hormones · 1 min read
Supplements to reduce cortisol: what holds up
Among supplements to reduce cortisol, ashwagandha has the most trial support and phosphatidylserine some; most of the rest rest on animal work. Behaviour still moves cortisol more than any capsule.
Written by Lifebar Desk · Checked against the sources listed below
Published 17 Aug 2026
Key takeaways
- Ashwagandha reduced cortisol by roughly 20 to 30% versus placebo in several small randomised trials.
- Phosphatidylserine blunts exercise-induced cortisol; evidence for chronic stress is thinner.
- Sleep, exercise dose and caffeine timing move cortisol more reliably than any supplement.
Cortisol is not a villain. It runs your waking rhythm, mobilises glucose and regulates inflammation. The problem people are describing is usually chronically elevated evening cortisol from stress and short sleep.
What has trial support
Ashwagandha (Withania somnifera). Several small randomised trials using 300 to 600 mg daily of standardised root extract report reductions in serum cortisol of roughly 20 to 30% versus placebo, alongside lower anxiety scores. Trials are small, often conducted in India, and several are industry-funded, the effect is plausible but not settled. It also carries rare reports of liver injury, so it is not a casual daily supplement.
Phosphatidylserine. Blunts cortisol response to intense exercise at 600 mg daily in small studies. Evidence for everyday stress is weaker.
Weak or preliminary
Rhodiola, holy basil, magnesium, omega-3s and L-theanine all have some mechanistic rationale and small, inconsistent human data. None have the replication to be called effective.
What actually moves cortisol
| Lever | Effect |
|---|---|
| Sleep extension | Normalises evening cortisol most reliably |
| Regular aerobic exercise | Lowers resting cortisol over weeks |
| Overtraining | Raises it, dose matters in both directions |
| Caffeine after midday | Raises evening cortisol and delays sleep |
| Alcohol | Raises overnight cortisol and heart rate |
A word on testing
Single morning serum cortisol tells you little on its own. If symptoms suggest a genuine endocrine problem, unexplained weight gain around the trunk, purple striae, muscle weakness, that warrants proper evaluation, not a supplement.
Frequently asked
Is high cortisol common?
Genuinely elevated cortisol from Cushing's syndrome is rare. Most people asking about "high cortisol" have symptoms of chronic stress and poor sleep, which is a different problem.
How long does ashwagandha take?
Trials typically dosed 300 to 600 mg of root extract daily for 8 weeks before measuring outcomes.
Sources
Educational content, talk to your clinician before changing treatment.
