Possible benefits and side effects of ashwagandha

We're all on the hunt for that one miraculous supplement that can tackle the physical and mental challenges of our daily lives, and some believe that ashwagandha is the answer. This root falls into the adaptogen category, which includes medicinal plants that are famous in alternative medicine for their knack to help our bodies handle stress. Studies have uncovered numerous potential benefits of ashwagandha, such as relieving stress, easing pain, boosting cognitive function, and much more. However, it's important to note that this supplement isn't without its risks. 

Though research shows that most people tolerate ashwagandha with no problems, that might not be the case for everyone. It’s important to understand all the potential side effects of ashwagandha and speak to your healthcare provider before incorporating the herb into your diet.

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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 (a family of plants that contain small amounts of alkaloids). 

Ashwagandha extract is touted to have anxiolytic (anti-anxiety) and anti-inflammatory properties. It may also potentially boost testosterone levels and improve infertility in certain populations. Some studies also suggest that it can lower cortisol (stress hormone) levels in people with chronic stress. Continue reading for more information about the potential benefits of ashwagandha.

1. May increase thyroid function

Ashwagandha may support a healthy thyroid. 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), increased. Researchers believe this effect may happen due to ashwagandha's cortisol-lowering effect, but more research is needed. 

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

2. May calm symptoms of stress and anxiety

Several studies showed that Ashwagandha had a positive calming effect on participants’ anxiety when compared to traditional anxiety medications. One study from 2019 found that consuming 240 milligrams (mg) of ashwagandha a day significantly reduced participants’ self-reported anxiety symptoms and.

And an animal study suggested that the supplement was similarly effective as lorazepam (an anxiety medication) at reducing anxiety in rodents. That’s not to say that ashwagandha supplements are a cure-all for anxiety. Still, it may have a place in treating symptoms. 

3. May improve heart health

One study conducted in 2015 found that ashwagandha might improve cardiorespiratory endurance (the ability of the heart and lungs to deliver oxygen to muscles) in already healthy, athletic adults, which could have positive effects on overall heart health. 

4. May treat arthritis 

According to a study of 125 participants with rheumatoid arthritis, ashwagandha successfully soothed joint pain compared to the placebo. How does this work? Researchers believe ashwagandha is both anti-inflammatory and stops pain signals from traveling along the central nervous system.

5. May support cognitive function

Struggling to focus? Ashwagandha may give you the boost you need. One small study found significant improvements in participants’ reaction times, choice discrimination, digit symbol substitution, digit vigilance, and card sorting tests when taking ashwagandha extract compared to a placebo. While more research is needed, this study is a promising indication of the supplement’s cognitive benefits.

1. May worsen some thyroid conditions 

While ashwagandha may support a healthy thyroid, it can be dangerous for those with already elevated thyroid function or hyperthyroidism. 

For people whose thyroids are already working overtime and who take thyroid medication to lower their hormone output, ashwagandha could potentially be dangerous and interact poorly with their medication. Left untreated, rising thyroid hormone levels in someone with hyperthyroidism can lead to a serious condition called thyrotoxicosis. Thyrotoxicosis can lead to many conditions, including heart failure.

2. May dangerously lower blood pressure

Although some people might 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

3. May cause gastrointestinal (GI) tract problems

Animal studies have suggested that ashwagandha may protect against stress-induced gastric ulcers. However, these results don’t necessarily translate to humans. In fact, our gastrointestinal (GI) tracts can react poorly to too much ashwagandha. Large doses of this herb may lead to an upset stomach, vomiting, or diarrhea. More research is needed to fully understand the supplement’s impact on the human GI tract.

4. Not recommended for those who are pregnant or breastfeeding

First things first: pregnant people (and all people, for that matter) should always seek medical advice from a healthcare professional before starting any supplement, no matter how benign it seems. For those who are pregnant, trying to become pregnant, or breastfeeding, ashwagandha is not a safe tool for stress relief. The herb contains compounds that may cause miscarriage. If you're struggling with prenatal or postpartum mental health, talk to your healthcare provider about safe treatment options.

5. May lower blood sugar

While more research is needed, several animal studies suggest that ashwagandha may lower blood sugar levels. 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 worsen certain autoimmune disorders

Having a robust immune system that works hard for you is good, right? Not always. People with autoimmune diseases like 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 higher the immune function, the harder the body will fight. Since ashwagandha may boost your immune response, people with these health conditions should avoid ashwagandha. But again, more research is needed here. 

Ashwagandha supplements are available in several forms: capsule, liquid extract, and powder. Many popular health companies sell cocoa or superfood drink mixes containing ashwagandha. There is no one recommended daily dose for ashwagandha, and research varies. However, one study found that a dose between 250 and 600 milligrams per day is effective to relieve stress. Ashwagandha can be taken at any time of day, but some believe taking the supplement before bed may improve sleep. 

Ashwagandha, like other supplements, is only loosely regulated by the Food and Drug Administration (FDA) and the FDA doesn’t approve dietary supplements for safety and effectiveness. This means that you can’t be absolutely certain of the amount or quality of the product you’re consuming. Several cases of liver injury have been reported with ashwagandha use. When the products in question were investigated, many contained contaminants.  

As mentioned, ashwagandha is not safe for people who are pregnant, trying to become pregnant, or breastfeeding. The supplement may also react dangerously with other medications or medical conditions. If you’re taking medication for high blood pressure, blood sugar, or thyroid function, be sure to talk to a healthcare provider about ashwagandha. 

Always speak to your healthcare provider before incorporating any new supplement into your diet, including ashwagandha.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

June 01, 2023

Written by

Abbi Havens

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.