Is Ashwagandha Safe? UK Evidence-Based Safety Guide | Complete Nutrition

Ashwagandha

Is ashwagandha safe

For most healthy adults yes, at standard doses for up to 3 months. The clinical trial safety record is good. Rare cases of liver injury have been reported. Specific groups should avoid ashwagandha entirely including pregnant women, people with thyroid disease and people with pre-existing liver conditions. The UK Food Standards Agency is currently reviewing ashwagandha food supplements. Here is what the evidence actually shows.

Shop Ashwagandha Gummies Visit the Ashwagandha Hub

Updated:
May 2026

Written by:
Dominic Walton, MD

Reading time:
5 min

The full answer

What the research shows about ashwagandha safety

Ashwagandha has been used in Ayurvedic medicine for thousands of years and has been studied in modern clinical trials for the past 20 years. The safety profile is generally favourable but it is not a side-effect-free supplement. The honest picture includes common minor side effects, rare serious adverse events and specific exclusions worth knowing.

1. The clinical trial safety record is good

Across the 2025 PMC12242034 meta-analysis (488 participants) and the 2021 PLOS One sleep meta-analysis (400 participants), no serious adverse events were reported. The 2022 systematic review on hematological and biochemical markers (PMC10444651) found no concerning changes in blood markers across 10 trials. Most reported side effects were mild: nausea, loose stools, drowsiness, headache. These typically resolved without intervention or after dose reduction.

2. Rare cases of liver injury have been reported

The NIH LiverTox database (updated December 2024) lists ashwagandha as a likely cause of clinically apparent liver injury with a B causality score. First cases were reported in 2017 and the number of reports has been increasing. The Philips 2020 case series documented multiple cases of cholestatic hepatitis. Most cases occurred at doses of 500 mg or higher for several weeks or months. The Indian Journal of Gastroenterology and Akarali analyses both flag concern at prolonged daily use above 500 mg. The absolute risk is low but not zero.

3. Thyroid effects are real

Ashwagandha can raise T3 and T4 levels. Cleveland Clinic and NCCIH both list thyroid disease as a precaution. Women with Hashimoto's thyroiditis may experience worsening due to immune stimulation. Patients on levothyroxine may need dose adjustment if they start ashwagandha. The 2022 hormonal review found ashwagandha modulated thyroid hormone levels in multiple studies. Anyone with known thyroid disease should consult their GP before starting daily ashwagandha and may need thyroid function monitoring.

4. Drug and condition interactions matter

Ashwagandha may interact with diabetes medication (additive blood sugar lowering), thyroid medication (additive thyroid effects), sedatives including benzodiazepines (additive CNS depression), immunosuppressants (counteracting effect), antihypertensives (additive blood pressure lowering) and anticoagulants (theoretical interaction). The mechanism for some is documented, for others theoretical. Anyone on chronic medication should discuss ashwagandha with their GP before starting daily use.

5. UK regulatory position is currently under review

The UK Food Standards Agency issued a call for evidence in 2024 to inform a future risk assessment of ashwagandha food supplements. The FSA notes that there are no safe levels established in the UK and that risk assessments through literature reviews have shown associations with effects on thyroid hormone levels, hypoglycaemic effects and potential liver toxicity. Some EU countries including Denmark have restricted ashwagandha. The supplement remains legally available in the UK but may face future regulatory action.

How to use it safely

How to actually use ashwagandha safely in five steps

The supplement is generally safe for most healthy adults but specific safe-use practices reduce the small risks that do exist. Following this protocol matches what reasonable clinicians would advise.

Step 1. Check whether you are in an exclusion group

Do not use ashwagandha if you are pregnant, breastfeeding, trying to conceive, have pre-existing liver disease, have active autoimmune disease, have hyperthyroidism, take levothyroxine, take warfarin or other anticoagulants. The same applies if you have planned surgery within 2 weeks. If any apply, talk to your GP before any supplement use, not just ashwagandha.

Step 2. Use a clinically tested dose for a clinically tested duration

Take 300 mg to 600 mg of standardised root extract daily. Do not exceed 600 mg without medical guidance. Use it for up to 12 weeks then reassess. The clinical trial safety data extends to around 12 weeks of continuous use. Longer use is common in practice but less well studied. Periodic 2 to 4 week breaks every 3 to 6 months are reasonable practice.

Step 3. Choose a reputable standardised product

Look for KSM-66 or Sensoril branded extracts. Look for products specifying withanolide content (minimum 2.5 percent root extract or higher for branded). Products that do not specify the extract type or withanolide content may contain unknown contaminants or inadequate active ingredient. The 2024 AI-driven safety review (PMC12682666) found ashwagandha root has a better safety profile than non-root parts so root-only products are preferable.

Step 4. Monitor for warning signs

Stop the supplement and see your GP if you develop yellowing of skin or eyes, dark urine, right upper abdominal pain, persistent nausea or unexplained fatigue. These can indicate liver injury. Also stop if you develop palpitations, tremor, unexplained weight loss or heat intolerance suggesting thyroid overactivity. Most adverse events develop gradually so paying attention to changes matters.

Step 5. Inform your GP before any new prescription

If your GP prescribes new medication, tell them you are taking ashwagandha. This particularly applies to thyroid medication, diabetes medication, sedatives, blood thinners and blood pressure medication. The interaction risk is real even at standard supplement doses. Stop ashwagandha at least 2 weeks before any planned surgery or invasive medical procedure.

