Ashwagandha

What it is

Ashwagandha (Withania somnifera) is a root used in traditional Indian practice, now studied as a standardized extract. The working model is that its withanolide compounds moderate the stress response: across trials of 240–600 mg per day, supplemented groups reported lower perceived stress and showed modestly lower cortisol over 6–12 weeks. Sleep support appears to ride on the stress effect.

Two honest caveats shape our grading. Most trials come from a small network of research groups, so we hold the grade at B pending independent replication. And ashwagandha carries a longer interaction list than most supplements here — serotonergic medication, thyroid medication, pregnancy, sedatives, and rare reports of liver stress. Read the cautions before the evidence table.

Evidence by goal

• BB — one solid RCT or consistent meta-analytic signal Stress

  Root extract at 240–600 mg per day lowered perceived-stress scores and cortisol versus placebo across several trials, with larger effects at 600 mg; pooled results agree but heterogeneity is substantial.

  Chandrasekhar K, 2012 · Lopresti AL, 2019 · Salve J, 2019 · Meta-analysis of 12 RCTs of ashwagandha on stress and anxiety-scale scores, 2022

• B Sleep

  In one ten-week trial, 300 mg twice daily shortened time to fall asleep and improved sleep efficiency and rated sleep quality versus placebo.

  Langade D, 2019

Forms compared

• Standardized root extract. Extracts standardized to withanolide content (commonly 5%) carry most of the trial evidence. Match the label to the trial range: 240–600 mg per day.
• Whole root powder. The traditional preparation. Doses used traditionally are much higher and less consistent than extract trials — hard to map to the evidence.

Dose and timing

300–600 mg of standardized root extract daily, with food, for 6–12 weeks before judging. Morning or evening both appear in trials; if sleep is the target, evening dosing fits the use.

Evidence-backed range: 300–600 mg per day.

Cautions and interactions

• Avoid during pregnancy and nursing — traditional sources and animal data raise concerns, and no safety trials exist.
• If you take sertraline or any SSRI, do not combine on your own: ashwagandha may amplify serotonergic activity. Our recommender excludes the pairing outright — your prescriber can judge your specific case.
• If you take thyroid medication, involve the clinician who manages your dose — ashwagandha can nudge thyroid hormone levels and shift how a stable dose lands.
• Rare reports link ashwagandha to liver stress. Stop and seek care for dark urine, pale stools, or yellowing skin, and use extra caution if your liver function is reduced.
• It may add to the effect of benzodiazepines and other sedatives — expect stronger drowsiness if combined, and tell your prescriber.

From our interaction tables

• avoid Sertraline (Zoloft). Ashwagandha may amplify serotonergic activity alongside sertraline. We exclude it rather than guess at a safe overlap — talk to your prescriber before combining.
• avoid SSRIs (class). Ashwagandha may amplify serotonergic activity alongside any SSRI. We exclude it for the whole class — your prescriber can judge your specific case.
• avoid Pregnancy. Traditional sources and animal data raise concerns about ashwagandha in pregnancy, and no safety trials exist. We exclude it.
• avoid Nursing / breastfeeding. No safety data exist for ashwagandha while nursing. We exclude it.
• caution Levothyroxine (Synthroid). Ashwagandha can nudge thyroid hormone levels, which can shift how a stable levothyroxine dose lands. If you add it, involve the clinician who manages your dose.
• caution Reduced liver function. Rare case reports link ashwagandha to liver stress. With reduced liver function, use it only with clinician oversight and stop at any warning sign.
• caution Benzodiazepines (class). Ashwagandha may add to the sedative effect of benzodiazepines. If combined, expect stronger drowsiness and involve your prescriber.
• monitor Metformin. Ashwagandha may modestly lower blood glucose, which can stack with metformin. Watch your readings when starting or stopping it.

Who should skip this

• People who are pregnant or nursing.
• People taking an SSRI or other serotonergic medication, unless their prescriber approves the combination.
• People with reduced liver function, or a history of liver trouble with herbal extracts.
• People on thyroid medication who cannot involve their clinician in monitoring.

Questions we actually get

How long before it does anything?

The trials ran 6–12 weeks. Expect nothing meaningful from a few days of use; judge at the six-week mark.

Morning or evening?

Either appears in the trial record. If you are taking it mainly for sleep quality, evening with food is the sensible default.

Can I take it with my antidepressant?

Not on your own. Ashwagandha may amplify serotonergic medication, which is why our recommender excludes the pairing. Bring it to your prescriber — this is exactly the conversation they are for.

Is the liver concern serious?

Reports are rare but documented. Buy third-party-tested extract, stop at any warning sign — dark urine, pale stools, yellowing skin — and get seen promptly if one appears.

Sources

1. Chandrasekhar K, Kapoor J, Anishetty S, Indian Journal of Psychological Medicine, 2012 — RCT of full-spectrum root extract under chronic stress
2. Lopresti AL, Smith SJ, Malvi H, Kodgule R, Medicine (Baltimore), 2019 — RCT of ashwagandha in stressed adults
3. Salve J, Pate S, Debnath K, Langade D, Cureus, 2019 — dose-ranging RCT (250 vs 600 mg/day)
4. Meta-analysis of 12 RCTs of ashwagandha on stress and anxiety-scale scores, Phytotherapy Research, 2022
5. Langade D, Kanchi S, Salve J, et al., Cureus, 2019 — RCT of ashwagandha and sleep quality