Ashwagandha: evidence, forms and safety

Ashwagandha (Withania somnifera) is a herb traditionally used in Ayurveda and sold today as a supplement, often described as an "adaptogen" said to help the body cope with stress. Some small, short-term studies suggest possible benefits for stress and sleep, but the evidence is low-quality and long-term safety is not established. There are also some important safety cautions — including rare reports of liver injury and a clear warning against use in pregnancy — so this guide covers safety in detail.

This is general information, not personalised medical advice. Ashwagandha is not a treatment for any disease. If you take medication or have a health condition, speak to a doctor before using it.

What is ashwagandha?

Ashwagandha is an evergreen shrub whose root is used in supplements. It is a long-standing part of Ayurvedic tradition and is now marketed widely for stress, sleep and general wellbeing. It is classed as an adaptogen — a loose, marketing term rather than a proven pharmacological category.

It is sold in many forms (see below), which differ in dose and preparation, making it hard to compare one product with another.

What does the evidence support?

Some small, short-term trials suggest ashwagandha may modestly help with stress and sleep, but the evidence is weak. According to the US National Center for Complementary and Integrative Health, some preparations may be helpful for insomnia and stress, while the evidence for anxiety is unclear.

Key caveats:

• Studies are generally small and short (often a few weeks to a couple of months), and use different preparations and doses.
• Long-term safety and effectiveness have not been established.
• Evidence for other claims — memory, "immune boosting", inflammation — is insufficient.

So while some people report feeling calmer or sleeping better, the science is preliminary, and ashwagandha is not a substitute for proven approaches to stress and sleep. For evidence-based steps you can take, see our guide to sleep and insomnia.

What forms does it come in?

Ashwagandha is sold as:

• Powder — to mix into drinks or food
• Capsules and tablets
• Gummies
• Liquid drops
• Tea — made from the root or root powder

Because products vary so much in strength and extract type, the dose on one label may be very different from another. This variability is one reason it's hard to draw firm conclusions and why caution is sensible.

What are the side effects and risks?

This matters, so here is an honest summary. Reported side effects and risks include:

• Common, milder effects — drowsiness, stomach upset, nausea, diarrhoea and vomiting.
• Liver injury — importantly, there have been a number of reported cases of liver injury linked to ashwagandha supplements. The NIH LiverTox resource describes cases typically appearing 2 to 12 weeks after starting, often with jaundice and itching; most settle after stopping, but serious cases have occurred. Stop and seek medical advice if you develop symptoms such as yellowing skin or eyes, dark urine, persistent nausea or abdominal pain.
• Drowsiness and sedation — be cautious if combining with sedatives, alcohol or sleep medicines, or before driving until you know how it affects you.

Are there specific cautions, including for women?

Yes. Several groups should avoid ashwagandha or use it only after medical advice:

• Pregnancy — ashwagandha should be avoided in pregnancy, as it has been associated with a risk of miscarriage.
• Breastfeeding — it is not recommended, as safety has not been established.
• Thyroid conditions — ashwagandha may affect thyroid hormone levels, so use caution if you have a thyroid disorder or take thyroid medication.
• Autoimmune conditions — caution is advised, and it may interact with immune-suppressing medicines.
• Before surgery — it is generally advised to stop ashwagandha beforehand because of its sedative effects.

The "side effects for women" searches usually relate to the pregnancy, breastfeeding and thyroid/hormonal cautions above — these are the key factual points rather than anything mysterious.

Ashwagandha can also interact with medicines for diabetes, blood pressure, anxiety, seizures and the immune system. Because of this, and the liver concern, talk to a doctor before using it — especially if you take any regular medication.

A supplement is not a substitute for a balanced diet, good sleep habits or medical care. If stress, low mood or sleep problems are affecting you, speak to a healthcare professional.

This page provides general, evidence-based information. It is not a substitute for advice from a qualified healthcare professional.