Is ashwagandha safe? Who should not take it?

Ashwagandha may sound like a wonder herb—people claim it can help with stress, anxiety, low testosterone, diabetes, and autoimmune diseases, among other health problems. But is ashwagandha safe for everyone? Can you take ashwagandha daily? Let’s dive into more details about the safety profile of this herb.

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Ashwagandha (Withania somnifera) is sometimes referred to as "Indian ginseng" or "winter cherry." Withania somnifera belongs to the nightshade family of plants, and its suspected active ingredients include alkaloids, steroidal lactones, saponins, and withanolides. 

Ashwagandha is commonly used in the form of traditional Indian medicine known as Ayurvedic medicine or, simply, Ayurveda. It is an adaptogen, which are herbs and roots that may help balance physical, mental, and emotional stresses in the body—in short, they may aid your body in adapting to various stressors. 

Ashwagandha is considered to be generally safe (Verma, 2021). However, since research on herbal medications is limited and ashwagandha formulations vary depending on where you buy them from, you should be careful and consult your healthcare provider before starting herbal supplements.

While adverse effects are uncommon, some people may experience gastrointestinal upset, diarrhea, nausea, vomiting, and drowsiness in large doses (NIDDK, 2019). 

Small clinical trials on ashwagandha sometimes demonstrate mild side effects, including nasal congestion (rhinitis), cough and cold, constipation, changes in appetite, and increased libido (Chandrasekhar, 2012; Raut, 2012). 

Unfortunately, the use of ashwagandha by certain people may lead to serious side effects. Groups of people who should NOT use ashwagandha include:

• People who are pregnant or breastfeeding: If you are pregnant or breastfeeding, be sure to check with your healthcare provider before starting any herbal supplements. Ashwagandha is likely unsafe to use during pregnancy because there is some evidence to suggest that it may cause miscarriages. There is not enough reliable information on ashwagandha and breastfeeding to know how ashwagandha affects breastmilk, so err on the side of caution and avoid it (MedlinePlus, 2020).

• People with diabetes: Animal studies suggest that Withania somnifera might lower blood sugar levels, which seems like a good thing for people with diabetes (Durg, 2020). However, since people with diabetes are usually on blood sugar lowering medications, the addition of ashwagandha could cause blood sugar levels to drop too low unexpectedly, and this can be very dangerous (MedLinePlus, 2020).

• People with high blood pressure: Studies suggest that ashwagandha has a blood pressure-lowering effect (Andallu, 2000). This effect could potentially be a problem for people with either high or low blood pressure. People with high blood pressure, especially those on prescription medications for this condition, may experience an interaction between their prescribed drugs and ashwagandha or have an unexpected drop in their blood pressure. For people with already low blood pressure, ashwagandha could cause their levels to drop dangerously low (MedlinePlus, 2020).

• People having surgery: Data from animal trials shows that ashwagandha may have a sedating or tranquilizing effect, slowing down the central nervous system (Mishra, 2000). When combined with ashwagandha, drugs used during and after surgery may increase this nervous system slowdown. You should stop taking ashwagandha at least two weeks before surgery, and be sure to let your surgeon know about any medications and supplements you are taking (MedlinePlus, 2020).

• People with stomach ulcers: This herb may irritate your gastrointestinal tract; therefore, you should avoid ashwagandha if you have stomach ulcers (MedlinePlus, 2020). 

• People with autoimmune conditions: Many people use ashwagandha to boost their immune system, as research suggests it may increase immune activity (Vetvivka, 2011; Priyanka, 2020). While this may be beneficial for some, it can be detrimental to others, especially people suffering from autoimmune diseases like multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis (MedlinePlus, 2020). By activating the immune system, this ayurvedic herb may worsen autoimmune symptoms.

• People with thyroid disorders: Thyroid abnormalities can be frustrating for those dealing with them. Clinical studies have shown that ashwagandha may increase thyroid hormone levels in people with decreased thyroid function that is not low enough to warrant medical therapy (subclinical hypothyroidism). However, if someone takes thyroid hormone medications to treat abnormal thyroid activity, combining them with ashwagandha may cause thyroid hormone levels to rise above normal. Similarly, if you have elevated thyroid activity (hyperthyroidism), taking ashwagandha could still cause rising thyroid hormone levels. If levels increase beyond a certain point, you could develop thyrotoxicosis, a serious medical condition  (Sharma, 2018).

Much more research is needed before ashwagandha becomes a mainstream remedy, but research suggests that ashwagandha supplements may offer several potential health benefits, including (Mandlik Ingawale, 2021):

• Boosting testosterone levels

• Improving male fertility by increasing sperm count

• Reducing blood sugar levels

• Lowering cortisol levels

• Decreasing anxiety and depression

• Reducing inflammation

• Increasing muscle mass and muscle strength

• Lowering cholesterol

• Improving sleep

It is important to know that there is no standard dose for ashwagandha extract supplements. 

Studies looking at different uses for ashwagandha extract dosages ranging from 125 mg to 5 g, often divided into 2–4 doses per day (Mahdi, 2009). 

You’ll see a wide range of doses in the supplements online or at your local health store. 

Lower amounts tend to be used in supplements with multiple ingredients, whereas higher doses are mostly found in ashwagandha-specific supplements. 

Since people can react differently to supplements, starting at a low dose will help you gauge your tolerance. You may want to start with one pill or capsule a day to see how you react and slowly add capsules until you reach the full suggested dose. Before going into the upper dosage ranges, you should discuss this with your healthcare provider. 

Most people consider ashwagandha a relatively safe herbal supplement that can help with conditions like anxiety, stress, low testosterone, among other diseases. However, the research is limited, and scientists don't know the exact health benefits or the optimal doses. Talk to your healthcare provider before starting herbal supplements like ashwagandha, especially if you have any of the medical conditions mentioned.

Before starting a new supplement, discuss your medical history with your healthcare professional, including any medications you are taking. This can reduce your risk of side effects or safety issues. If you experience side effects while taking ashwagandha, check in with your provider and stop taking the supplement if your symptoms worsen.

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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

September 07, 2021

Written by

Chimene Richa, MD

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.