Does ashwagandha increase testosterone?

The honest answer is 'a little, and indirectly' — not the direct testosterone booster the marketing implies. Ashwagandha's primary, well-supported effect is lowering cortisol: Huberman calls it 'highly effective at reducing cortisol' at 300mg twice daily. Because chronically high stress and cortisol can suppress testosterone, bringing cortisol down can let testosterone drift back up — which is why Huberman lists ashwagandha under 'hormone support' (alongside shilajit and tongkat ali) and says it 'can indirectly support testosterone and libido.'

The key words are indirectly and modestly. The effect is clearest in men who are chronically stressed or have low baseline testosterone; it is not a replacement for TRT, and it won't turn a normal, well-rested man into a high-testosterone outlier. Some human studies show small testosterone increases in stressed or infertile men, consistent with the cortisol mechanism.

Huberman is unusually explicit about caution here: because ashwagandha touches hormonal and thyroid pathways, he recommends cycling off after about 30 days and monitoring via bloodwork, and he and Dr. Andy Galpin stress 'careful, data-driven application rather than prophylactic use.' So if you're taking ashwagandha specifically for testosterone: treat it as a stress-and-cortisol tool that may modestly help, dose it at 300mg twice daily, cycle it, and check your labs — don't expect a dramatic hormonal swing.