Ashwagandha is a herb from Ayurvedic medicine, taken mainly for stress, anxiety and sleep. It has more supporting evidence than most herbal supplements — though studies are generally small and short. It also carries real cautions, including reports of liver injury and effects on the thyroid.
What is Ashwagandha?
Ashwagandha is the root of Withania somnifera, a shrub used in Ayurvedic medicine for centuries. It is also called Indian ginseng or winter cherry, though it is unrelated to true ginseng.
Its active compounds are withanolides, a group of steroidal lactones. The withanolide content is what determines potency, and it varies enormously between products — which is why two ashwagandha supplements can behave quite differently.
Ashwagandha is classed as an “adaptogen” — a term for substances said to help the body resist stress. That word deserves a note of caution: it is a traditional and marketing category rather than a precise pharmacological one, and it is used loosely across the supplement industry.
What the research actually suggests is that ashwagandha affects the hypothalamic-pituitary-adrenal axis — the system governing the stress response — and appears to lower cortisol. Several trials have found reductions in perceived stress and anxiety scores alongside falls in cortisol.
Ashwagandha has better evidence than most herbal supplements, which is worth acknowledging honestly. It also has real limitations: most trials are small, short (typically 6 to 12 weeks), and a number are funded by supplement manufacturers. Standardised extracts used in studies — such as KSM-66 and Sensoril — are not necessarily what is in a given product.
Root extract and leaf extract are not the same. Traditional use is of the root; some modern products include leaf, which has a different withanolide profile. Check the label.
What is Ashwagandha commonly used for?
- Stress and anxiety — the most common reason, and where evidence is strongest.
- Sleep, particularly difficulty falling asleep related to stress. The species name somnifera means “sleep-inducing”.
- Fatigue and low energy.
- Athletic performance and muscle strength, where some trials suggest modest benefit alongside resistance training.
- Testosterone and male fertility, where a few small studies show effects — though the evidence is limited.
- Thyroid function, where it may raise thyroid hormone levels — relevant as both a claimed benefit and a genuine risk.
- Cognitive function and memory, with limited evidence.
- Blood sugar and cholesterol, with preliminary evidence.
- Menopausal symptoms, and general wellbeing.
Set realistic expectations. Where benefits appear, they are modest and typically emerge over four to twelve weeks of consistent use. Ashwagandha is not a treatment for a diagnosed anxiety disorder or depression, and it should not replace treatment for one.
If stress or anxiety is affecting your work, relationships or daily functioning, that warrants proper assessment. Psychological therapy and, where appropriate, prescribed treatment have far better evidence than any supplement.
Who commonly looks for Ashwagandha and why
- People under sustained stress, or with work-related burnout.
- People with anxiety, often looking for a non-prescription option.
- People with difficulty sleeping.
- Gym-goers and athletes, for strength, recovery and testosterone.
- Men concerned about testosterone or fertility.
- People with fatigue, hoping for an energy benefit.
- People interested in Ayurvedic or traditional medicine.
- People wanting to avoid prescription anxiety medicines, particularly given the dependence risk with benzodiazepines such as diazepam.
- Women around menopause.
What to check on the label before taking Ashwagandha
- Whether it is root extract or includes leaf. Traditional use is root.
- The withanolide percentage, which determines potency. Without it, the dose figure means little.
- Whether it is a standardised extract such as KSM-66 or Sensoril, as used in trials.
- The dose per serving. Trials commonly used 300–600 mg of standardised extract daily.
- Other ingredients, particularly in “stress” or “sleep” blends — some include melatonin, other herbs, or stimulants.
- Certification or testing, given that heavy metal contamination has been reported in some Ayurvedic products. Look for third-party testing.
- The expiry date and storage.
Safety, interactions and when to seek professional advice
Ashwagandha is generally well tolerated at usual doses. Common effects are stomach upset, nausea, diarrhoea and drowsiness.
Three cautions deserve particular attention:
Liver injury. Cases of ashwagandha-associated liver damage have been reported internationally, some serious, typically appearing within a few months of starting. Stop and seek medical advice if you develop yellowing of the eyes or skin, dark urine, pale stools, persistent nausea, marked fatigue or itching.
Thyroid effects. Ashwagandha can increase thyroid hormone levels. This is sometimes marketed as a benefit for an underactive thyroid, but it can also cause or worsen an overactive thyroid, and it can interfere with thyroid medicine dosing. If you have any thyroid condition or take levothyroxine, speak to your doctor first.
Sedation and additive effects. It can add to the effect of sedatives, alcohol, and medicines for anxiety or sleep.
Do not take ashwagandha if you are pregnant. It has traditionally been used to induce abortion, and it is contraindicated in pregnancy. Avoid it while breastfeeding too.
Speak to a doctor or pharmacist before taking it if you:
- Have any thyroid condition, or take thyroid medicine.
- Have liver disease, or a history of liver problems.
- Have an autoimmune condition — rheumatoid arthritis, lupus, multiple sclerosis, type 1 diabetes. Ashwagandha may stimulate immune activity.
- Take immunosuppressants, including after a transplant.
- Take sedatives, benzodiazepines, sleeping tablets or antidepressants.
- Take diabetes medicines, as it may lower blood sugar.
- Take blood pressure medicines, as it may lower blood pressure.
- Have surgery planned — stop it at least two weeks beforehand.
- Have a hormone-sensitive condition, such as prostate cancer.
- Are giving it to a child.
- Have a nightshade allergy, as Withania is in the nightshade family.
See a doctor rather than self-treating if you have:
- Anxiety or low mood affecting daily life, or thoughts of self-harm. Seek help promptly.
- Persistent insomnia beyond a few weeks.
- Persistent fatigue, which has many treatable causes including anaemia, thyroid disease, diabetes and sleep apnoea.
- Palpitations, weight loss, tremor or heat intolerance — possible overactive thyroid, which ashwagandha could worsen.
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Frequently asked questions
What is ashwagandha used for? Mainly stress, anxiety and sleep, and also fatigue, athletic performance and testosterone. Evidence is strongest for stress and anxiety.
What is ashwagandha used for in women? The same core uses — stress, anxiety and sleep — plus menopausal symptoms. It must not be taken in pregnancy, where it is contraindicated.
Does it actually work? It has better evidence than most herbal supplements for stress and anxiety, but trials are small, short and often industry-funded. Effects are modest.
How long before I notice a difference? Trials typically ran four to twelve weeks. It is not a fast-acting remedy.
Is it safe? Generally well tolerated, but there are reports of liver injury, it can raise thyroid hormone levels, and it is contraindicated in pregnancy.
Can I take it with my thyroid medicine? Speak to your doctor first. Ashwagandha can raise thyroid hormone levels and interfere with dosing.
Does it raise testosterone? A few small studies suggest an effect in men, but the evidence is limited and should not be over-interpreted.
Can I take it with anxiety medication? Ask your doctor. It can add to the effect of sedatives and antidepressants, and it does not replace treatment for a diagnosed condition.