Standardised root extract gummy

Get a standardised ashwagandha extract from a UK supplier

Our Ashwagandha Gummies use standardised root extract at the clinically tested dose. The withanolide content is specified on the label. The product is manufactured in the UK to food supplement standards. Same active ingredient as the trials. Convenient daily format.

Shop Ashwagandha Gummies

For anyone wanting a standardised ashwagandha root extract from a UK supplier with specified withanolide content, our Ashwagandha Gummies deliver the clinically tested dose in a daily format. Same active ingredient as the trials. Same daily protocol. Much easier to take consistently than capsules or powders.

Safety

When ashwagandha is a problem

Even at standard doses ashwagandha has specific safety considerations. Stop the supplement and see your GP if any of the following apply.

Yellowing of the skin or eyes, dark urine, persistent right-sided abdominal pain or unexplained fatigue. These can signal liver injury which has been reported rarely (LiverTox 2024, B causality score).
Palpitations, tremor, heat intolerance or unintended weight loss. These can signal thyroid overactivity which ashwagandha can cause or worsen.
Worsening of an autoimmune condition including rheumatoid arthritis, lupus, Hashimoto's or multiple sclerosis. Ashwagandha can stimulate immune activity.
Persistent nausea, abdominal pain or loose stools. Mild gastrointestinal effects are common. Persistent ones may indicate something more serious or may need dose reduction.
Pregnancy, breastfeeding or active attempts to conceive. Stop at least 1 cycle before conception. Ashwagandha is not recommended in pregnancy.

Anyone on prescription medication particularly for thyroid, diabetes, autoimmune disease, blood pressure, anticoagulation or sedation should consult their GP before starting daily ashwagandha. The interaction risk is real even at standard supplement doses. People with pre-existing liver disease should avoid the supplement entirely.

For the wider picture on ashwagandha including detailed dosing, timing and efficacy, our Understanding Ashwagandha hub brings every guide together in one place.

Part of the hub

Back to the Ashwagandha Hub

This article sits inside our complete knowledge base on ashwagandha covering benefits, dosing, timing, side effects and the science behind withanolides. Head back to the hub for the full index.

Visit the Ashwagandha Hub

Keep reading

More on ashwagandha safety and use

Safety connects to several other guides. Are ashwagandha gummies safe for daily use covers daily use specifically. Common myths and misconceptions about ashwagandha covers misinformation around safety. And ashwagandha gummies vs capsules vs powders covers format choice.

Frequently asked

Ashwagandha safety questions

Is ashwagandha safe for daily use?

Generally yes for healthy adults at standard doses up to 600 mg per day for up to 12 weeks. Longer continuous use is common in practice but less well studied. The clinical trial safety record at 8 to 12 weeks is good. Periodic 2 to 4 week breaks every 3 to 6 months are reasonable practice. People with thyroid disease, autoimmune conditions, pregnancy or liver disease should not take it daily.

Does ashwagandha damage the liver?

Rarely yes. The NIH LiverTox database lists ashwagandha as a likely cause of clinically apparent liver injury with a B causality score. Cases have been reported since 2017 and the count is increasing. Most cases involve doses of 500 mg or higher for weeks or months. The absolute risk is low but not zero. Stop the supplement immediately if you develop yellowing of skin or eyes, dark urine or right upper abdominal pain. People with pre-existing liver disease should avoid ashwagandha entirely.

Can I take ashwagandha during pregnancy?

No. NCCIH, Cleveland Clinic and most clinical guidance advise against ashwagandha during pregnancy. Some evidence suggests it may stimulate uterine contractions which could theoretically increase miscarriage risk. There are no well-controlled trials in pregnant women so the safety profile is unknown. Stop the supplement immediately if you discover you are pregnant while taking it and inform your GP or midwife.

Does ashwagandha interact with antidepressants?

There is no major known dangerous interaction with SSRIs. The Rana 2020 trial specifically studied ashwagandha as an adjunct to SSRI treatment and found additional improvement without significant safety concerns. However, ashwagandha may enhance the sedative effect of some antidepressants particularly mirtazapine and trazodone. Talk to your GP before combining ashwagandha with prescribed antidepressants.

Can ashwagandha cause anxiety or panic attacks?

Uncommonly yes, particularly in people with undiagnosed hyperthyroidism. Ashwagandha can raise thyroid hormone levels which can itself cause anxiety symptoms. A small minority of users report worsened anxiety on the supplement. If you start ashwagandha and your anxiety gets worse rather than better, stop and see your GP. Thyroid function tests may identify an underlying issue.

What are the long-term side effects of ashwagandha?

Long-term safety beyond 3 to 6 months is poorly studied. Rare cases of liver injury have appeared at long-term high-dose use. Long-term thyroid effects are theoretically possible. The 2024 LiverTox update reflects accumulating concern but no definitive long-term risk profile exists. Conservative practice is to use the supplement in 8 to 12 week courses with periodic breaks rather than indefinite daily use.

Is the UK Food Standards Agency banning ashwagandha?

Not currently. The FSA issued a call for evidence in 2024 to inform a future risk assessment. The supplement remains legally available in the UK. The FSA has noted associations with thyroid effects, hypoglycaemic effects and potential liver toxicity. Some EU countries including Denmark have restricted ashwagandha. The UK position may change based on the outcome of the FSA review. For now consumers can continue to buy and use ashwagandha legally in the UK.