For most healthy adults, taking ashwagandha daily at doses of 300 to 600 mg of root extract is generally well tolerated in studies lasting up to about 12 weeks. Beyond that window, safety data gets thinner, and there are real risks worth knowing about, including rare but documented cases of liver injury and hormonal shifts that matter if you have certain health conditions.
What Clinical Trials Actually Show
Most clinical trials on ashwagandha have used daily doses ranging from 240 to 1,250 mg of root extract, with study durations typically running 8 to 12 weeks. An international taskforce from the World Federation of Societies of Biological Psychiatry and the Canadian Network for Mood and Anxiety Treatments provisionally recommends 300 to 600 mg daily of root extract (standardized to 5% withanolides) for anxiety. That range is the best-supported dose for daily use.
Within these trials, side effects tend to be mild: stomach upset, drowsiness, and occasional loose stools. The problem is that very few studies extend past three months, so there’s limited data on what happens when you take ashwagandha daily for six months, a year, or longer. That gap matters.
The Liver Injury Risk
Rare but serious cases of liver damage have been linked to ashwagandha. A review published in Pharmaceuticals documented cases where daily doses of 450 to 1,350 mg led to liver injury, with onset ranging from as little as 5 days to as long as 180 days of continuous use. Symptoms across cases followed a similar pattern: nausea, itching, dark urine, and jaundice. When researchers scored these cases using a standardized tool for assessing drug-induced liver injury, the relationship to ashwagandha was rated as “probable.”
One case involved a 36-year-old man who developed liver inflammation after six months of taking 450 mg three times daily. His liver enzymes were more than 10 times the normal upper limit on admission. A 30-year-old woman developed symptoms after just 45 days on 450 mg, with bilirubin levels more than 10 times normal. Both cases resolved after stopping the supplement, but they illustrate that liver injury can happen at commonly used doses and at different time points.
These cases are uncommon relative to the millions of people who take ashwagandha, but they’re worth paying attention to. If you develop nausea, itching, unusually dark urine, or yellowing of the skin or eyes while taking ashwagandha, stop and get your liver function checked.
Effects on Thyroid Hormones
Ashwagandha can increase levels of thyroid hormones T3 and T4, likely through its effects on the body’s stress response system. For people with normal or underactive thyroids, this shift may be subtle or even beneficial. But for anyone with an overactive thyroid (hyperthyroidism), ashwagandha can push hormone levels further in the wrong direction.
This also creates a problem if you take thyroid medication. Because thyroid drugs are carefully dosed to keep your hormones in a specific range, adding ashwagandha can disrupt that balance. If you’re on thyroid medication or have a thyroid condition, this supplement needs to be discussed with whoever manages your thyroid care before you start taking it daily.
Who Should Avoid It
Several groups face higher risks from daily ashwagandha use. Ashwagandha stimulates immune activity, which is a problem for people with autoimmune conditions. A systematic review in Lupus Science & Medicine identified ashwagandha among herbs implicated in triggering or flaring autoimmune diseases, including lupus, dermatomyositis, autoimmune hepatitis, and autoimmune blistering diseases. If your immune system already attacks your own tissues, ramping up that activity is the opposite of what you want.
Pregnant people should avoid ashwagandha entirely. No human studies have examined its safety during pregnancy, and there’s no reliable data to support its use in that context. If you become pregnant while taking it, stop.
Ashwagandha also appears to have sedative properties that can amplify the effects of certain medications. The National Center for Complementary and Integrative Health notes preliminary evidence that ashwagandha may increase the effects of benzodiazepines and other sedative or anti-anxiety drugs. If you take anything for sleep or anxiety, combining it with daily ashwagandha could produce stronger drowsiness or sedation than expected.
Cycling: A Practical Approach
Because long-term safety data beyond 12 weeks is limited, many practitioners suggest a cycling approach rather than continuous indefinite use. A common schedule is 8 to 12 weeks of daily use followed by a 2 to 4 week break. During the break, you reassess whether the supplement is still helping and watch for any side effects that may have been building gradually.
This isn’t a strict medical rule. There’s no clinical trial proving that cycling is safer than continuous use. It’s a precautionary strategy born from the fact that we simply don’t have good data on what years of uninterrupted ashwagandha use does to the body. If you restart after a break and find you feel the same without it, that’s useful information too.
How to Choose a Product
Not all ashwagandha supplements contain the same thing. Clinical trials typically use root extracts standardized to a specific concentration of withanolides, the active compounds in the plant. The most common standardizations are 2.5% or 5% withanolides per capsule. A 300 mg capsule standardized to 5% withanolides delivers about 15 mg of the active compounds. Products that don’t list withanolide content on the label make it impossible to know what dose you’re actually getting.
Whole root powder requires much larger amounts to achieve similar effects. Some trials used up to 12,000 mg of whole root granules daily (equivalent to about 6,000 mg of root powder), which is a very different product from a concentrated extract capsule. When comparing products, check whether you’re looking at an extract or a whole root powder, and whether the withanolide percentage is listed. Standardized extracts in the 300 to 600 mg range are closest to what’s been studied.
Supplements in the United States aren’t tested for safety or accuracy by the FDA before they reach shelves. Third-party testing seals (like NSF, USP, or ConsumerLab) offer some assurance that what’s on the label matches what’s in the bottle, and that contaminants like heavy metals are below harmful levels.