Ashwagandha (Withania somnifera)


Adrenal fatigue, anxiety, and insomnia.

Mechanism of Action

The withanolides, a group of steroidal lactones, are credited with adrenal supportive effects.1 Steroidal compounds in plants are structurally similar to human steroids, and many are noted to have numerous physiological effects.

Animal studies suggest that ashwagandha is a γ-aminobutyric acid agonist, thereby having sedative effects on the CNS.2

Evidence-Based Research

Ashwagandha has been shown to improve cancer-related fatigue in one clinical outcome study investigating breast cancer patients.3

Ashwagandha reduces activation of the hypothalamic–pituitary–adrenal axis and cortisol release in a hyper state4,5; yet, it can increase cortisol when needed in cases of adrenal exhaustion,6 based on animal models of stress.

One double-blind, randomized, placebo-controlled trial evaluated the effects of ashwagandha on serum cortisol and reducing stress and anxiety. Three hundred milligrams of ashwagandha showed a significant reduction in stress, based on assessment scales in 2 months’ time relative to the placebo group, and the serum cortisol levels were substantially reduced.7

Safety in Pregnancy and Breastfeeding

Historical use considered safe, but no modern research has been done on pregnancy and lactation.

General Safety

No safety concerns based on traditional dose.


Dosage depends on whether ashwagandha is in a formula or by itself, but it is typically between 50 mg and 2 g a day of whole root.

Some manufacturers standardized to withanolide content, e.g., 1.5% withanolide content, but this varies from trial to trial, as an industry standard has yet to be established.



PLoS One. 2012;7(9):e44419. Differential activities of the two closely related withanolides, Withaferin A and Withanone: bioinformatics and experimental evidences. Vaishnavi K, Saxena N, Shah N, et al.

2 Am J Chin Med. 2013;41(5):1043–51. doi: 10.1142/S0192415X13500705. GABA-mimetic actions of Withania somnifera on substantia gelatinosa neurons of the trigeminal subnucleus caudalis in mice. Yin H, Cho DH, Park SJ, Han SK.

3 Integr Cancer Ther. 2013;12(4):312–22. Effect of Withania somnifera (Ashwagandha) on the development of chemotherapy-induced fatigue and quality of life in breast cancer patients. Biswal BM, Sulaiman SA, Ismail HC, Zakaria H, Musa KI.

4 Afr J Tradit Complement Altern Med. 2011;8(5 Suppl):208–13. An overview on ashwagandha: a Rasayana (rejuvenator) of Ayurveda. Singh N, Bhalla M, de Jager P, Gilca M.

5 Pharmacol Biochem Behav. 2003;75(3):547–55. Adaptogenic activity of Withania somnifera: an experimental study using a rat model of chronic stress. Bhattacharya SK, Muruganandam AV.

6 Phytother Res. 2000;14(2):122–5. Adrenocorticosterone alterations in male, albino mice treated with Trichopus zeylanicus, Withania somnifera and Panax ginseng preparations. Singh A, Saxena E, Bhutani KK.

7 Indian J Psychol Med. 2012;34(3):255–62. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Chandrasekhar K, Kapoor J, Anishetty S.