Ashwagandha (Withania somnifera) is the most widely studied and most widely used classical Ayurvedic herb in modern global wellness markets. The Sanskrit name combines ashwa (horse) and gandha (smell), with the dual meaning of “the smell of a horse” (the fresh root has a faint equine odour) and “strength of a horse” (the herb’s classical reputation). The Latin species name somnifera means “sleep-inducing”. The Charaka Samhita Chikitsasthana 1.4 lists ashwagandha among the principal rasayanas; the Sushruta Samhita Sutrasthana 38 places it in the bala (strength-building) group of herbs. Modern research has documented effects on cortisol, anxiety, sleep, and physical performance. This article sets out the classical and modern uses, the standard dose, and the cautions that often get omitted in marketing.
Classical properties
- Rasa (taste): bitter (tikta), astringent (kashaya), sweet (madhura).
- Virya (potency): warming (ushna).
- Vipaka (post-digestive effect): sweet.
- Doshic effect: reduces vata and kapha; can increase pitta in excess.
- Classical actions: balya (strength-building), rasayana (rejuvenating), vajikarana (reproductive-tonic), nidrajanana (sleep-inducing), shothahara (anti-inflammatory).
- Tissue affinity: particularly affects muscle (mamsa), reproductive tissue (shukra), nervous tissue (majja), and bone marrow.
Classical indications
- Chronic stress and fatigue: the principal modern use, aligned with the classical use for depletion and weakness.
- Anxiety with depletion: particularly the presentation with insomnia, weight loss, and low energy.
- Insomnia from depletion: the somnifera in the Latin name reflects this classical use.
- Recovery from illness: as a rasayana after febrile illness, surgery, or chronic disease.
- Male reproductive health: vajikarana use for low libido, low sperm count, and erectile difficulties.
- Female reproductive health: in combination with shatavari, used for fertility and post-partum recovery.
- Sarcopenia and muscle wasting: the bala property supports muscle mass, particularly with age.
- Joint pain and arthritis: the anti-inflammatory action is documented in classical and modern texts.
- Hypothyroidism: classical use for the lethargy and weight gain pattern; modern research shows mild T3 and T4 increases.
Forms and dose
- Root powder (ashwagandha churna): half a teaspoon to one teaspoon (3 to 6 grams) twice daily with warm milk or water.
- Standardised extract (capsule): 300 to 600 mg twice daily of extract standardised to 2.5 to 5 percent withanolides. The dosage used in most modern clinical trials.
- KSM-66: a patented full-spectrum extract (5 percent withanolides), 300 to 600 mg twice daily; the form used in many recent trials.
- Sensoril: a patented leaf-and-root extract (10 percent withanolides), 125 to 250 mg twice daily.
- Ashwagandha ghrita: medicated ghee, one to two teaspoons twice daily, particularly for neurological and reproductive indications.
- Ashwagandhadi lehyam: a traditional confection used for muscular and reproductive support.
- Ashwagandharishta: fermented herbal preparation, 15 to 30 ml twice daily after meals.
What modern research has documented
- Significant reductions in salivary and serum cortisol after eight to twelve weeks of standardised extract; effect size is moderate.
- Improvements in self-reported anxiety scores in multiple trials, particularly for generalised anxiety.
- Improvements in sleep onset and sleep quality at 600 mg daily.
- Increases in testosterone in men with low baseline levels (typically infertile men or older men with low-normal levels); effects are smaller in younger men with normal levels.
- Improvements in sperm parameters in men with idiopathic infertility.
- Improvements in strength, muscle mass, and recovery in resistance training trials.
- Mild increases in T3 and T4 in subclinical hypothyroidism; caution required in those on thyroid medication.
- Anti-inflammatory effects documented in arthritis trials.
Cautions and contraindications
- Hyperthyroidism: contraindicated; ashwagandha increases thyroid hormones.
- Thyroid medication: ashwagandha can increase thyroid hormone effect; coordinate with prescriber.
- Pregnancy: contraindicated in classical texts; modern review confirms avoidance during pregnancy.
- Autoimmune disease: caution; ashwagandha is immunomodulatory and may aggravate certain conditions including hashimoto’s, lupus, rheumatoid arthritis.
- Sedative medication: additive sedation possible with benzodiazepines, barbiturates, sleep medication.
- Nightshade allergy: ashwagandha is in the Solanaceae family; rare cross-reactivity in those with nightshade sensitivity.
- Liver concerns: rare cases of hepatotoxicity have been reported in supplement databases; sourced root powder appears safer than concentrated extracts. Discontinue with any sign of liver disturbance.
- Surgery: discontinue two weeks before scheduled surgery due to potential sedative interactions with anesthesia.
A practical opinion on ashwagandha
For what it’s worth, the most defensible use of ashwagandha for the modern user is as a six-to-twelve-week course (not indefinite) for a defined presentation: chronic stress with depletion, sleep disruption, mild anxiety, or recovery from a difficult period. The classical use was as a rasayana taken in courses, with periodic pauses, not as a daily supplement taken for years. The trend of taking ashwagandha continuously as a “wellness habit” is outside the classical tradition and has limited long-term safety data. A defined trial, evaluation of response, and a pause is the structurally sound approach.
Common questions
Powder or extract?
The classical preparation is the root powder taken with warm milk. Standardised extracts (KSM-66, Sensoril) deliver more concentrated withanolides per dose and are more practical for capsule use, and most modern clinical trials use extracts. The classical use of milk as a vehicle is not incidental; the fat-soluble withanolides absorb better with milk fat. Powder with warm milk is the traditional form; extract in capsule is the modern convenient form. Both work; the trial data is stronger for extracts.
When during the day?
For sleep and anxiety: evening, ideally with warm milk thirty to sixty minutes before bed. For energy, strength, and physical performance: morning. Split-dose (morning and evening) is also common and is the form used in most clinical trials. Avoid on an empty stomach for the first two weeks if gastric upset occurs.
How long until effects?
Sleep improvements often appear in the first two weeks. Anxiety reduction typically takes four to six weeks. Cortisol changes are measurable at eight weeks. Strength and muscle effects require eight to twelve weeks. Reproductive effects (testosterone, sperm parameters, libido) typically require twelve to sixteen weeks. The classical view is that rasayana effects build gradually over a season of consistent use.
One limitation worth noting
Ashwagandha has documented effects but is not the universal supplement its marketing suggests. The clinical effects are real and modest; the marketing claims of dramatic transformation are not supported by the trial evidence. It is contraindicated in pregnancy, hyperthyroidism, and active autoimmune disease. The rare reports of hepatotoxicity, while uncommon, mean the supplement should be discontinued at any sign of liver disturbance. Source from reputable suppliers (FSSAI-certified in India, third-party-tested elsewhere); contamination has been documented in some commercial products.
For further reading see the Wikipedia entry on Withania somnifera and the Central Council for Research in Ayurvedic Sciences.
