Ashwagandha Side Effects: Liver, Thyroid and Interactions

Ashwagandha is widely described as safe because most clinical trials report few serious problems over six to twelve weeks. That is useful evidence, but it is not the whole safety picture. Trials are often too small and too short to detect rare reactions.

This guide separates common tolerability issues from the more serious warning signs. If you are still deciding whether the potential benefits justify those risks, read the evidence-based Ashwagandha benefits guide and then compare products in the 2026 UK buyer's guide.

Common Ashwagandha side effects

Across short controlled trials, Ashwagandha is usually tolerated reasonably well. The side effects most often discussed by official evidence summaries are gastrointestinal discomfort, nausea, loose stools and drowsiness. Headache and dizziness are also reported in some studies or post-market accounts.

Can Ashwagandha affect the liver?

Yes, rare Ashwagandha-associated liver injury is now a credible safety signal. It is still uncommon relative to widespread use, but “rare” does not mean imaginary.

A 2026 scoping review identified 25 patients across 13 published reports. Injury typically appeared after weeks of use, most often with a cholestatic or mixed pattern. Jaundice and itching were common presentations. Most patients recovered after stopping, but severe outcomes were reported, particularly among people with pre-existing cirrhosis.

The NIH LiverTox overview similarly describes onset commonly within roughly two to twelve weeks and advises avoiding Ashwagandha in people with cirrhosis or advanced chronic liver disease.

• Stop using the product and seek medical advice for yellow skin or eyes
• Treat dark urine, pale stools or widespread itching as warning signs
• Do not restart after suspected supplement-related liver injury without medical advice
• Tell clinicians about every supplement and blend you use, not only prescription medicines

Multi-ingredient products make causality harder to establish. A single-ingredient, clearly labelled formula cannot eliminate risk, but it makes exposure easier to identify.

Ashwagandha and thyroid function

Ashwagandha may affect thyroid hormone levels. Small studies and case reports have described changes in T3, T4 or TSH, including reports consistent with thyrotoxicosis in susceptible users. The evidence is not strong enough to use Ashwagandha as a thyroid treatment; it is strong enough to justify caution.

The NIH health-professional fact sheet advises against use in people with thyroid disorders and notes potential interaction with thyroid-hormone medication. A 2025 safety review also highlights thyroid and liver concerns in higher-risk populations.

Which medicines can interact with Ashwagandha?

Interaction evidence is not equally direct for every medicine. Some cautions come from pharmacology, case reports or the possibility of additive effects rather than large interaction trials. That uncertainty is a reason to check, not a reason to assume safety.

Who should avoid Ashwagandha?

Official summaries generally advise avoiding Ashwagandha during pregnancy and breastfeeding because adequate safety evidence is lacking and pregnancy-related risks have been raised. It should also be avoided or used only with clinical advice in people with advanced liver disease, thyroid disease or autoimmune conditions.

• Pregnant or breastfeeding people
• People with cirrhosis, active liver disease or previous Ashwagandha-related liver injury
• People with thyroid disease or taking thyroid medication
• People with autoimmune disease or taking immunosuppressants
• Anyone preparing for surgery
• Children unless specifically advised by an appropriate clinician

This is not a complete personalised list. A pharmacist can check the actual medicine combination rather than relying on a generic online interaction list.

What is the current UK safety position?

The Food Standards Agency issued a call for evidence on Ashwagandha safety. A UK government summary published in June 2026 says the evidence is being reviewed by the Committee on Toxicity to inform risk assessment and potential risk management.

This is not a UK ban. It does mean responsible articles should avoid saying Ashwagandha is completely safe or implying that a history of traditional use settles every modern extract and dose question.

How to reduce avoidable risk

• Choose a product that identifies the plant part, extract, daily dose and active standardisation
• Avoid proprietary blends that hide the Ashwagandha amount
• Do not exceed the labelled serving
• Introduce one new supplement at a time
• Record when you started and any symptoms
• Stop promptly for concerning symptoms
• Keep your GP or pharmacist informed about supplement use

The Ashwagandha buyer's guide includes safety and transparency as buying criteria rather than ranking products on strength alone. That is especially important for a high-strength extract.

Frequently asked questions

Can Ashwagandha cause liver damage?

Rare cases of clinically apparent liver injury have been reported. Most recover after stopping, but serious outcomes can occur, especially with pre-existing liver disease.

What are the first signs of liver trouble?

Yellow skin or eyes, dark urine, pale stools, widespread itching, unusual fatigue, nausea and right-sided abdominal discomfort can be warning signs. Stop the supplement and seek medical advice.

Can Ashwagandha affect the thyroid?

It may alter thyroid hormones in some people and can interact with thyroid treatment. Do not use it to self-treat thyroid symptoms.

Can Ashwagandha make anxiety worse?

Individual responses vary. Agitation, an unusual mood change or worsening symptoms are reasons to stop and seek advice rather than increasing the dose.

Is Ashwagandha safe every day?

Most trials are short, often six to twelve weeks. Long-term daily safety is less certain, so indefinite use should not be assumed risk-free.

Can I take Ashwagandha with antidepressants?

This needs an individual medicine check. Ask your prescriber or pharmacist rather than relying on a broad yes-or-no answer.

How do I choose a transparent product?

Use the UK buyer's guide to compare extract identity, active dose, warnings and label clarity.

Sources and further reading

• McIntyre et al. 2026 scoping review of Ashwagandha-associated liver injury
• NIH LiverTox: Ashwagandha
• NIH Office of Dietary Supplements Ashwagandha fact sheet
• 2025 review of reproductive, thyroid, immune and liver safety
• Large 2026 eight-week Ashwagandha safety trial
• UK government summary of Ashwagandha call for evidence
• Committee on Toxicity: herb-induced liver injury, July 2026

Editorial note: SuperDosed sells an Ashwagandha supplement. This article separates research findings from product information and cites primary studies or official guidance wherever possible. It provides general information, not medical advice, and does not claim that Ashwagandha prevents, treats or cures disease.