Ashwagandha Side Effects | Safety & What to Know

Ashwagandha (Withania somnifera) is one of the most widely used adaptogens in the world, with a history stretching back more than 3,000 years in Ayurvedic medicine. Research suggests it may support the stress response, promote calm, and help maintain cognitive performance — but like any bioactive botanical, it comes with safety considerations worth understanding before you start.

Despite its widespread use, Ashwagandha is considered generally safe and without major adverse effects in clinical trial settings. Among the studies included in a major stress and anxiety meta-analysis, four reported only mild to moderate adverse events. However, reports of rarer but more serious Ashwagandha side effects — particularly involving the liver and the endocrine system — have emerged in recent years and deserve careful attention.

This guide walks through what the research actually says about Ashwagandha side effects, who should exercise caution, and how this adaptogenic herb interacts with medications. If you have specific health concerns or take prescription medications, our naturopath is available for a free consultation to help you evaluate whether Ashwagandha is appropriate for you.

General Tolerability

In clinical trials, Ashwagandha has generally been well tolerated. There have been no reports of serum enzyme elevations occurring during therapy in controlled trial settings, and no mention of serious adverse events or hepatotoxicity within those studies. A sleep meta-analysis analyzing five randomized controlled trials with 400 participants also reported no serious side effects.

Liver Toxicity (Hepatotoxicity)

Although rare, there have been a number of cases linking liver injury to Ashwagandha supplements. The NIH classifies Ashwagandha as a liver toxicity grade B, which means it is likely a cause of clinically apparent liver injury. Importantly, supplement liver toxicity data is likely highly underreported because there is no obligation to report adverse events — hepatologists are only seeing a small proportion of the millions of people taking Ashwagandha.

A molecular study suggested an important role for the withanolide withanone in Ashwagandha-induced liver injury. Withanone consists of electrophilic functional groups associated with adverse drug reactions, referred to as toxicophores, responsible for toxicity. Metabolic transformation via cytochrome P450 enzymes can form reactive intermediates, leading to oxidative stress and hepatotoxicity.

A USP safety review noted the long history of apparently safe usage in traditional Ayurvedic practices, but cautioned that history of use may not be adequately reported, the scope of adverse events may not be observable, and there can be great variability in botanical raw material.

Gastrointestinal Side Effects

Gastrointestinal side effects have been reported, particularly with prolonged or excessive usage. These may include stomach discomfort and related digestive complaints.

Endocrine Disruption and HPA Axis Suppression

The endocrine-modulating activity of Ashwagandha has been implicated in thyrotoxicosis and adrenal suppression. A case report described a 55-year-old postmenopausal woman who presented with Cushingoid features and progressive weight gain over a year. Evaluation revealed low basal cortisol levels and a suboptimal response to the ACTH stimulation test, indicative of adrenal insufficiency. Further investigation uncovered her consistent use of approximately 950 mg of Ashwagandha daily for over a year.

Research also demonstrates that active substances from Ashwagandha can increase the secretion of triiodothyronine (T3) and thyroxine (T4) by the thyroid gland and decrease the level of thyroid-stimulating hormone (TSH). In 50 adults with subclinical hypothyroidism, KSM-66 at 600 mg/day for 8 weeks decreased TSH and increased T3 and T4 versus placebo. These effects suggest Ashwagandha may interact with thyroid medications and affect thyroid hormones even in people without thyroid disease.

Immune Hypersensitivity

Immune hypersensitivity reactions have been reported, particularly with prolonged or excessive usage.

Understanding Ashwagandha side effects also means knowing who should not take it at all. Based on the available evidence, the following populations should exercise caution or avoid Ashwagandha entirely:

• Pregnant and breastfeeding women: Ashwagandha should be avoided during pregnancy and should not be used while breastfeeding.
• People scheduled for surgery: Ashwagandha is not recommended for people who are about to have surgery.
• Those with autoimmune disorders: Due to its immune-modulating properties, Ashwagandha is not recommended for people with autoimmune conditions.
• Those with thyroid disorders: Because Ashwagandha can alter thyroid hormone levels (increasing T3 and T4 while decreasing TSH), it is not recommended for people with thyroid disorders.
• Men with hormone-sensitive prostate cancer: Because Ashwagandha may increase testosterone levels, people with hormone-sensitive prostate cancer should avoid its use.

