Ashwagandha, also known by its botanical name Withania somnifera, is a small woody plant with yellow flowers native to India and North Africa.
It’s classified as an adaptogen, as it’s believed to help your body manage stress better.
The plant — particularly its root — has been used for over 3,000 years as a natural Ayurvedic remedy against various ailments (1).
Modern science also links it to health benefits, such as reduced stress and anxiety and improved blood sugar levels, mood and memory.
This article reviews the optimal dosages needed to reap different health benefits.
Ashwagandha is best known for its stress-lowering effects.
The medicinal herb appears to help lower levels of cortisol, a hormone produced by your adrenal glands in response to stress. More specifically, daily doses of 125 mg to 5 grams for 1–3 months have shown to lower cortisol levels by 11–32% (2, 3, 4).
Summary Ashwagandha seems effective at lowering symptoms of stress and anxiety. Most benefits are linked to dosages of 500–600 mg per day taken for at least one month.
In one small, 4-week study in 25 people, ashwagandha reduced fasting blood sugar levels three times more than a placebo (8).
In another study in people with type 2 diabetes, an ashwagandha supplement taken for 30 days helped lower fasting blood sugar levels as effectively as oral diabetes medication (9).
Dosages used in these studies varied between 250 mg to 3 grams and were generally split into 2–3 equal doses spread evenly over the day.
Summary Ashwagandha may help lower blood sugar levels. Benefits appear to start at dosages as little as 250 mg per day.
Ashwagandha may help boost fertility and promote reproductive health, especially in men.
In one 3-month study in 75 men experiencing infertility, five grams of ashwagandha daily increased sperm count and motility (10).
In another study in highly stressed men, five grams of ashwagandha per day also led to improved sperm quality. Moreover, by the end of the 3-month study, 14% of their partners had become pregnant (4).
Summary Five grams of ashwagandha per day may boost fertility in men in as little as three months.
Supplementing with ashwagandha may also increase muscle mass and strength.
In one 8-week study, men given 500 mg of this medicinal herb per day increased their muscular power by 1%, whereas the placebo group experienced no improvements (13).
In another study in men, 600 mg of ashwagandha per day for eight weeks led to a 1.5–1.7 times larger increase in muscle strength and 1.6–2.3 times higher increase in muscle size, compared to a placebo (11).
Similar effects were observed with 750–1,250 mg of ashwagandha per day taken for 30 days (7).
Summary Daily doses of 500 mg of ashwagandha may provide small increases in muscle mass and strength in as little as eight weeks. While most studies have focussed on men, some research suggests women may reap the same benefits.
Ashwagandha may also help lower inflammation and boost your immunity.
Research shows that 12 ml of ashwagandha root extract per day may increase levels of immune cells, which help fight infection (14).
Moreover, a daily intake of 250–500 mg of ashwagandha over 60 days may reduce C-reactive protein levels by up to 30%, which is a marker of inflammation, (2).
Summary Ashwagandha may lower inflammation and help fight infection. Supplements containing at least 250 mg of ashwagandha or 12 ml of ashwagandha extract appear to offer the most benefits.
Ashwagandha is traditionally used in Ayurveda to help boost memory, and some scientific studies support this practice.
For instance, in a small, 8-week study, 300 mg of ashwagandha root extract twice a day improved general memory, attention and task performance significantly more than a placebo (15).
Moreover, healthy men given 500 mg of the medicinal herb per day for two weeks performed significantly better on tests for task performance and reaction time, compared to those given a placebo (16).
That being said, human research in this area is limited and more is needed before strong conclusions can be drawn.
Summary Consuming 500–600 mg of ashwagandha root extract per day may boost various aspects of memory. However, more studies are needed to confirm these effects.
Ashwagandha is considered safe for most people.
However, pregnant or breastfeeding women, as well as people with autoimmune diseases, such as lupus, rheumatoid arthritis, type 1 diabetes and Hashimoto’s disease, may need to avoid it.
Ashwagandha may also interact with thyroid, blood sugar and blood pressure medications.
People taking these types of medication should consult with their doctor before supplementing with the medicinal herb.
Keep in mind that most of the studies on ashwagandha were small and of low quality. For this reason, the information on the effectiveness and safety of dosages may be inaccurate. More research is needed.
Summary Ashwagandha is considered safe for most people. However, pregnant or breastfeeding women, people with autoimmune disorders and those taking certain medications may need to avoid it.
Ashwagandha is a medicinal herb that may offer several health benefits, such as improved blood sugar, inflammation, mood, memory, stress and anxiety, as well as a boost in muscle strength and fertility.
Dosages vary depending on your needs, but 250–500 mg per day for at least one month seem effective.