THE CALM SERIES · SAFETY GUIDE
Ashwagandha Side Effects, Interactions & Who Should Avoid It
Who should not take ashwagandha? A practical, evidence-led guide to side effects, contraindications, medication interactions, thyroid and autoimmune concerns, pregnancy, surgery, and rare liver injury.
A quick decision check
Do not use ashwagandha during pregnancy or breastfeeding. NCCIH also advises against use by people who are about to have surgery.
Get guidance if you have a thyroid or autoimmune disorder, a liver condition, or take prescription medicines—especially thyroid hormone, sedatives, anticonvulsants, immunosuppressants, or medicines for blood pressure or blood sugar.
If a symptom began after starting it, record when it started, the amount and timing used, other supplements or medicines added, and the exact product label.
Stop use and seek prompt medical care for yellow eyes or skin, dark urine, unusual itching, marked fatigue, severe or persistent nausea, vomiting or abdominal pain. Trouble breathing or swelling of the face, tongue or throat needs emergency help.
Ashwagandha is not a fit for everyone.
NIH's National Center for Complementary and Integrative Health says ashwagandha may be safe for many adults when used short term, up to about three months, but long-term safety is not established. It can cause drowsiness and gastrointestinal symptoms, has been linked to rare liver injury, and may interact with several medication classes.
Ashwagandha should be avoided during pregnancy and breastfeeding. NCCIH also does not recommend it for people about to have surgery or people with autoimmune or thyroid disorders. If you use prescription medication, review the combination with a clinician or pharmacist before adding it.
WHO SHOULD AVOID IT
Who should not take ashwagandha?
The clearest caution groups in current NIH guidance include people who are pregnant or breastfeeding, people approaching surgery, and people with autoimmune or thyroid disorders. NCCIH also advises caution for people using potentially interacting medications.
Having one of these conditions does not mean every exposure produces harm. It means self-directed supplementation is not the appropriate default. A healthcare professional who knows your diagnoses and medications can assess the individual risk.
COMMON EFFECTS
What are the most common ashwagandha side effects?
Commonly reported effects are usually gastrointestinal or sedating. NCCIH lists drowsiness, stomach upset, diarrhea, and vomiting. NIH's Office of Dietary Supplements also describes upset stomach, loose stools, nausea, and drowsiness as common mild effects.
Do not treat feeling sick as proof that a supplement is “working.” If symptoms are significant, persistent, or began after introducing the product, stop using it and seek appropriate medical guidance.
MEDICATION CHECK
What medications can interact with ashwagandha?
NCCIH says ashwagandha might interact with several medication categories. Interaction evidence varies in strength, so these should be treated as reasons to review the combination rather than proof that every pairing is dangerous.
Potential interaction; review the combination with your prescriber or pharmacist.
Potential interaction is specifically identified by NCCIH.
Relevant because ashwagandha may affect immune activity.
Ashwagandha itself can cause drowsiness in some people.
NCCIH lists anticonvulsants among potential interactions.
Ashwagandha may affect thyroid function and may interact with thyroid medication.
If you take prescription medication, do not stop or alter it because of an online interaction list. Ask a pharmacist or clinician to review the exact supplement, dose, and medication regimen.
THYROID
Ashwagandha and thyroid conditions
NCCIH does not recommend ashwagandha for people with thyroid disorders. NIH's Office of Dietary Supplements notes that studies suggest ashwagandha may affect thyroid function and therefore might interact with thyroid medications.
AUTOIMMUNE CONDITIONS
Ashwagandha and autoimmune conditions
NCCIH does not recommend ashwagandha for people with autoimmune disorders and also lists immunosuppressant medicines among potential drug interactions. If you have an autoimmune diagnosis or use medication intended to suppress immune activity, discuss ashwagandha with the clinician managing that condition before taking it.
PREGNANCY & BREASTFEEDING
Can you take ashwagandha while pregnant or breastfeeding?
Current NCCIH guidance is direct: ashwagandha should be avoided during pregnancy and should not be used while breastfeeding.
BEFORE SURGERY
Why should ashwagandha be avoided before surgery?
NCCIH does not recommend ashwagandha for people who are about to have surgery. Tell your surgical team about all supplements and herbal products you use and follow their instructions about when to discontinue them.
RARE BUT IMPORTANT
Can ashwagandha cause liver injury?
Rare cases of clinically apparent liver injury have been reported. NIH LiverTox describes cases that typically appeared within weeks of starting ashwagandha and notes that most reported cases resolved after discontinuation, although severe cases have occurred.
Yellowing of the skin or eyes, dark urine, severe or persistent nausea, unusual itching, marked fatigue, or significant abdominal symptoms warrant medical evaluation.
SEARCH QUESTIONS, ANSWERED
Quick ashwagandha safety FAQs
What are the main ashwagandha contraindications?
Pregnancy, breastfeeding, upcoming surgery, autoimmune disorders, and thyroid disorders are specifically identified in NCCIH safety guidance. Medication use can add additional interaction concerns.
Can ashwagandha interact with medications?
Potential interactions include diabetes and blood-pressure medicines, immunosuppressants, sedatives, anticonvulsants, and thyroid hormone medicines.
Can I take ashwagandha with thyroid medication?
NIH guidance notes that ashwagandha may affect thyroid function and might interact with thyroid medication. People with thyroid disorders should seek professional guidance rather than self-supplementing.
Is ashwagandha safe every day?
NCCIH says ashwagandha may be safe for short-term use up to about three months, but there is not enough information to draw conclusions about long-term safety.
When should I stop taking ashwagandha?
Stop and seek medical advice if you develop significant new symptoms after starting it. Possible liver-injury warning signs such as jaundice or dark urine warrant prompt medical evaluation.
KEEP READING
Put safety in context
PRIMARY REFERENCES
Sources
NIH/NCCIH — Ashwagandha: Usefulness and Safety
NIH Office of Dietary Supplements — Ashwagandha Consumer Fact Sheet
Reviewed September 11, 2026. This page is educational and is not medical advice. Dietary supplements are not intended to diagnose, treat, cure, or prevent disease.