What Does Ashwagandha Actually Do to Your Body?
Automated draft updated
Ashwagandha (Withania somnifera) is a clinically studied adaptogen that primarily works by modulating the hypothalamic-pituitary-adrenal (HPA) axis to reduce cortisol output and blunt the physiological stress response. Beyond stress, it exerts measurable effects on thyroid hormones, testosterone, muscle recovery, sleep quality, and inflammatory markers.
How Ashwagandha Works in the Body
The plant's active compounds — withanolides, withanosides, and alkaloids — are the primary drivers of its pharmacological effects. These steroidal lactones interact with GABA receptors in the brain (contributing to anxiolytic effects), suppress nuclear factor-kappa B (NF-κB) signalling to reduce inflammation, and appear to inhibit stress-induced rises in cortisol. High-withanolide extracts such as Shoden® (35% withanolides) and KSM-66® have been used in most human clinical trials, making them the best-characterised forms.
Evidence-Backed Effects
Stress and cortisol reduction: Multiple randomised controlled trials demonstrate that standardised ashwagandha extracts significantly lower serum cortisol (by approximately 14–30%) and self-reported stress scores over 8–12 weeks. Sensoril® (leaf and root extract) has shown particular efficacy for perceived stress in adult populations.
Sleep quality: Ashwagandha supplementation has been linked to improved sleep onset latency and sleep efficiency, likely through triethylene glycol and its GABAergic activity. Studies using KSM-66 ashwagandha root extract report meaningful improvements on validated sleep questionnaires.
Thyroid and hormonal support: Ashwagandha modestly raises T3 and T4 levels in subclinical hypothyroid populations and has been shown to increase testosterone and LH in men with low baseline levels. These effects appear dose- and duration-dependent.
Muscle strength and recovery: Several trials in resistance-trained adults report that Withania somnifera supplementation is associated with greater gains in muscle strength and faster recovery, potentially via reduced exercise-induced oxidative stress.
Cognitive function: Withanolides may support acetylcholine signalling and neuroplasticity. Early clinical data suggest improvements in reaction time, working memory, and attention, particularly under stress conditions.
Dosage Guidance
Effective doses in clinical trials range from 240 mg to 600 mg per day of a standardised root extract, taken in one or two divided doses. Higher withanolide content (≥5%) generally allows effective dosing at the lower end of this range — for example, Shoden® at 35% withanolides is studied at 120–240 mg/day. Whole-herb and less concentrated forms like Himalayan ashwagandha or ashwagandha tea may require higher gram-level quantities to deliver comparable withanolide loads. Most trials run 8–12 weeks; benefits appear to accumulate gradually rather than acutely.
Safety and Contraindications
Ashwagandha has a well-established safety profile at recommended doses in healthy adults. Reported side effects are generally mild and include gastrointestinal upset and, rarely, drowsiness. However, a small number of case reports have linked high-dose or prolonged use to liver injury, so caution is warranted in individuals with hepatic conditions. It is contraindicated during pregnancy due to potential uterotonic effects. Those on thyroid medication, immunosuppressants, or sedatives should consult a clinician before use, as pharmacological interactions are plausible given its thyroid-stimulating and CNS-modulating actions.
Practical Use
For most people seeking stress relief or sleep support, a root-only or root-and-leaf standardised extract (KSM-66, Sensoril, or Shoden) taken with food in the evening or split morning/evening offers the most evidence-backed approach. Culinary formats such as herbal ashwagandha latte or ashwagandha tea can provide a low-dose daily habit but are unlikely to replicate the effect sizes seen in clinical trials. Traditional Ayurvedic preparations like Ashwagandharishta combine ashwagandha with other herbs; their evidence base is less robust but they remain widely used in integrative practice.
---
Related Topics
Frequently asked questions
How long does ashwagandha take to work?
Most clinical trials report measurable improvements in stress, sleep, and cortisol levels after 4–8 weeks of consistent daily use, with peak effects typically observed at 8–12 weeks. Ashwagandha is not an acute anxiolytic; it works through gradual modulation of the HPA axis rather than immediate sedation.
Does ashwagandha actually lower cortisol?
Yes — multiple randomised controlled trials show statistically significant reductions in serum cortisol of roughly 14–30% with standardised extracts such as KSM-66 and Sensoril over 8 weeks. These reductions correlate with self-reported decreases in perceived stress and anxiety in the same studies.
Can ashwagandha affect hormones like testosterone or thyroid?
Evidence suggests ashwagandha can modestly raise testosterone in men with below-average baseline levels and may increase T3/T4 in people with subclinical hypothyroidism. These hormonal effects mean individuals already on thyroid medication or hormone therapy should seek medical guidance before supplementing.
Is it safe to take ashwagandha every day?
Daily use at recommended doses (240–600 mg standardised extract) appears safe for most healthy adults for periods of up to 12 weeks based on clinical trial data. Rare cases of liver injury have been reported, so periodic breaks and avoidance of very high doses are prudent, especially for those with liver conditions.