Ashwagandha (Withania somnifera) is one of the most important herbs in Ayurveda, where it has been used for centuries as a “rasayana”, a tonic for strength and resilience. It’s now one of the best-selling supplements in the US. Here’s what the evidence shows, and how to use it safely.
What people use it for
- Everyday stress and feeling “wired but tired”
- Sleep quality
- Energy, stamina and recovery from exercise
What studies show
- Stress and anxiety: several small clinical trials found that people taking ashwagandha root extract for 6 to 8 weeks reported lower stress scores and lower levels of the stress hormone cortisol than people taking a placebo.
- Sleep: some studies suggest modest improvements in how quickly people fall asleep and how well they sleep.
- Exercise: a few studies in active adults found small gains in strength and endurance.
Most studies were small and short, often lasting 8 to 12 weeks, so the results are promising but not conclusive. Ashwagandha isn’t a treatment for anxiety disorders, depression or insomnia. If those affect your daily life, talk to a doctor.
How to take it
- Studies typically used 250 to 600 mg of root extract a day. Follow the directions on your product.
- Take it with food to reduce stomach upset. Many people take it in the evening.
- Give it 4 to 8 weeks before judging the effect.
- Buy from a reputable brand, such as Himalaya Ashvagandha.
Side effects
- Common: upset stomach, diarrhoea, nausea and drowsiness
- Rare but serious: liver injury. Stop taking it and see a doctor straight away if you notice yellow skin or eyes, dark urine, pale stools, itching or pain in the upper right tummy.
Who should avoid it
- Pregnant women: high doses may cause miscarriage. Avoid it if pregnant or trying to conceive, and while breastfeeding.
- People with thyroid conditions: it may raise thyroid hormone levels
- People with autoimmune diseases such as rheumatoid arthritis, lupus or MS, as it may stimulate the immune system
- People with liver disease
- Anyone due to have surgery in the next 2 weeks, because it may add to the effects of anaesthesia
Drug interactions
Check with a doctor or pharmacist before taking ashwagandha if you take:
- Sedatives or sleeping tablets
- Thyroid medicine
- Diabetes or blood pressure medicines, as it may lower blood sugar and blood pressure
- Immune-suppressing medicines
Frequently asked questions
How long does ashwagandha take to work?
Most studies looked at results after 6 to 8 weeks of daily use.
Can I take ashwagandha every day?
Studies have used daily doses for up to about 3 months. Long-term safety isn’t well known, so talk to your doctor if you plan to take it for longer.
Should I take ashwagandha in the morning or at night?
Either works. If it makes you drowsy, take it in the evening.
Does ashwagandha help with weight loss?
Not directly. By helping with stress and sleep, it may support healthy habits. See our guide to Ayurvedic herbs for weight loss and sleep and weight loss.
This article is for general information only and isn’t a substitute for advice from a doctor or pharmacist. Supplements are not evaluated by the FDA to diagnose, treat, cure or prevent any disease.
