Ashwagandha influences several hormonal systems at once, most notably by lowering cortisol, raising testosterone in men, supporting thyroid hormones, and shifting reproductive hormones in women. These effects stem largely from its ability to calm the body’s central stress-response system, which in turn ripples out to other hormone pathways. Most changes show up after about 8 weeks of consistent use at 300 to 600 mg per day of a root extract standardized to 5% withanolides.
How It Lowers Cortisol
Cortisol is the hormone your adrenal glands release when you’re stressed. Ashwagandha’s best-documented hormonal effect is bringing that level down. In a randomized, placebo-controlled trial published in Medicine, participants taking ashwagandha saw a 23% drop in fasting morning cortisol over 8 weeks, while the placebo group stayed essentially flat (a 0.5% increase). The reduction was consistent across sexes: 25% in women and 22% in men.
The mechanism centers on the body’s stress-command chain, which runs from the brain’s hypothalamus to the pituitary gland to the adrenal glands. When you’re chronically stressed, this chain stays switched on, pumping out cortisol. Ashwagandha appears to dial down activity along that entire chain. Some of its active plant compounds may bind directly to the brain’s cortisol receptors, mimicking mild adrenal hormones and signaling the brain to stop requesting more. The result is lower cortisol output without suppressing your ability to respond to genuine emergencies.
There’s a secondary pathway involved too. Ashwagandha’s active compounds bind to GABA receptors in the brain, the same calming receptors targeted by anti-anxiety medications. By increasing GABA activity and serotonin receptor expression, it promotes better sleep and a calmer baseline nervous system, both of which reduce the upstream signals that trigger cortisol release in the first place. A systematic review found that 250 to 500 mg daily for 4 to 13 weeks significantly decreased morning cortisol in adults with elevated stress.
Testosterone and Male Reproductive Hormones
In men, ashwagandha consistently raises testosterone and DHEA-S, a precursor hormone the body converts into both testosterone and estrogen. A crossover trial in aging, overweight men found that 8 weeks of supplementation produced 14.7% higher testosterone and 18% higher DHEA-S compared to the same men during a placebo period. Because this was a crossover design, where each participant served as his own control, the findings carry extra weight.
The testosterone boost appears to work through two routes. First, by lowering cortisol. Cortisol and testosterone have an inverse relationship: when one rises, the other tends to fall. Chronic stress suppresses the brain signals (luteinizing hormone and follicle-stimulating hormone) that tell the testes to produce testosterone. As ashwagandha calms that stress axis, those signals recover. A meta-analysis of four clinical trials confirmed increases in both luteinizing hormone and testosterone, along with improvements in sperm concentration, semen volume, and sperm motility in men with low sperm counts.
Effects on Female Hormones
Research on women’s hormones is newer but promising. A randomized, placebo-controlled trial in menopausal women found that 8 weeks of ashwagandha root extract significantly increased estradiol and progesterone while reducing FSH and LH. Those shifts matter because menopause is defined by falling estradiol and rising FSH, so ashwagandha appeared to partially counteract that pattern. Women in the treatment group also experienced fewer hot flashes, lower perceived stress, and better quality-of-life scores.
The cortisol connection matters here too. Elevated cortisol can disrupt the menstrual cycle and suppress progesterone production in premenopausal women. By bringing cortisol down, ashwagandha may create conditions that allow reproductive hormones to normalize. This is not the same as hormone replacement therapy, and the magnitude of change is smaller, but it suggests a meaningful shift for women dealing with stress-related hormonal disruption or menopausal symptoms.
Thyroid Hormone Changes
Ashwagandha has a notable effect on thyroid function, which makes it useful for some people and potentially risky for others. In a trial of 50 adults with subclinical hypothyroidism (mildly elevated TSH but no full-blown thyroid disease), 8 weeks of supplementation significantly improved TSH, T3, and T4 levels compared to placebo. By the end of the trial, thyroid indices had effectively normalized.
This is worth paying attention to if you already take thyroid medication or have an overactive thyroid. Case reports have documented thyrotoxicosis, a dangerous excess of thyroid hormones, in people taking ashwagandha. One published case showed a patient’s TSH crashing to nearly undetectable levels while on the supplement. After stopping it, TSH returned to normal range within about five weeks. If you have any thyroid condition, this is a supplement to discuss with your doctor before starting.
Blood Sugar and Insulin
Ashwagandha may also influence metabolic hormones, though the evidence is thinner here. Systematic reviews indicate it can help restore altered blood glucose and HbA1c (a marker of average blood sugar over 2 to 3 months) without major safety concerns. Early clinical trials suggest it may improve insulin sensitivity, meaning your cells respond better to insulin rather than requiring more of it. These findings are preliminary, and ashwagandha shouldn’t replace any diabetes management plan, but the metabolic effects add another dimension to its hormonal profile.
How Long It Takes to Work
Hormonal changes from ashwagandha are not immediate. Most clinical trials measure outcomes at the 8-week mark, and that’s consistently where significant shifts in cortisol, testosterone, thyroid hormones, and reproductive hormones appear. Some stress-related benefits, like better sleep and reduced anxiety, may show up sooner because of the GABA receptor activity, which is more of a direct calming effect than a hormonal one. But for measurable changes on a blood test, plan on at least two months of daily use.
The dosing used across these trials typically falls between 300 and 600 mg per day of a root extract standardized to 5% withanolides. An international task force convened by the World Federation of Societies of Biological Psychiatry provisionally recommends that same range. Lower doses (around 250 mg) have also shown cortisol-lowering effects in some studies, but the 300 to 600 mg range has the most consistent support.
Who Should Be Cautious
Because ashwagandha genuinely moves hormone levels, it’s not a neutral supplement for everyone. People with hyperthyroidism or Graves’ disease risk pushing thyroid hormones dangerously high. Those on thyroid medication may find their dosage needs change. Hormone-sensitive conditions, including certain breast and prostate cancers, deserve caution given ashwagandha’s effects on estradiol, testosterone, and DHEA-S. Pregnant women are generally advised to avoid it, as its hormonal activity has not been studied in pregnancy. For most healthy adults dealing with stress, the safety profile in trials up to 13 weeks has been reassuring, with no serious adverse effects reported at standard doses.