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Ashwagandha: Uses, Benefits, Dosage & Safety

Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy

Quick summary

Ashwagandha is an Ayurvedic adaptogen taken mainly for stress and sleep. It has a reasonable amount of human research for modest reductions in stress and anxiety, though study quality is uneven and it carries real cautions in pregnancy and thyroid disease.

What is Ashwagandha?

Ashwagandha (Withania somnifera) is a shrub whose root has been used for thousands of years in Ayurvedic medicine as a 'rasayana' or rejuvenating tonic. It is classed as an adaptogen, a loose term for substances thought to help the body cope with stress. Its active compounds are steroidal lactones called withanolides, and quality supplements (such as KSM-66 and Sensoril) are standardised to a withanolide percentage. It is sold for stress, sleep, energy and, in men, sometimes for vitality.

What Ashwagandha is commonly used for

In supplements, Ashwagandha is most often included for men's vitality & testosterone support. It is used as nutritional support, not as a treatment for any medical condition — the distinction matters, because the claims on a sales page are often stronger than the evidence allows.

How Ashwagandha works

Ashwagandha is thought to act partly by blunting the body's stress response, including modestly lowering the stress hormone cortisol, and by influencing calming neurotransmitter (GABA) activity. These mechanisms fit its traditional use for stress and sleep. The effect is generally gradual, building over weeks of daily use rather than acting like a fast sedative.

What the evidence says

Here's an honest snapshot of what published research suggests about Ashwagandha — including where the evidence is limited.

Typical dosage used in studies

Trials commonly use 300-600 mg/day of a root extract standardised to withanolides, taken for at least 6-8 weeks. This is research information, not a recommendation.

Side effects and safety

Ashwagandha is generally well tolerated short-term; the most common effects are stomach upset and drowsiness. Rare reports of liver injury exist, mostly with certain products, so unexplained nausea, dark urine or yellowing skin should prompt stopping and seeing a doctor.

Medication interactions and who should avoid Ashwagandha

Medication & safety check

Ashwagandha should be avoided in pregnancy (it has been linked to miscarriage). Because it can raise thyroid hormone levels and stimulate the immune system, people with thyroid conditions or autoimmune diseases, and those on thyroid or immunosuppressant medication, should check with a doctor. It may add to sedatives and should be stopped before surgery.

This is general information, not personal medical advice. If you take any medication, confirm it's safe to combine with Ashwagandha with your doctor or pharmacist first.

Sources & further reading

The evidence summary above is drawn from these sources. For general, authoritative background you can also consult:

Frequently asked questions

What is ashwagandha used for?

Most commonly for stress and sleep. The better evidence is for modest reductions in perceived stress and anxiety; other claims are less well supported.

How long does ashwagandha take to work?

Trials that show benefit usually run 6-12 weeks. It builds gradually rather than acting like a fast sedative.

Does ashwagandha raise testosterone?

Some small male-fertility studies show hormonal changes, but the evidence is limited and shouldn't be oversold. It is not a reliable testosterone booster.

Who should avoid ashwagandha?

Anyone pregnant, and people with thyroid or autoimmune conditions or on related medication, should avoid it or check with a doctor first.

Supplements that contain Ashwagandha

On FactoWiki, Ashwagandha appears in these reviewed products. Each review breaks down the full formula, pricing and safety.