couple of months, so long-term use is poorly characterized. And rare reactions rarely surface in trials of a few dozen people, which is why the case reports later in this article matter.

Common side effects, and what hasn't been measured

The effects reported most often are modest and mostly digestive or sedative:

• Drowsiness, which fits ashwagandha's sedative-type activity in lab research.
• Stomach discomfort or epigastric pain.
• Loose stools. Constipation is reported too, less often.
• Less commonly: nausea, reduced appetite, dry mouth, hyperacidity and skin rash.

In one small, uncontrolled tolerability study, 18 healthy adults escalated an 8:1 extract to 1,250 mg/day over 30 days. One volunteer was withdrawn for an adverse reaction. The reaction was reported as increased appetite and libido, plus vertigo with hallucinogenic effects, at the lowest dose tested. It is a single case, not a typical response, but it shows that unusual reactions exist.

Some commonly searched complaints have no trial data behind them. Emotional blunting, vivid dreams, irritability, heartburn and heavier periods were not measured as outcomes in the studies we reviewed. That means the question is open, not that the answer is no. If you notice a mood or body change after starting, treat it as worth mentioning to a clinician rather than waiting for it to pass.

If the problem is just an unsettled stomach, taking the dose with a meal is a reasonable adjustment. Persistent or severe symptoms deserve a call, particularly if they resemble the liver warning signs below.

Liver injury: rare, but documented

The most serious concern is the liver. A case report describes a 36-year-old man who took ashwagandha capsules at 1,350 mg/day for six months and developed liver injury judged probably caused by the supplement. A second case occurred in a person taking 450 mg for 45 days. Both resolved after the supplement was stopped.

A separate report describes a healthy 22-year-old who developed liver injury 30 hours after starting ashwagandha capsules; the dose wasn't reported. Other published cases exist internationally, and at least one is described as requiring a liver transplant.

Thyroid and hormonal effects

In a placebo-controlled trial of 50 adults with subclinical hypothyroidism, 600 mg/day of root extract for 8 weeks measurably shifted TSH, T3 and T4 compared with placebo. That is demonstrated hormonal activity, not a theoretical worry. If you have a thyroid condition or take thyroid medication, the combination could move your levels further than your prescribed dose intends.

The thyroid is not the only axis involved. A 2026 meta-analysis of 20 randomized trials found a small increase in testosterone. A trial in 57 overweight men raised DHEA-S and testosterone at a low dose. Two trials in women of perimenopausal age shifted estradiol, FSH and LH. These findings are often framed as benefits, but for anyone with a hormone-sensitive condition or on hormone therapy, they are also reasons to ask first.

Denmark's food regulator cited possible thyroid and reproductive or hormonal effects in 2020 when it said it could not establish a safe daily intake for ashwagandha root or extract. Danish authorities do not allow it to be sold there as a food supplement. Other regulators and sports bodies haven't reached the same conclusion, so treat it as one cautious national position, not a global verdict.

Drug and supplement interactions

No dedicated human trial has tested ashwagandha against a specific medication. Interaction advice therefore comes from three places: what ashwagandha does on its own, what is known about the drug class, and a few observational reports. That is an absence of evidence, not evidence of safety.

On antidepressants, a chart review linked ashwagandha plus four different antidepressants to side effects ranging from gastrointestinal symptoms to muscle and eye problems. The authors attributed these to additive effects and drug-metabolism interactions. Observational reports like this cannot prove causation, but they are a signal worth taking seriously if you take one.

On blood pressure, an 8-week trial of 80 healthy adults at 600 mg/day found no significant change in vital signs versus placebo. In adults with hypertension and anxiety, a 60-day trial at the same dose reported only a favorable trend. A 2018 review of herb-related heart-toxicity cases lists ashwagandha among about seven herbs, with problems ranging from irregular heart rate to arrhythmia, though the details aren't given in its abstract.

Stacking supplements adds another layer. Kava, for example, has its own liver signal: a case of liver injury at 10 g/day for five weeks, and more liver enzyme abnormalities than placebo in a 16-week anxiety trial. Nobody has studied it combined with ashwagandha. Two ingredients that each carry a liver question are better added one at a time, with a clinician aware. For a fuller list, see Electric Tiger's guide to ashwagandha and medications.

Who should avoid it or ask first

• Pregnant, nursing or trying to conceive. We found no trial establishing safety here, and product labels commonly advise against use. This is a conversation for your doctor, not something to solve with a lower dose.
• Under 18. One 8-week trial in 58 children and adolescents with mild ADHD at 300 mg/day reported no serious adverse events. That is a single small trial, and no general dosing guidance exists for minors. Ask a pediatric clinician.
• Thyroid conditions or thyroid medication. See the trial above.
• Liver disease, or a history of unexplained liver enzyme elevations.
• Autoimmune conditions or immunosuppressant therapy, including after a transplant.
• Anyone taking sedatives, antidepressants, or drugs for glucose, blood pressure or heart rhythm.
• Upcoming surgery. Sedative-type activity may interact with anesthesia, so tell your surgical team about any supplement beforehand.
• Known nightshade sensitivity. Ashwagandha belongs to the nightshade family, alongside tomato, potato and eggplant. This isn't an established allergen warning, but caution is sensible.

For a plain-language checklist, see who should not take ashwagandha.

Warning signs to stop and call a clinician

Stop taking it and seek medical advice if you notice any of the following:

• Yellowing of the skin or eyes, unusually dark urine, or persistent itching.
• Pain under the right ribs, new nausea, or unexplained fatigue.
• Hives, swelling or difficulty breathing.
• New palpitations or an irregular heartbeat.
• Stomach symptoms that are severe or persist beyond a few days.
• Marked daytime drowsiness, especially alongside other sedating medication.
• Any unexpected change in how you feel if you take thyroid medication, so levels can be checked.

The liver signs matter most because the reported cases resolved after stopping, which makes early recognition useful. The reaction in the 22-year-old came within 30 hours, so there is no safe window after which the risk is behind you.

Product quality, testing and regulation

Safety also depends on what is in the bottle. Lab testing of 24 commercial ashwagandha products found withanolide content off from the label by 2x to 35x. A label dose is therefore an estimate, and a cautious dose on paper can be a different one in practice. Third-party testing and standardized extracts reduce, but don't eliminate, that uncertainty.

A few regulatory facts are worth knowing. Ashwagandha isn't on the WADA Prohibited List, the NCAA banned-substances list or the Department of Defense's prohibited-ingredients list. Those programs still advise checking any specific product, because contamination is the real risk. No dietary supplement is FDA-approved before sale. India's 2026 advisory prohibits ashwagandha leaves and leaf extracts in food over withaferin-A concerns, while root and root extracts remain permitted.

For the wider evidence on benefits and uses, see our ashwagandha topic page.