Ashwagandha interacts with several categories of medications, including thyroid hormones, sedatives, blood pressure drugs, diabetes medications, and immunosuppressants. It also affects hormone levels and liver enzyme activity in ways that can change how your body processes other drugs. If you take any prescription medication, these interactions are worth understanding before adding ashwagandha to your routine.
Thyroid Medications
This is one of the most clinically significant interactions. Ashwagandha stimulates thyroid hormone production, and combining it with thyroid medication can push levels into a dangerous range. In animal studies, ashwagandha increased the thyroid hormone T4 by roughly 111% over 20 days. In humans, the consequences have been serious: a 73-year-old woman who self-treated her hypothyroidism with ashwagandha for two years developed thyrotoxicosis and a heart arrhythmia. Her TSH dropped to nearly undetectable levels. After she stopped taking ashwagandha, her thyroid function returned to normal within five weeks.
In another reported case, a 32-year-old healthy woman developed poor appetite, weight loss, shakiness, and palpitations six weeks after starting an ashwagandha supplement and shortly after increasing the dose. Her thyroid hormones were well above normal range. Symptoms resolved after she stopped the supplement.
Adding to the concern, some commercially available ashwagandha supplements have been found to contain actual T3 and T4 hormones at levels exceeding the doses used to treat hypothyroidism. If you take levothyroxine or any thyroid hormone replacement, ashwagandha poses a real risk of pushing you into hyperthyroidism.
Sedatives and Anti-Anxiety Medications
Ashwagandha has its own sedative properties, which is part of why people take it for stress and sleep. But those same calming effects can stack on top of prescription sedatives. The National Center for Complementary and Integrative Health notes preliminary evidence that ashwagandha may increase the effects of benzodiazepines like diazepam (Valium) and alprazolam (Xanax), along with other sedative and anti-anxiety drugs.
The practical risk is excessive drowsiness, slowed breathing, and impaired coordination. This applies broadly to anything that depresses central nervous system activity, including sleep medications, barbiturates, and anticonvulsants. If you already feel groggy or sedated on your current medication, adding ashwagandha could amplify that effect.
Blood Sugar and Diabetes Medications
Ashwagandha lowers blood sugar on its own. Animal research shows it improves glucose tolerance, enhances insulin sensitivity, and restores function in the insulin-producing cells of the pancreas. These are meaningful metabolic effects, and they run parallel to what diabetes medications already do.
The concern is additive: if your medication is calibrated to bring your blood sugar to a safe range, ashwagandha could push it lower than intended. Symptoms of blood sugar dropping too low include dizziness, shakiness, confusion, sweating, and in severe cases, loss of consciousness. This interaction applies to insulin as well as oral diabetes medications.
Blood Pressure Medications
Ashwagandha can lower blood pressure, which creates the same type of additive risk seen with diabetes drugs. If you already take medication to manage high blood pressure, adding ashwagandha may cause your pressure to drop further than expected. Signs of blood pressure going too low include lightheadedness, dizziness (especially when standing up), blurred vision, and fatigue. The NIH lists blood pressure medications among the drugs ashwagandha is known to potentially interact with.
Immunosuppressants
Ashwagandha is an immune stimulant. It shifts your immune system’s signaling environment by boosting certain activating signals while dialing others down. Specifically, it increases the activity of immune pathways that ramp up your body’s defense responses.
This is a direct problem if you take immunosuppressant medications, which are designed to keep your immune system quieter. People take these drugs after organ transplants or to manage autoimmune conditions like lupus or rheumatoid arthritis. Ashwagandha could work against those medications by reactivating the very immune responses your treatment is trying to suppress. The NIH recommends against ashwagandha for people with autoimmune disorders, and it is also not recommended for anyone about to have surgery, partly because of its immune and blood-related effects.
Hormone Therapy
Ashwagandha meaningfully shifts hormone levels. In a randomized, placebo-controlled study of overweight men, ashwagandha supplementation increased testosterone by 14.7% and the hormone precursor DHEA-S by 18% compared to placebo. It also showed a trend toward lowering estradiol (a form of estrogen) by about 12% and cortisol by about 8%, though those changes weren’t statistically significant.
These shifts matter if you’re on hormone replacement therapy of any kind. For testosterone therapy, ashwagandha could push levels higher than intended, which carries risks for people with cardiovascular disease, prostate conditions, or sleep apnea. For estrogen-based therapies, the potential estrogen-lowering effect could work against your treatment goals. And because ashwagandha influences cortisol, it could also interact with corticosteroid medications in unpredictable ways.
Liver Enzyme Effects
Your liver uses a family of enzymes to break down most medications. Ashwagandha has been shown to affect at least one of the most important of these, CYP3A4, which is responsible for metabolizing a large share of all prescription drugs. Research using human liver cells found that ethanolic ashwagandha root extracts changed CYP3A4 enzyme expression and activity.
This is significant because altering CYP3A4 can change how quickly your body processes other drugs. If ashwagandha slows this enzyme down, medications that rely on CYP3A4 for breakdown could accumulate to higher levels in your blood than expected, increasing the risk of side effects. This enzyme handles everything from certain cholesterol medications to some antidepressants, antihistamines, and heart drugs, so the potential for indirect interactions is broad.
Liver Safety
Ashwagandha itself can, in rare cases, cause liver injury. Clinical trials have not shown significant liver enzyme elevations during use, and in one study of 45 patients taking ashwagandha-containing preparations for six weeks, none developed abnormal liver values. However, case reports of clinically apparent liver damage have emerged from people taking commercial ashwagandha products.
Some of those cases involved products that were tested and confirmed to contain ashwagandha without contaminants, making it likely that ashwagandha itself was the cause. The NIH’s LiverTox database rates ashwagandha as a “likely cause of clinically apparent liver injury,” and recommends avoiding it entirely if you have cirrhosis or advanced liver disease. If you take other medications that are hard on the liver, this adds another layer of risk worth considering.