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Last updated November 14, 2019. 6 minute read

Does ashwagandha have side effects?

This Ayurvedic herb acts especially on cortisol levels in the body, which are tied to other key functions. That means this supplement may not be right for everyone. Ashwagandha may interact with some prescription medications, so you should always talk to a medical professional before beginning a regimen.

Linnea Zielinski Written by Linnea Zielinski
Reviewed by Mike Bohl, MD, MPH

Adaptogens are a family of medicinal plants such as herbs and roots popular in alternative medicine that help the body adapt to or deal with all kinds of stressors, from physical to mental. That’s a powerful concept and one that’s recently caught the attention of the mainstream wellness industry in the United States. But it’s actually been around for centuries, and these plants have been popular mainstays of Ayurvedic, Indian, and African traditional medicine. One of these essential herbs is ashwagandha or Withania somnifera, also called 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 the potential side effects.


  • Ashwagandha is a medicinal plant traditionally used in alternative medicine practices such as Ayurveda.
  • As an adaptogen, it might be able to help your body adjust to different types of stressors, from physical (like inflammation) to mental (like anxiety).
  • This Ayurvedic herb acts especially on cortisol levels in the body, which are tied to other key functions. That means this supplement may not be right for everyone.
  • Ashwagandha may interact with some prescription medications, so you should always talk to a medical professional before beginning a regimen.
  • Pregnant women should avoid this herbal supplement.

Ashwagandha health benefits

It’s worth noting that ashwagandha is generally well-tolerated, and its potential health benefits are wide-ranging. It gets many of its health benefits from its withanolides, steroids that are naturally-occurring in nightshades. Withania somnifera could potentially boost testosterone levels (Ahmad, 2010) and improve male infertility (Mahdi, 2011) in certain populations, and ease cortisol levels (Chandrasekhar, 2012) in people with chronic stress. Although it gets its name from its ability to boost strength but also its unique smell, the herb comes as capsules as well as powder if you find it off-putting. But since it’s as easy to get as ordering online or running to a supplement store, you should do your homework to make sure you’re buying from a trust-worthy brand.

Possible ashwagandha side effects

Even if you’re buying from the best sources, everyone reacts to supplements differently. Though most research shows that many people handle Withania somnifera 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.

May increase thyroid function

This may sound like welcome news for some, like those suffering from conditions characterized by low thyroid function such as hypothyroidism and Hashimoto’s, but it can be dangerous for people with already elevated thyroid function, or hyperthyroidism. Participants with subclinical hypothyroidism saw normalization of both of the main thyroid hormones triiodothyronine (T3) and thyroxine (T4) when given ashwagandha root extract in a 2018 study (Sharma, 2018). Researchers believe that this effect may happen due to ashwagandha’s cortisol-lowering effect, but more work needs to be done to confirm that. 

This study sparks hope that Withania somnifera may prove helpful in the treatment of subclinical hypothyroidism, suppressed 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 a number of conditions, including heart failure.

Can decrease blood pressure levels

Although some people would welcome a supplement that lowers blood pressure to their routine with open arms, this side effect of Withania somnifera can be dangerous for others. Many people with hypertension, or high blood pressure, are on a prescription medication monitored by their primary care physician. This Ayurvedic herb can interfere with these drugs’ actions in the body. Alternatively, people with naturally low blood pressure are at risk of potentially driving this too low with this supplement. That’s why you should always seek out medical advice before adding something new to your regimen.

May irritate GI tract

Ashwagandha is adaptogenic, meaning that in some people, it’s a Swiss Army knife for treating stress. Along with its anxiolytic (anti-anxiety) and anti-inflammatory properties, Withania somnifera may also act as a protectant against stress-induced gastric ulcers and even aspirin-induced gastric ulcers. The study (Singh, 1982) was done on mice, and animal studies don’t always translate to us, so human studies are needed to confirm that these protective qualities hold true.

But our gastrointestinal (GI) tracts can also get too much ashwagandha. Constipation and decreased appetite were side effects observed in one study (Chandrasekhar, 2012), and large amounts can even cause enough gastrointestinal distress to cause ulcers (not the same kind it helps prevent). Although some participants in the placebo-controlled study also mentioned experiencing abdominal pain and diarrhea, they were in the placebo group, and their side effects cannot be attributed to the use of ashwagandha.

Can induce early pregnancies or miscarriages

First things first: pregnant women should always seek medical advice from a healthcare professional before starting any supplement, so 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, premature birth, or uterine contractions, according to the National Institutes of Health (NIH, 2020.). If you’re feeling stressed, talk to your healthcare provider about potential treatment plans.

May decrease blood sugar

More research does need to be done in this area, but several studies done in rats have indicated that ashwagandha can lower blood sugar (Noshahr, 2014). For example, both glucose tolerance and insulin sensitivity were improved in diabetic rats through supplementation with ashwagandha extract in one study (Anwer, 2008). But research in humans is limited, for now. One study (Andallu, 2000) one in humans also showed blood sugar-lowering effects of the Ayurvedic herb, however, the study size was very small, so we cannot be sure of the true effects.

May increase immune activity

Having a strong immune system that’s working hard for you is good, right? Not always. For people with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, or multiple sclerosis, this can make their symptoms worse. Autoimmune diseases are characterized by the body attacking itself, so the more immune function, the harder it will fight. Since ashwagandha has been shown to boost immune response (Vetvicka, 2011), it’s advised that people with autoimmune diseases avoid this herbal supplement.

Not all manufacturers of ashwagandha powder or ashwagandha root extract are FDA-regulated

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 actually 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 the products in question were investigated, it turned out that many contained contaminants (NIDDKD, 2019). Avoid these safety concerns by buying from a company you can trust.