Ashwagandha Side Effects: What You Need to Know

Ashwagandha has become a familiar name in the UK wellness scene, praised for its ability to help the body adapt to stress, improve energy, and support mental balance. While it’s widely considered safe for most healthy adults, it’s still a potent herbal extract, and understanding its possible side effects is important. Like any supplement, ashwagandha can affect people differently depending on their health, lifestyle, and dosage. Knowing what to expect helps you make an informed and confident choice about whether it’s right for you.

Want to learn more about how ashwagandha works and what to expect? Visit our Ashwagandha Guidance Hub, where we answer the most common questions and explore the science behind this ancient herb.

A Closer Look at Ashwagandha

Ashwagandha, scientifically known as Withania somnifera, is a traditional Ayurvedic herb often used to enhance resilience and reduce stress. It’s classified as an adaptogen, meaning it helps the body maintain balance in the face of physical, mental, or emotional strain. Most modern supplements use a standardised extract from the root, which contains compounds known as withanolides. These are thought to be responsible for the herb’s stress-regulating and antioxidant effects.

While its benefits are well-documented in traditional use and growing research, ashwagandha still interacts with the body’s endocrine, immune, and nervous systems. Because of this, it’s essential to take it thoughtfully, especially if you have specific medical conditions or take medication.

Commonly Reported Side Effects

Most people tolerate ashwagandha well, particularly when using moderate doses of standardised extract. However, a small number of users report mild side effects, especially during the first few weeks of use as the body adjusts.

Some of the more common side effects include mild digestive discomfort such as nausea, upset stomach, or loose stools. These effects often occur if ashwagandha is taken on an empty stomach, so it’s usually best to take it with food.

Other users occasionally experience slight drowsiness or a calming effect, which may be more noticeable if the supplement is taken in higher doses or near bedtime. This is part of the herb’s relaxing quality, but it can be unwanted if taken before activities that require alertness.

Some people may also notice temporary changes in appetite or mood as their body adapts. These symptoms tend to settle as balance is restored.

Potential Hormonal Effects

Ashwagandha influences several hormones, including cortisol, testosterone, and thyroid hormones. While these effects can be beneficial in people with imbalances, they may cause mild disruptions in sensitive individuals.

For example, ashwagandha is known to reduce cortisol levels, which can support relaxation and recovery. However, if cortisol levels become too low, it may lead to fatigue or reduced alertness. This is rare but worth monitoring if you already have low blood pressure or adrenal function.

In men, ashwagandha may slightly boost testosterone, which can enhance energy and strength. Women may also benefit from improved hormone balance, but those with certain hormone-sensitive conditions such as polycystic ovary syndrome (PCOS) or endometriosis should seek medical advice before use.

Ashwagandha’s effect on the thyroid may also be significant. Some studies suggest it can increase thyroid hormone production, which might be helpful in mild hypothyroidism but problematic in those with hyperthyroidism. People taking thyroid medication should therefore consult their GP before starting supplementation.

Allergic or Sensitivity Reactions

Although rare, allergic reactions to ashwagandha can occur. These might include itching, rash, or swelling. If you experience any of these symptoms, stop taking the supplement immediately and seek medical advice.

Some individuals may also be sensitive to specific ingredients in ashwagandha capsules or gummies, such as binders, flavourings, or sweeteners. Checking labels carefully and choosing products with minimal additives can help prevent unnecessary reactions.

Ashwagandha and the Digestive System

Ashwagandha can affect digestion in several ways. For some, it soothes an overactive stress response and reduces gut discomfort, while for others it may cause mild nausea, bloating, or diarrhoea. These effects are typically linked to taking too high a dose or using low-quality raw powders that are harder to digest.

Using standardised root extract, starting with smaller doses, and taking it with food can help reduce digestive discomfort. For those who experience ongoing issues, switching to gummies or a different brand may make it easier on the stomach.

Interactions with Medications

Because ashwagandha influences hormones and the nervous system, it can interact with certain medications. Those taking thyroid medication, sedatives, anti-anxiety drugs, antidepressants, or medications for autoimmune conditions should consult their GP before using ashwagandha.

It may enhance the effects of sedatives or thyroid hormones, and in some cases, it can reduce the effectiveness of immunosuppressive drugs. While these interactions are uncommon, it’s safest to discuss any supplement use with your healthcare provider if you’re on prescription medication.

Not Recommended During Pregnancy or Breastfeeding

Although ashwagandha has been used in traditional medicine for centuries, it’s not recommended during pregnancy or breastfeeding due to limited research on safety in these stages. Some animal studies suggest that high doses may stimulate uterine activity, so it’s best to avoid it entirely during pregnancy unless advised by a qualified practitioner.

Breastfeeding women should also exercise caution, as the active compounds may pass into breast milk, and their effects on infants have not been established.

Ashwagandha and Autoimmune Conditions

Ashwagandha may stimulate the immune system, which is beneficial for general wellbeing but could potentially worsen autoimmune conditions such as lupus, rheumatoid arthritis, or multiple sclerosis. People with these conditions should speak with a medical professional before use, as boosting immune activity might interfere with certain treatments.

Signs You May Be Taking Too Much

Taking more ashwagandha than recommended does not necessarily increase its benefits and may raise the risk of side effects. Signs of excessive intake can include nausea, dizziness, headaches, or an unusually sedated feeling.

Most research suggests that daily doses of 300 to 600 mg of standardised extract are both safe and effective for adults. Higher doses should only be taken under professional guidance. Consistency is more important than quantity, as ashwagandha works gradually to support balance rather than offering immediate results.

Long-Term Safety

Clinical studies have generally found ashwagandha to be safe for use over several months, though long-term data beyond six months is limited. For this reason, some experts recommend taking short breaks between cycles of use to allow the body to reset. This approach can help maintain effectiveness and minimise the chance of tolerance or dependency.

If you decide to take breaks, two to four weeks off every few months is a sensible rhythm. During this time, you can assess whether the supplement’s benefits continue and whether your energy or stress levels remain steady without it.

How to Minimise Side Effects

To reduce the likelihood of unwanted reactions, start with a low dose and increase gradually if needed. Always take ashwagandha with food, avoid mixing it with alcohol or sedatives, and choose high-quality products that list their extract type and concentration.

If you are using other adaptogens or herbal supplements, monitor your response carefully, as combining multiple stress-modulating herbs can amplify effects. Staying hydrated, maintaining a balanced diet, and getting adequate rest all help your body adjust more smoothly to ashwagandha’s influence.

Who Should Avoid Ashwagandha

Ashwagandha may not be suitable for everyone. It should generally be avoided by:

• Pregnant or breastfeeding women
• People with hyperthyroidism or on thyroid medication
• Those with autoimmune diseases unless advised by a doctor
• Individuals taking sedatives, antidepressants, or immunosuppressants
• Anyone allergic to plants in the nightshade family, which includes ashwagandha

If any symptoms of discomfort persist beyond a few days or worsen over time, it’s best to stop taking the supplement and consult your GP.

Conclusion

Ashwagandha is a well-studied herb with impressive potential for supporting stress, energy, and balance. For most healthy adults, it is safe and well-tolerated when used at appropriate doses. However, like all natural supplements, it’s important to use it responsibly and with awareness of your body’s responses. Starting slowly, taking it with food, and choosing reputable, high-quality products can help you enjoy its benefits while minimising side effects.