How long does ashwagandha take to work?

Most clinical trials show meaningful effects after 4–8 weeks of consistent daily use. A 2026 dose-response meta-analysis found that treatment periods exceeding eight weeks produced the strongest outcomes, particularly at doses of 500 mg/day or below. Do not expect results within the first week. If you notice no change after eight weeks, reassess dose and extract quality before discontinuing.

When is the best time to take ashwagandha?

Trials have used both morning and evening dosing without consistent evidence that timing significantly alters outcomes. Evening use is sometimes preferred by those using it primarily for sleep, given a plausible mild sedative effect. If you experience any drowsiness, shifting the dose to evening is sensible. Splitting the dose (e.g., 300 mg morning and 300 mg evening) is common in trials and may improve tolerability.

Can I take ashwagandha every day long-term?

Most clinical trials run for 8–12 weeks. Long-term safety data beyond this period is limited. The liver injury case series (Björnsson et al., 2020) included a patient who used ashwagandha for approximately two years, and the thyrotoxicosis case report (Kamal et al., 2022) involved two years of self-supplementation. A cautious approach is to use it for defined periods of no more than 8–12 weeks and then reassess. If you choose to use it continuously, monitor for any signs of liver disturbance (jaundice, dark urine, fatigue) and discuss with a clinician if you have pre-existing conditions.

Should I cycle ashwagandha?

There is no controlled trial evidence showing that cycling (taking periodic breaks) improves outcomes or reduces risks. Some practitioners recommend 8–12 weeks on followed by a 4-week break, on general principles of avoiding continuous supplementation with limited long-term data. This is a reasonable precaution given that most trial data extends only to 12 weeks, but it is not evidence-based guidance per se.

Is ashwagandha safe during pregnancy?

No. Ashwagandha is contraindicated in pregnancy. Animal studies have demonstrated uterotonic effects, and there are no controlled safety data in pregnant humans. It should not be taken during pregnancy, when actively trying to conceive, or during breastfeeding. Consult your GP or midwife if you have questions about any supplement during pregnancy.

Does ashwagandha interact with any medications?

The most clinically significant interaction is with thyroid medications. A pilot RCT found ashwagandha significantly increased thyroid hormone levels (TSH, T3, T4) in subclinical hypothyroid patients, and a case report documented thyrotoxicosis in a patient self-supplementing. Anyone taking levothyroxine or anti-thyroid drugs should not use ashwagandha without prior discussion with their prescribing doctor. Potential interactions with immunosuppressants, sedatives, and hepatotoxic drugs should also be considered. Disclose all supplements to your GP.

What is the risk of liver damage from ashwagandha?

A case series published in Liver International identified five cases of clinically significant liver injury attributed to ashwagandha, presenting as cholestatic or mixed-pattern hepatitis. All cases resolved within 1–5 months of stopping the supplement and none progressed to liver failure. The absolute risk cannot be quantified from a case series, but the signal is real and has been recognised by regulatory bodies. To minimise risk, use standardised extracts (not high-dose raw powder), stay within researched dose ranges (300–600 mg/day), avoid use if you have pre-existing liver disease or use alcohol heavily, and stop immediately if you develop jaundice, dark urine, or unexplained fatigue.

What is the difference between KSM-66 and Sensoril?

KSM-66 is a full-spectrum root-only extract standardised to at least 5% withanolides, produced using a milk-based extraction process. It has the broadest trial record, covering stress, cortisol, testosterone, and sleep endpoints. Sensoril is an aqueous root-and-leaf extract standardised to 10% withanolides and 32% oligosaccharides — a different bioactive profile. The best Sensoril-specific RCT (the STAR trial) focused on strength and body composition. Both are materially superior to unstandardised generic root powder. For general stress and sleep use, KSM-66 has more supporting data. For resistance training and body composition, Sensoril has a specific, well-designed trial behind it.

Ashwagandha: Stress, Sleep & Strength — What the Research Shows

Nutripedia Research Team14 April 2026

Ashwagandha is one of the most-researched adaptogens in supplement form. Multiple meta-analyses confirm meaningful reductions in cortisol and perceived stress. Here is what the clinical evidence actually shows — including the safety signals you should know about before buying.

Not medical advice

Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice. Product mentions are not endorsements.

What Is Ashwagandha?

Ashwagandha (Withania somnifera) is a root herb that has been used in Ayurvedic medicine for over 3,000 years. In modern supplement research it is classified as an adaptogen — a compound proposed to help the body modulate its response to physical and psychological stress. The root contains a family of steroidal lactones called withanolides, which are considered the primary bioactive constituents responsible for its pharmacological effects. Withanolide content varies substantially between raw root powder, standardised root extracts, and aqueous root-and-leaf extracts, which is why the extract type and standardisation percentage printed on a product label matters considerably. Most clinical trials use either KSM-66, a full-spectrum root extract standardised to a minimum of 5% withanolides, or Sensoril, an aqueous root-and-leaf extract standardised to 10% withanolides and 32% oligosaccharides. Generic ashwagandha root powder is rarely standardised and has featured in fewer controlled trials. The proposed mechanism of action centres on modulation of the hypothalamic-pituitary-adrenal (HPA) axis — the hormonal cascade that governs the cortisol stress response. Withanolides are also thought to exert mild GABAergic activity, which may partly account for reported anxiolytic and sleep effects. Neither mechanism is fully characterised in humans.

Our research is based on 30 peer-reviewed studies. View the full evidence database

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Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Product mentions are not endorsements. Consult a healthcare professional before starting any supplement.

Reviewed by

Archie Roberts

Founder, Nutripedia — ALDR Ltd

This page summarises published research from PubMed, NHS, EFSA, and SACN. It does not constitute medical advice; consult a qualified healthcare professional before changing any supplement regimen.

Last reviewed: 14 Apr 2026Methodology