Ashwagandha Side Effects, Interactions and Who Should Skip It

Ashwagandha side effects: the full safety picture

Ashwagandha side effects in trials are usually mild — sleepiness, stomach discomfort and loose stools are the ones reported most often — but there are less-discussed safety signals that deserve more attention than the average product page gives them: rare cases of liver injury, effects on thyroid hormones, a list of medicine interactions, and clear advice to avoid it in pregnancy and breastfeeding. NCCIH also notes that it may be safe in the short term (up to three months) and that there is not enough information to judge long-term safety. This article sets out that picture so you can make an informed decision rather than relying on marketing copy.

None of this is medical advice. If you have a health condition or take prescription medicine, the right next step is a conversation with a clinician or pharmacist, not a supplement forum.

Common, mild side effects

A 2020 review of 30 human trials of ashwagandha root preparations found no serious adverse events and no changes in blood tests or vital signs; the most common side effects (reported in more than 5% of people) were mild and mostly short-lived — sleepiness, discomfort in the upper stomach and loose stools (Tandon and Yadav, 2020). NCCIH lists drowsiness, stomach upset, diarrhoea and vomiting. Taking it with food, or lowering the dose, is a reasonable first step if you get stomach symptoms. This is the least concerning part of the safety profile.

Liver injury: what the case reports show

NCCIH describes liver injury linked to ashwagandha supplements as rare, but there have been a number of cases. A case series from Iceland and the US described five people who developed jaundice with nausea, lethargy, itching and abdominal discomfort 2 to 12 weeks after starting ashwagandha; the injury was cholestatic or mixed, the itching and jaundice lasted 5 to 20 weeks, and none developed liver failure (Björnsson et al., 2020). A later series from India reported 23 patients with ashwagandha-related liver injury, again mostly cholestatic hepatitis (Philips et al., 2023). A 2026 review of drug-induced liver injury lists ashwagandha among the herbal supplements newly recognised as causing it (Björnsson, 2026).

"Rare" is not "never", and this is exactly the kind of signal that gets dropped from enthusiastic marketing pages. Anyone with existing liver disease should speak to a doctor before using it, and anyone who develops jaundice (yellowing of the skin or eyes), dark urine, itching, unusual tiredness, nausea or abdominal pain while taking ashwagandha should stop and seek medical attention.

Thyroid effects

Ashwagandha can raise thyroid hormone levels. In a placebo-controlled trial in people with subclinical hypothyroidism, 600 mg of root extract a day for eight weeks shifted TSH, T3 and T4 towards the normal range (Sharma et al., 2018). In another trial, where thyroid tests were only a safety check, the three ashwagandha-treated patients with abnormal readings all saw T4 rise (Gannon et al., 2014). There are also case reports of thyrotoxicosis — an overactive-thyroid state — in people taking ashwagandha, which settled after they stopped.

NCCIH says ashwagandha is not recommended for people with thyroid disorders and may interact with thyroid hormone medicines. That makes it a real reason to speak to your doctor first if you have an overactive or underactive thyroid or take thyroid medication, rather than self-experimenting.

Emotional blunting and mood effects

Some users describe feeling emotionally "flat" on ashwagandha. We did not find a controlled trial that measured this, so treat it as an unconfirmed report rather than an established effect. What is established is narrower: NCCIH lists sedatives and anti-seizure medicines among ashwagandha's possible interactions. If you take an antidepressant or any other medicine that affects mood or sleep, ask your prescriber before adding it, and stop if you notice a change in mood you don't like.

Pregnancy and breastfeeding

NCCIH advises that ashwagandha should be avoided during pregnancy and should not be used while breastfeeding. Treat this as a firm rule rather than a soft suggestion.

Autoimmune conditions

NCCIH says ashwagandha is not recommended for people with autoimmune disorders, and it may interact with immunosuppressant medicines. If you have a condition such as rheumatoid arthritis, lupus or Hashimoto's thyroiditis, speak to your specialist before using it.

Surgery

NCCIH also says it is not recommended for people who are about to have surgery. Tell your surgical team about any supplements you take, and follow their advice on when to stop.

Medicine interactions

NCCIH lists evidence that ashwagandha might interact with medicines for diabetes and high blood pressure, immunosuppressants, sedatives, anti-seizure medicines (anticonvulsants) and thyroid hormone medicines. Because it may raise testosterone, people with hormone-sensitive prostate cancer should avoid it. Given its sedative side effect, combining it with alcohol or other sedating products is also best avoided. If you take any prescription medicine regularly, check with a pharmacist before adding ashwagandha.

Side effect summary table

If you're deciding between the two best-known branded extracts, our comparison ofKSM-66 vs Sensoril is a useful companion; no difference in safety between them has been established, so every caution here applies to both. If you want the doses the trials actually used, seeKSM-66 dosage and timing, and for what ashwagandha has and has not been shown to do,ashwagandha benefits and dosage.

For further reading on the safety evidence, seeNCCIH's ashwagandha page, theNIH Office of Dietary Supplements general resources on supplement safety, and the case reports indexed onPubMed.

A practical safety checklist before starting

• Confirm you are not pregnant or breastfeeding.
• If you have any thyroid condition or take thyroid medication, speak to your doctor first.
• Review your current medicines with a pharmacist, particularly diabetes, blood-pressure, immunosuppressant, sedative, anti-seizure and thyroid medicines.
• Tell your surgical team if you have an operation planned.
• Use a dose from a trial of the extract you are buying, taken with food.
• Watch for jaundice, dark urine, itching, unusual tiredness or abdominal pain, and stop immediately if these occur.
• Avoid combining it with alcohol or other sedatives.
• Plan to reassess after about three months, the limit of the safety data NCCIH cites.

Key takeaways

• The most common side effects in trials are mild — sleepiness, stomach discomfort and loose stools.
• Liver injury is rare but documented in case series; stop and seek care if liver symptoms appear.
• Ashwagandha can raise thyroid hormone levels, which matters for anyone with a thyroid disorder or on thyroid medication.
• NCCIH advises avoiding it in pregnancy and breastfeeding, before surgery, and with autoimmune or thyroid disorders, and lists several medicine interactions.
• Safety beyond about three months has not been established. None of this is medical advice — check with a clinician or pharmacist if any of it applies to you.

Common questions

Is ashwagandha safe for daily long-term use?

NCCIH says it may be safe for up to three months and that there is not enough information to judge longer use. Most trials ran eight to twelve weeks, so a break and a check-in with your doctor after that point is a sensible precaution.

Can ashwagandha damage my liver?

It can, rarely. Case series describe jaundice and cholestatic liver injury starting weeks to a few months after people began taking it, usually improving after stopping. Stop and see a doctor if you develop jaundice, dark urine, itching or abdominal pain.

Should I avoid ashwagandha if I have a thyroid condition?

NCCIH says it is not recommended for people with thyroid disorders, because it can raise thyroid hormone levels and may interact with thyroid medicines. Speak to your doctor before using it.

Can I take ashwagandha with antidepressants?

No trial has studied the combination. NCCIH lists sedatives among its possible interactions, so ask your prescriber first, especially if your medicine also makes you drowsy.