Ashwagandha Side Effects: What to Know First

For most healthy adults, ashwagandha does not cause harm when taken at the doses stated on the label and for limited periods. Reviews of clinical trials describe mostly mild to moderate effects, such as gastrointestinal discomfort, and no sign of relevant toxicity at the doses studied ¹. This does not mean it is harmless for everyone: there are groups who should avoid it, medicines it can interact with, and warning signs that mean you should stop.

The right question is not "does it cause harm?", but "does it cause harm to whom, at what dose and for how long?". That is what this article answers, with what studies show — and with what is still unknown.

What clinical trials say about safety

A randomised, double-blind, placebo-controlled trial specifically assessed the safety of ashwagandha root extract in 80 healthy adults (40 men and 40 women), who took 300 mg twice a day for 8 weeks. The authors analysed haematological parameters, serum biochemistry with assessment of hepatotoxicity and thyroid function, as well as adverse events and vital signs ².

A meta-analysis of 9 randomised trials, with 558 participants, assessed the effects of ashwagandha on stress and anxiety and recorded mild to moderate adverse events in four of the included studies ¹. Another meta-analysis, with 5 trials and 254 participants, focused on anxiety and insomnia, also found no serious safety problems at the durations studied ³.

A narrative review that gathered research from 1994 to the present noted that, despite daily consumption by millions of people in India, China and parts of the West, there are few case reports of side effects directly attributed to ashwagandha — which suggests that the administration of ashwagandha preparations may be safe ⁴.

Which side effects may appear

The effects most frequently described in trials are gastrointestinal and transient. In a critical review of preclinical and clinical evidence on adverse effects, the authors group the reported problems into gastrointestinal discomfort, immune hypersensitivity, liver toxicity and endocrine changes — mainly associated with prolonged or excessive use ⁵.

• Gastrointestinal discomfort — nausea, diarrhoea or stomach upset, more likely if you take it on an empty stomach.
• Drowsiness — some people feel sleepier; others report the opposite.
• Mild headache — uncommon and usually short-lived.
• Endocrine changes — the adverse effects review links the endocrine modulation of ashwagandha to cases of thyrotoxicosis and adrenal suppression, mainly with prolonged or excessive use ⁵.

If you feel any of these symptoms, try taking it with a meal. If they persist, reduce or stop for a few days and observe.

Dose: where the line between studied and excessive lies

There is no official maximum dose established for ashwagandha, which makes a simple answer difficult. What is known is that clinical trials typically use between 300 mg and 600 mg per day of root extract, for periods ranging from 8 to 24 weeks.

Some concrete examples: in a randomised trial in adults with stress, 150 mg and 300 mg per day of a sustained-release extract reduced Perceived Stress Scale scores over 60 days ⁶. In a 24-week trial in 100 adults, 300 mg twice a day were assessed for stress and body weight ⁷. In an 8-week study in 50 adults with mild cognitive impairment, 300 mg twice a day were used ⁸.

Stress Relief Gummies provide 300 mg of ashwagandha extract per serving of 2 gummies, plus 100 mg of L-theanine, 100 mg of GABA, 25 µg of vitamin D3 and 500 µg of vitamin B12. In other words, the dose per serving is within the most studied range, but remember: doses used in studies are not instructions for taking. Always follow the label.

With adaptogenic plants, prolonged or excessive use is associated with an increased likelihood of adverse effects ⁵.

Who should avoid it or speak to a professional first

There are groups in which caution should prevail. The adverse effects review identifies populations at increased risk of reactions and interactions, including people with thyroid, liver or autoimmune conditions ⁵.

• Pregnant and breastfeeding women — there are not enough safety data; the conservative recommendation is to avoid it. Talk to your doctor.
• People with thyroid disease — in a randomised, double-blind, placebo-controlled trial in 50 people with subclinical hypothyroidism (46 completed), 600 mg daily of root extract for 8 weeks significantly changed TSH, T3 and T4 levels compared with placebo ⁹. This shows real activity on the thyroid — anyone taking thyroid medication should talk to their doctor before use.
• People with autoimmune diseases — ashwagandha has immunomodulatory activity described in pharmacological reviews ¹⁰; in autoimmune conditions, it is prudent to seek professional guidance.
• People with liver disease — given the rare risk of liver toxicity described in the literature ⁵, it is prudent to avoid it or use it only with monitoring.
• Children and adolescents — there are not enough safety studies in this age group. Do not give ashwagandha to children.
• Before surgery — talk to your doctor about stopping supplementation before a planned procedure.

  If you are thinking of taking a break before planned surgery, the prudent recommendation is to stop ashwagandha at least two weeks before the procedure, because it can interfere with anaesthesia and blood pressure. Always confirm the timing with your doctor or anaesthetist.

Belonging to one of these groups does not necessarily mean you cannot take it, but it does mean you should not start without a conversation with a doctor or pharmacist.

