Ashwagandha

Is ashwagandha safe?

For most healthy adults taking a standard root extract for a few weeks, side effects are mild: drowsiness, an upset stomach, sometimes diarrhoea. That is the picture from the many short trials behind its popularity as a stress and sleep remedy. The NIH's complementary health centre puts it plainly: it may be safe for up to three months, and there is not enough evidence on longer use.

Three things lower its score. It can injure the liver, rarely. It acts on hormones, including thyroid hormones. And it is now the most regulated popular herb in Europe.

Liver injury

Ashwagandha has a LiverToxLiverToxA free US National Institutes of Health database that summarises what is known about liver injury caused by medicines, herbs and supplements.More in the glossary likelihood score of C, which means a probable rare cause of clinically apparent liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary. The case that brought this to attention was a 2020 series in Liver International: five patients from Iceland and the US Drug-Induced Liver Injury Network developed jaundice 2 to 12 weeks after starting ashwagandha. They had nausea, tiredness, itching and abdominal discomfort. None developed liver failure, and in four of them liver tests returned to normal within one to five months.

More cases have been reported since, from India, Europe and the US, and the Dutch public health institute RIVM cited liver harm when it advised against ashwagandha in 2024. The absolute risk is unknown because nobody counts how many people take it. What is clear is the pattern: cholestatic injury (bile flow is blocked, causing jaundice and itching) starting within three months.

Stop taking it and see a doctor if you notice yellow skin or eyes, dark urine, pale stools or unexplained itching.

Thyroid, hormones and pregnancy

Ashwagandha can raise thyroid hormone levels. That is a problem if you have an overactive thyroid, and it can upset the dose balance if you take levothyroxine. It can also raise testosterone, so NCCIH advises men with hormone-sensitive prostate cancer to avoid it.

Pregnancy is the biggest red line. Traditional texts describe it as a possible abortifacient, and although modern supporters call this overstated, there are no safety data in pregnancy. Australia's TGA requires a pregnancy warning on most products.

Why Europe is cracking down

Year	Regulator	Action
2013	Germany (BfR)	Called for an EU safety review, citing hormone effects and missing data
2020	Denmark (DTU)	Found no basis to set a safe intake level
2020	Australia (TGA)	Mandatory pregnancy warning
2023	Denmark	Banned in food supplements, alerted other EU states
2024	Netherlands (RIVM)	Advised against use
2024	UK (FSA)	Called for evidence on safety
2026	India	Moved to ban leaf use; courts paused the ban

Sweden, Finland and France have also examined it, and an EU-level restriction is under discussion. The supplement industry argues that the concerns rely on old studies and leaf extracts, and points to trials at high doses for up to a year without serious harm. Our view: the evidence of harm is not overwhelming, but the regulators have a point that long-term safety has never been properly shown.

What is in the capsule

Ashwagandha products vary widely. Some use only the root, some include leaves (which contain more of certain withanolides, the active compounds), and extract strength ranges from a few percent withanolides to much more. Independent testing of ashwagandha specifically is limited. A US study published in JAMA in 2008 found lead, mercury or arsenic in about one in five Ayurvedic medicines bought online, so buy from a maker that publishes heavy metal testing, or one carrying a USP or NSF mark.

Who should not take it without medical advice

• Pregnant or breastfeeding women: avoid.
• People with thyroid disease, or taking levothyroxine.
• People with autoimmune diseases, or on immunosuppressants after a transplant.
• People with liver disease, or who drink heavily.
• Anyone on sedatives, anticonvulsants, or diabetes or blood pressure medicines.
• Anyone having surgery in the next two weeks.

Taking ashwagandha with other sedating supplements, such as melatonin or kava, adds to drowsiness, and kava carries its own liver risk. If any point on the list applies to you, talk to your doctor or pharmacist before you start.

How we scored it

Dose safety (70) reflects mild short-term side effects and unknown long-term effects. Organ toxicity (55) and regulatory actions (40) are the weakest factors: repeated liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary reports and a national ban. It scores close to turmeric, another popular herb with an emerging liver signal.