What Does Ashwagandha Do to Your Body? Effects, Evidence & Dosage
Automated draft updated
Ashwagandha (Withania somnifera) is an adaptogenic herb that works primarily by modulating the body's stress-response system, reducing cortisol levels and supporting hormonal balance. Clinical research supports its use for stress, sleep quality, and physical performance, with effects typically emerging after 4–8 weeks of consistent use.
How Ashwagandha Works in the Body
The active compounds in ashwagandha are withanolides — steroidal lactones concentrated in the root and, to a lesser extent, the leaves. These compounds interact with the hypothalamic-pituitary-adrenal (HPA) axis, the system that governs cortisol production during stress. By down-regulating excessive HPA activity, ashwagandha helps the body return to a calmer baseline rather than remaining in a prolonged stress state. Withanolides also appear to modulate GABA receptors in the brain, which partly explains the herb's calming and sleep-supportive effects.
Standardised extracts such as KSM-66 ashwagandha root extract and Sensoril ashwagandha are designed to guarantee a consistent withanolide content per dose, making them the most reliably studied forms.
What the Clinical Evidence Shows
Across multiple randomised controlled trials, ashwagandha has demonstrated statistically significant effects in several areas:
- Stress and cortisol: A 2019 study using KSM-66 found serum cortisol reduced by ~27% versus placebo after 60 days, alongside self-reported reductions in perceived stress.
- Sleep quality: Participants taking Sensoril ashwagandha (leaf-and-root extract) reported faster sleep onset and improved sleep efficiency in a double-blind trial.
- Physical performance: Research on Shoden ashwagandha (35% withanolides) — one of the highest-concentration extracts available — showed improvements in muscle recovery and testosterone levels in resistance-trained men.
- Cognitive function: Pilot studies suggest ashwagandha may support working memory and reaction time, likely through its antioxidant and anti-neuroinflammatory properties.
- Thyroid and hormonal balance: Some evidence indicates ashwagandha may support thyroid hormone levels (T3/T4) in subclinical hypothyroidism, though this area requires further large-scale trials.
Effect sizes are generally moderate. Ashwagandha is not a pharmaceutical replacement, but as a daily supplement it has a meaningful and well-documented signal in the above areas.
Dosage Guidance
Effective doses vary by extract type:
- Full-spectrum root extracts (e.g., Himalayan ashwagandha, wild ashwagandha): typically 300–600 mg/day
- High-concentration standardised extracts (e.g., Shoden 35% withanolides): 120–240 mg/day due to higher withanolide density
- Sensoril (leaf-root blend): 125–250 mg/day
- KSM-66 (root-only): 300–600 mg/day
Taking ashwagandha with food — particularly a meal containing fat — may improve absorption of withanolides. For sleep support, an evening dose is often preferred; for energy and cognitive effects, morning dosing may be more practical.
Safety and Considerations
Ashwagandha has a well-established short-term safety profile at standard doses. Reported side effects are generally mild and include gastrointestinal discomfort, especially on an empty stomach. A small number of case reports have linked very high doses or prolonged use to elevated liver enzymes; this appears rare and typically resolves on discontinuation.
Contraindications to discuss with a clinician:
- Pregnancy (traditionally contraindicated; may stimulate uterine contractions)
- Autoimmune conditions (immunomodulatory effects may be relevant)
- Thyroid medications (potential additive effects)
- Sedative medications (possible synergy via GABA pathways)
Cycling use — for example, 8–12 weeks on followed by a 4-week break — is a common precautionary approach, though evidence on long-term continuous use is still accumulating.
Practical Use: Forms and Formats
Beyond capsules, ashwagandha is available in several formats. Ashwagandha tea and herbal ashwagandha latte blends offer lower, more gradual dosing suitable for daily ritual use. Ashwagandharishta is a traditional Ayurvedic liquid formulation using fermented ashwagandha, which may enhance bioavailability. For clinical-level outcomes, standardised capsule extracts remain the most evidence-backed delivery format.
Related Topics
Explore how ashwagandha intersects with these health areas:
Frequently asked questions
How long does ashwagandha take to work?
Most clinical trials show meaningful effects on stress and sleep after 4–8 weeks of daily use. Some individuals notice reduced anxiety or improved sleep quality within the first 1–2 weeks, particularly at higher doses. Consistent daily intake is more important than timing for long-term results.
Does ashwagandha affect hormones?
Yes — ashwagandha primarily reduces cortisol, the body's main stress hormone, by modulating the HPA axis. Research also suggests it may modestly increase testosterone in men under physical or psychological stress, and some studies indicate a supportive effect on thyroid hormone levels. These hormonal effects are generally mild and context-dependent.
Can you take ashwagandha every day?
Daily use for up to 60–90 days is considered safe and well-tolerated based on available clinical data. Many practitioners recommend a periodic break — such as 4 weeks off after every 8–12 weeks on — as a precautionary measure, though evidence mandating this is limited. Consult a healthcare provider if you have liver conditions or take prescription medications.
What is the difference between KSM-66 and Sensoril ashwagandha?
KSM-66 is a root-only extract standardised to at least 5% withanolides and is more commonly studied for physical performance, energy, and testosterone support. Sensoril uses both root and leaf material, is standardised to a higher withanolide percentage, and tends to appear in research focused on stress reduction and sleep quality. Both are reputable, patented forms with solid clinical backing.