Open Source Apothecary At Home / Mind and sleep

Stress, cortisol and the adaptogen category

Ashwagandha and rhodiola have small trials showing reduced stress measures. The category is a marketing term.

guide

The word "adaptogen" was coined to describe substances said to increase resistance to stress without disturbing normal function. It is a marketing category: there is no receptor, no agreed definition, and no regulatory standard, and the pooled evidence for the class is weaker than the marketing for any individual product.

Two plants have the most small trials:

Ashwagandha (Withania somnifera) — small randomised trials in stressed adults show reduced Perceived Stress Scale scores and reduced serum cortisol, over 8-12 week periods. The trials are small, several are industry-funded, and there are case reports of liver injury. It is also used traditionally as an abortifacient and is not for use in pregnancy. The evidence is genuinely mildly positive and the safety signal is genuine; both belong in the same sentence.

Rhodiola rosea — small trials showing reduced fatigue and improved measures of stress and, in some studies, exercise performance. Generally well tolerated; can be stimulating, so it is usually taken in the morning.

What the term hides. Because there is no standard, a product labelled "adaptogen blend" can contain subclinical amounts of several plants and a large amount of caffeine or a filler. There is no way to know from the label.

What has more evidence than any of them. Regular exercise, sleep, social connection, and addressing the actual stressor. A randomised trial of exercise for stress and anxiety has better evidence than any adaptogen trial, and it is free. Therapy — including CBT and stress-management programmes — has randomised evidence. Slow breathing at about 6 breaths per minute measurably affects autonomic measures within minutes.

The honest position. A person with a stressful period, sleeping badly and eating worse, does not have a deficiency of an adaptogen. The intervention is the sleep and the exercise, and a small amount of a well-tolerated plant is at best an adjunct.

What the studies found

Preparation

Ashwagandha

• 300-600 mg of a standardised root extract daily, in the trials
• Give it 8-12 weeks
• Case reports of liver injury exist. Stop if jaundice, dark urine or fatigue develops.
• Not in pregnancy or breastfeeding.
• Can be sedating; take in the evening if so

Rhodiola

• 200-400 mg of a standardised extract daily, usually in the morning
• Can be stimulating; avoid late in the day

Holy basil (tulsi)

• 1-2 g dried leaf as an infusion, or a standardised extract
• Small trials; generally gentle and pleasant

The interventions with more evidence

• Regular aerobic exercise — better evidence than any adaptogen
• Sleep — the relationship between sleep loss and stress reactivity is well established
• Slow breathing, about 6 breaths per minute, for 5-10 minutes: measurable autonomic effect
• CBT and stress-management training — randomised evidence
• Reducing caffeine, which amplifies the physical sensations of anxiety
• Social contact, which is protective and hard to supplement

Avoid the blend problem

• Buy a single-plant standardised product if you buy anything, so you know what you are taking and how much

Cautions and interactions

• Ashwagandha: case reports of liver injury. Avoid in liver disease; stop if symptoms develop.
• Ashwagandha is not for pregnancy or breastfeeding — it is traditionally used as an abortifacient.
• Rhodiola is stimulating — avoid late in the day, and be cautious with bipolar disorder.
• Adaptogen blends have no standard composition. A label does not tell you the doses.
• Ashwagandha can add to thyroid hormone effects and is used traditionally for thyroid; check with a clinician if on levothyroxine.

When this is not a self-care problem — get help

• Any suicidal thought or inability to function — clinical care, not an adaptogen.
• Jaundice, dark urine or unexplained fatigue on any of these — stop and get liver bloods checked.

Related

• Anxiety: kava, lavender and the herbs with trials
• Insomnia: what works before the herbs
• Low mood and depression
• Herbal liver injury, and the plant that ends the matter

Sources

1. Hormonal Modulation with Withania somnifera: Systematic Review and Meta-Analysis of Randomized-controlled Trials. Planta medica 2026; doi:10.1055/a-2802-8363 PubMed 41740946
2. Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis. Explore (New York, N.Y.) 2024; doi:10.1016/j.explore.2024.103062 PubMed 39348746
3. Plant Adaptogens-History and Future Perspectives. Nutrients 2021; doi:10.1007/s40242-012-2218-9 PubMed 34445021
4. A Systematic and Ethnobotanical Review of Ashwagandha's ( Withania Somnifera ) Teratogenic and Abortifacient Potentials. Phytotherapy research : PTR 2026; doi:10.1515/dmpt-2024-0056 PubMed 40887707
5. Clinical evidence for the adaptogenic effects of Withania somnifera and Rhodiola rosea - A systematic review with molecular interpretation of psychometric outcomes. Annals of agricultural and environmental medicine : AAEM 2026; doi:10.26444/aaem/213417 PubMed 41906501
6. Epigenetic modifications in drug-induced liver injury: A systematic review. British journal of clinical pharmacology 2025; doi:10.1111/bcp.70053 PubMed 40441699