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Last updated: Aug 31, 2021
5 min read

6 possible ashwagandha side effects

Mike Bohl, MD, MPH, ALMlinnea zielinski

Medically Reviewed by Mike Bohl, MD, MPH, ALM

Written by Linnea Zielinski


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Wouldn’t it be nice to take a supplement that could help you deal with the physical and mental stressors you deal with every day? That’s what many claim ashwagandha can do. This root is considered an adaptogen—a family of medicinal plants popular in alternative medicine for their potential to help the body adapt to stress. 

For centuries, traditional Indian, African, and Ayurvedic medicine have been using ashwagandha—also known as Withania somnifera, Indian ginseng, or winter cherry. But more stress is the last thing you want from an herbal remedy for stress, so it’s worth getting familiar with ashwagandha’s potential side effects.

Even if you’re buying from the best sources, everyone reacts to supplements differently. Though most research shows that many people handle ashwagandha without a problem, that might not be the case for you. That’s why you should know about the potential ashwagandha side effects before beginning supplementation and also discuss it with your healthcare provider.

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1. May increase thyroid function

This may sound like welcome news for some, especially those suffering from conditions characterized by low thyroid function, such as hypothyroidism and Hashimoto’s thyroiditis. Still, it can be dangerous for people with already elevated thyroid function or hyperthyroidism. 

One study looked at people with subclinical hypothyroidism (meaning thyroid levels that weren’t low enough for a diagnosis of hypothyroidism). In those who took ashwagandha root extract, the two main thyroid hormones, triiodothyronine (T3) and thyroxine (T4), returned to normal levels. Researchers believe this effect may happen due to ashwagandha’s cortisol-lowering effect, but more work must be done to confirm that (Sharma, 2018). 

This study sparks hope that Withania somnifera may prove helpful in treating people with thyroid function that isn’t low enough to meet the blood level cutoffs of true hypothyroidism but can still cause lethargy, weight gain, and hair loss. 

But people whose thyroids are already working overtime are treated with medicine that lowers their thyroid hormone output, so this side effect of ashwagandha could potentially be dangerous for them or interact poorly with their medicine. Left untreated, rising thyroid hormone levels in someone with hyperthyroidism can lead to a serious condition called thyrotoxicosis that can lead to many conditions, including heart failure.

2. Can decrease blood pressure

Although some people would appreciate a supplement that lowers blood pressure, this side effect of ashwagandha can be dangerous for others. Many people with hypertension, or high blood pressure, are on a prescription medication monitored by their primary care physician to lower their blood pressure. Taking ashwagandha along with these drugs may cause your blood pressure to drop further (MedlinePlus, 2020). That’s why you should always seek out medical advice before adding something new to your regimen.

3. May irritate GI tract

Animal studies have suggested that ashwagandha may protect against stress-induced gastric ulcers (Bhatnagar, 2005). However, these results don’t necessarily translate to humans. In fact, our gastrointestinal (GI) tracts can also get too much ashwagandha. Large doses of this herb may lead to an upset stomach, vomiting, or diarrhea (MedlinePlus, 2020). More human studies are needed in this area.

4. May induce miscarriages

First things first: pregnant people should always seek medical advice from a healthcare professional before starting any supplement, no matter how benign it seems. While pregnancy can be both joyous and stressful, ashwagandha isn’t the answer for stress relief in this case. Despite its many benefits, ashwagandha contains compounds that may cause miscarriage (MedlinePlus, 2020). If you’re feeling stressed, talk to your healthcare provider about potential treatment plans.

5. May decrease blood sugar

More research does need to be done in this area, but several animal studies suggest that ashwagandha may lower blood sugar levels. But clinical trials in humans are limited for now (Durg, 2020). If you already have low blood sugar levels or are taking diabetes medications, using ashwagandha may cause your glucose levels to drop dangerously low.

6. May boost immune activity

Having a robust immune system that’s working hard for you is good, right? Not always. People with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, or multiple sclerosis can potentially worsen their symptoms by taking ashwagandha. Autoimmune diseases are characterized by the body attacking itself, so the more immune function, the harder it will fight. Since ashwagandha may boost your immune response, people with these health conditions should avoid this herbal supplement (MedlinePlus, 2020).

Benefits of ashwagandha

It’s worth noting that ashwagandha is generally well-tolerated, and its potential health benefits are wide-ranging. Many of its adaptogenic health benefits come from withanolides, steroids that occur naturally in nightshades. 

Ashwagandha extract is touted to have anxiolytic (anti-anxiety) and anti-inflammatory properties. It may also potentially boost testosterone levels and improve male infertility in certain populations. Some studies also suggest that it can lower cortisol (stress hormone) levels in people with chronic stress (Mandlik Ingawale, 2021). 

When to see a healthcare provider

Unfortunately, there’s a low barrier to entry for some herbal supplements looking to hit the market—and quality may be the cost. It seems benign enough to buy any supplement, especially if it has good reviews from other buyers, but it can be quite dangerous. 

Ashwagandha specifically isn’t free from incidents of poor quality products harming people, either. Several cases of liver injury have been reported about ashwagandha. When they investigated the products in question, it turned out that many contained contaminants (NIDDK, 2019). Avoid these safety concerns by buying from a company you can trust.

Seek medical advice from your healthcare provider if you are experiencing any of the above side effects, especially if they are getting worse or do not improve after stopping ashwagandha. Speak with your healthcare provider before starting a new supplement like ashwagandha.

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  1. Andallu, B., & Radhika, B. (2000). Hypoglycemic, diuretic and hypocholesterolemic effect of winter cherry (Withania somnifera, Dunal) root. Indian Journal of Experimental Biology, 38(6), 607–609. Retrieved from
  2. Bhatnagar, M., Sisodia, S.S., & Bhatnagar, R. (2005). Antiulcer and antioxidant activity of Asparagus racemosus Willd and Withania somnifera Dunal in rats. Annals of the New York Academy of Sciences, 1056, 261–278. doi: 10.1196/annals.1352.027. Retrieved from
  3. Durg, S., Bavage, S., & Shivaram, S.B. (2020). Withania somnifera (Indian ginseng) in diabetes mellitus: A systematic review and meta-analysis of scientific evidence from experimental research to clinical application. Phytotherapy Research: PTR, 34(5), 1041–1059. doi: 10.1002/ptr.6589. Retrieved from
  4. Mandlik Ingawale, D.S., & Namdeo, A.G. (2021). Pharmacological evaluation of Ashwagandha highlighting its healthcare claims, safety, and toxicity aspects. Journal of Dietary Supplements, 18(2), 183–226. doi: 10.1080/19390211.2020.1741484. Retrieved from
  5. MedLine Plus. (2020). Ashwagandha. Retrieved Aug 30, 2021 from
  6. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2019, May). Ashwagandha. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]; 2012-. Retrieved from
  7. Sharma, A.K., Basu, I., & Singh, S. (2018). Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial. The Journal of Alternative and Complementary Medicine, 24(3), 243-248. doi: 10.1089/acm.2017.0183. Retrieved from