Interactions with medicines: what the evidence suggests

The critical review of adverse effects highlights the need to identify interactions with prescription drugs for specific conditions ⁵. The areas needing most attention include:

• Thyroid medication — ashwagandha can change thyroid hormone levels, as shown in the trial in subclinical hypothyroidism ⁹.
• Thyroid medication — ashwagandha can change thyroid hormone levels, as shown in the trial in subclinical hypothyroidism ⁹.
• Diabetes medication — the plant has anti-diabetic activity described in pharmacological reviews ¹⁰; combined with antidiabetics, medical monitoring is prudent.
• Sedatives and anxiolytics — the effect on the central nervous system may be additive.

Do you take regular medication for a chronic condition? Do not start ashwagandha without talking to your doctor. It is a simple precaution that avoids serious problems.

Warning signs: when to stop and seek help

Most effects are mild, but there are signs you should not ignore. The adverse effects review describes cases of liver toxicity and immune hypersensitivity associated with ashwagandha ⁵. Stop taking it and seek a healthcare professional if you notice:

• Jaundice — yellow skin or eyes, dark urine, pale stools.
• Jaundice — yellow skin or eyes, dark urine, pale stools.
• Strong palpitations or irregular heartbeat.
• Dizziness or fainting from a drop in blood pressure.
• Allergic reaction — skin rash, itching, swelling of the face or difficulty breathing.

These signs are rare, but not impossible. If they appear, do not wait and see.

Ashwagandha in gummies: what changes in practice

The format does not change the intrinsic safety of the plant — as long as the dose is equivalent. What changes are practical aspects you should consider.

The format does not change the intrinsic safety of the plant — as long as the dose is equivalent. What changes are practical aspects you should consider.

Gummies contain sweeteners and texture agents. Stress Relief Gummies, for example, contain maltitol (a polyol) and pectin, and the label warns that excessive consumption may have a laxative effect. If you monitor your sugar intake or have a sensitivity to polyols, check the label.

Another point: gummies are easy to confuse with sweets, especially by children. Keep them out of reach of little ones. The label of these gummies states explicitly that they are not recommended for children, pregnant or breastfeeding women, or people with thyroid or autoimmune diseases. In case of liver disease, other diseases or taking medicines, you should consult a healthcare professional before use. It may cause drowsiness; if this occurs, do not drive or use machines.

If a child swallows several gummies by mistake, do not wait and see: contact your doctor, pharmacist or your country's poison information centre immediately.

What is still unknown

It is important to be honest about the gaps. A systematic review of 9 studies on cortisol in people with stress noted that none of the studies assessed the impact of cortisol reduction on adrenal function or long-term effects ¹¹. Most trials last weeks, not years. We do not know whether continuous use for years has cumulative effects, nor how ashwagandha interacts with all possible medicines — only with those that have been studied.

It is important to be honest about the gaps. A systematic review of 9 studies on cortisol in people with stress noted that none of the studies assessed the impact of cortisol reduction on adrenal function or long-term effects ¹¹. Most trials last weeks, not years. We do not know whether continuous use for years has cumulative effects, nor how ashwagandha interacts with all possible medicines — only with those that have been studied.

How to decide with common sense

Are you considering taking ashwagandha? Start by talking to your doctor or pharmacist, especially if you have any health condition or take medication. If you do not belong to any risk group and decide to go ahead, follow the label dose and do not increase it on your own initiative.

Are you considering taking ashwagandha? Start by talking to your doctor or pharmacist, especially if you have any health condition or take medication. If you do not belong to any risk group and decide to go ahead, follow the label dose and do not increase it on your own initiative.

Already taking it and it is going well? Keep following the instructions. Had mild effects? Try taking it with food. Had more serious effects? Stop and seek advice.

Frequently asked questions

Is ashwagandha bad for the liver?

At the doses studied and for limited periods, clinical trials show no relevant signs of liver toxicity. However, reviews of adverse effects describe rare cases of liver toxicity associated mainly with prolonged or excessive use. If you have liver disease or notice symptoms such as yellowing of the skin, stop and seek a doctor.

Can I take ashwagandha every day?

Clinical trials have assessed daily use for periods ranging from 8 to 24 weeks, with doses between 150 mg and 600 mg per day. There are no long-term safety data beyond those periods. If you intend to use it continuously, talk to a healthcare professional to assess your case.

Does ashwagandha interfere with thyroid medication?

Yes, it can. In a randomised trial in people with subclinical hypothyroidism, 600 mg daily for 8 weeks significantly changed TSH, T3 and T4 levels. If you take thyroid medication, do not start ashwagandha without talking to your doctor.

Who should not take ashwagandha?

Pregnant and breastfeeding women and children should not take it, due to a lack of safety data. People with thyroid disease, autoimmune diseases or liver disease should talk to a healthcare professional before use. The same applies to anyone taking regular medication.

Are ashwagandha gummies as safe as capsules?

The format does not change the safety of the plant as long as the dose is equivalent. Gummies have practical aspects to consider: they contain sweeteners such as polyols, which in excess may have a laxative effect, and they are easy for children to confuse with sweets, so they should be kept out of their reach.

Which side effects are most common?

The most frequent are gastrointestinal, such as nausea or stomach discomfort, as well as drowsiness and mild headache. In a meta-analysis of 9 trials, four reported mild to moderate adverse events. Taking it with a meal usually reduces discomfort.