Each review contains information about the ingredient’s clinical applications, formulations, dosing & administration, adverse effects, and pharmacokinetics. Learn more about our critical appraisal research or contact us for initial guidance and more information.

Withania somnifera

Withania somnifera (WS) is also commonly known as ashwagandha, “Indian Winter cherry” or “Indian Ginseng”. Its root, leaves, and seeds have been historically used as a tonic to assist with stress, neuroprotection, arthritis, pain, and inflammation. It is one of the most highly regarded ayurvedic medicines. (20) Withania somnifera extract contains numerous phytochemicals, such as alkaloids, flavonoids, steroidal lactones, saponins, neurotransmitters, essential and nonessential fatty acids, ergostane, and gamma amino butyric acid, which contribute to its many therapeutic effects. (3)

Not be confused with: Withania coagulans

Main uses

Anxiety and stress
Cognition in neurological disorders
Fertility
Joint pain and muscular performance

Formulations

Form	Bioavailability and safety
Non-proprietary standardized extracts	Withanolides absorbed rapidly, withaferin A had 1.5x higher bioavailability than withanolide A in mice (17) High dose of 2000mg/kg of body weight of a standardized extract containing <3% of Withaferin A did not produce adverse effects or toxicity in rats (16)
KSM-66® (root extract containing a 5% concentration of withanolides)	No data on bioavailability currently available Has been shown to be safe for 12 weeks (1)
Sensoril® (root and leaf extract containing a minimum of 8% concentration of withanolides) (5)	No data on bioavailability currently available Has been shown to be safe for 12 weeks (18)(23)
Shoden® (root and leaf extract standardized to 35% withanolide glycosides) (14)	No data on bioavailability currently available Has been shown to be safe for 8 weeks (14)

Dosing & administration

Bipolar disorder
General outcomes from A-level evidence	Actualmente no hay datos disponibles.
Dosing & administration	500 mg (as Sensoril® standardized extract) per day for 8 weeks
Resultados	↑ auditory-verbal working memory, a measure of reaction time, & a measure of social cognition in bipolar disorder (5)
Class of evidence	B

Chronic stress
General outcomes from A-level evidence	No data currently available.
Dosing & administration	600 mg (as KSM-66® standardized extract) per day for 6 weeks
Outcomes	↑ resistance to stress ↓ serum cortisol, body weight (4)(8)
Class of evidence	B
Dosing & administration	125 mg (as Sensoril® standardized extract) per day for 8 weeks
Outcomes	↓ stress & anxiety score (62%), serum cortisol (14.5%), CRP (31.6%), pulse rate (6.0%), systolic blood pressure (1.6%), diastolic blood pressure (5.6%), & VLDL-C (8.9%) ↑ serum DHEAS (13.2%) & Hgb (6.3%) (2)
Class of evidence	B
Dosing & administration	125 mg (as Sensoril® standardized extract) per day for 8 weeks
Outcomes	↓ stress & anxiety score, serum cortisol (24.2%), CRP (36.6%), FBG (4.7%), total cholesterol (7.0%), TGs (9.5%), LDL-C (9.0%), VLDL-C (16.6%), pulse rate (8.2%), systolic blood pressure (3.4%), diastolic blood pressure (5.0%) ↑ serum DHEAS (32.2%) & Hgb (4.0%) (2)
Class of evidence	B
Dosing & administration	250 mg (as Sensoril® standardized extract) twice per day for 8 weeks
Outcomes	↓ stress & anxiety score, serum cortisol (30.5%) & CRP (35.2%), FBG (6.1%), total cholesterol (13.1%), TGs (11.7%), LDL-C (17.4%), VLDL-C (23.9%), pulse rate (6.6%), systolic blood pressure (3.3%), diastolic blood pressure (6.4%) ↑ serum DHEAS (32.5%), HDL-C (17.3%), & Hgb (9.1%) (2)
Class of evidence	B

Hypothyroidism (subclinical)
General outcomes from A-level evidence	No data currently available.
Dosing & administration	600 mg (as ashwagandha root extract) per day for 8 weeks
Outcomes	Normalized TSH, T3, T4 (19)
Class of evidence	B

Infertility
General outcomes from A-level evidence	No data currently available.
Dosing & administration	600 mg (as KSM-66® standardized extract) per day for 8 weeks
Outcomes	↑ arousal, lubrication, orgasm, satisfaction, FSDS score, number of successful sexual encounters (12)
Class of evidence	B
Dosing & administration	675 mg (as KSM-66® standardized extract) per day for 90 days
Outcomes	↑ serum testosterone & luteinizing hormone levels, sperm concentration, motility, & semen volume (1)
Class of evidence	C

Knee joint pain
General outcomes from A-level evidence	No data currently available.
Dosing & administration	125 mg or 250 mg (as Sensoril® standardized extract) twice per day for 12 weeks
Outcomes	↓ mean mWOMAC & KSI, VAS scores for pain, stiffness & disability (18)
Class of evidence	B

Memory loss and cognitive function
General outcomes from A-level evidence	No data currently available.
Dosing & administration	600 mg (as ashwagandha root extract) per day for 8 weeks
Outcomes	↑ immediate & general memory, executive function, attention & information processing speed (7)
Class of evidence	B

Obsessive compulsive disorder (OCD)
General outcomes from A-level evidence	No data currently available.
Dosing & administration	120 mg (as ashwagandha root extract) per day for 7 weeks
Outcomes	↓ Yale-Brown Obsessive Compulsive Scale (13)
Class of evidence	C

Schizophrenia
General outcomes from A-level evidence	No data currently available.
Dosing & administration	500 mg (as Sensoril® standardized extract) twice per day for 12 weeks
Outcomes	↑ improvements on PANSS negative, general, & total symptoms, PSS scores (6)
Class of evidence	B

Strength training
General outcomes from A-level evidence	No data currently available.
Dosing & administration	500 mg (as KSM-66® standardized extract) per day for 8 weeks
Outcomes	↑ muscle mass, strength, testosterone ↓ muscle damage, fat mass (22)
Class of evidence	B
Dosing & administration	500 mg (as Sensoril® standardized extract) per day for 8 weeks
Outcomes	↑ muscle mass and strength (23)
Class of evidence	C

Adverse effects

Ashwagandha is generally reported to be safe, with only minor adverse effects of gastrointestinal distress, diarrhea, nausea, and vomiting associated with large doses. Rare cases of hepatotoxicity have been reported. (15)

Pharmacokinetics

Absorption

Withaferin-A and withanolide A have been shown to be rapidly absorbed in mice. (10)
Oral bioavailability of witherfarin A has shown to be ~32% in rats but can easily pass through epithelial cells as shown in vitro. (9)

Distribution

From highest to lowest concentrations, withaferin A has been shown to have tissue distribution in the stomach, heart, lung, kidney, small intestine, and spleen in rats. (21)

Metabolism

Intestinal and liver first-pass metabolism may contribute to low bioavailability of witherfarin A as shown in rats and in vitro. (9)

Excretion

No data currently available