If you fall into any of these categories or are unsure whether Ashwagandha is right for your situation, we encourage you to take advantage of our free naturopathic consultation.

One of the most important Ashwagandha side effects to be aware of involves its potential to interact with medications. There is evidence that Ashwagandha might interact with several categories of drugs:

• Diabetes medications: Ashwagandha may influence blood sugar levels, potentially altering the effectiveness of diabetes drugs.
• Blood pressure medications: Some clinical evidence suggests Ashwagandha may reduce blood pressure in stress-related contexts, which could compound the effects of antihypertensive medications.
• Immunosuppressants: Because Ashwagandha has immune-modulating properties, it may decrease the effectiveness of immunosuppressant medications.
• Sedatives: Ashwagandha exhibits GABAergic activity and has sedative and hypnotic effects, which may compound the effects of sedative drugs.
• Anticonvulsants (anti-seizure medications): Potential interactions have been noted with anticonvulsant drugs.
• Thyroid hormone medications: Given Ashwagandha's documented effects on T3, T4, and TSH levels, it may interfere with thyroid hormone replacement therapy.

Subsequent studies should also emphasize pharmacogenomic responsiveness given potential variability in cytochrome P450 (CYP)-mediated metabolism and genetic differences in stress-response pathways. If you take any prescription medications, discussing Ashwagandha with a knowledgeable practitioner is important — our naturopath can help you evaluate potential interactions during a free consultation.

While the clinical evidence for Ashwagandha's benefits in areas like stress, anxiety, and physical performance is growing, the safety picture has notable gaps. Most clinical studies last only 2–3 months, and long-term safety beyond six months is less defined.

The existing research base also has methodological shortcomings, including heterogeneity in the preparation of extracts, small sample sizes, variability in endpoints, and possible funding-related biases. The strength of findings is further hampered by the small sample sizes used and short treatment durations, with no study greater than 8 weeks in some meta-analyses. Divergent Ashwagandha extracts with varying treatment doses were also used across studies.

Many clinical trials have looked at Ashwagandha for a variety of health conditions. However, many of the studies have had small sample sizes and have used a variety of Ashwagandha preparations — making it harder to draw definitive conclusions about long-term safety across all forms and dosages.

This formula combines four well-known adaptogens — Ashwagandha root extract, Bacopa leaf extract, Rhodiola root extract, and Schisandra fruit — with Black pepper fruit extract for bioavailability support. It's formulated as a vegan-friendly VegCap and is designed for adults looking to support their body's natural ability to adapt to environmental stressors.

Based on the ingredients and their documented areas of support, this formula may be particularly relevant for:

• Adults experiencing everyday stress who want to support their stress response and HPA axis function
• Those seeking to support mental well-being, cognitive performance, and a sharper mind-body connection
• Active individuals looking to support physical performance, endurance, and muscle strength
• Aging adults interested in supporting cognitive performance
• Anyone wanting adaptogenic support for the immune and nervous systems

This formula is vegan and requires no membership or autoship to purchase.

Take 2 VegCaps daily.

Each serving of 2 VegCaps provides 600 mg of Ashwagandha root extract, 395 mg of Bacopa leaf extract, 395 mg of Black pepper fruit extract, 395 mg of Schisandra fruit, and 395 mg of Rhodiola root extract.

Most clinical studies on Ashwagandha and its companion adaptogens have lasted 2–3 months. Effects on cognitive function from Bacopa are typically observed after 12 weeks of consistent supplementation. If you have questions about whether this blend is appropriate for your needs, our naturopath is available for a free consultation.