Ashwagandha interacts with several categories of medications, primarily sedatives, thyroid drugs, immunosuppressants, and blood sugar-lowering treatments. Because it has real, measurable effects on brain chemistry, hormone levels, and immune function, combining it with medications that target those same systems can amplify or interfere with their effects.
Sedatives and Sleep Medications
Ashwagandha acts on the same brain pathway that benzodiazepines and barbiturates target. It increases the brain’s levels of GABA, a calming neurotransmitter, and promotes chloride flow into nerve cells, which slows neural activity and produces sedation. In animal studies, ashwagandha significantly prolonged sleep duration in models using pentobarbital, a barbiturate. It also counteracted caffeine-induced wakefulness.
This matters because if you’re taking a prescription sedative, a sleep aid, or an anti-anxiety medication that works through the same calming pathway, ashwagandha can stack on top of those effects. The result could be excessive drowsiness, slowed breathing, or deeper sedation than intended. This applies to benzodiazepines like lorazepam and alprazolam, barbiturates, and other central nervous system depressants including alcohol.
Thyroid Medications
Ashwagandha raises thyroid hormone levels. A clinical trial of 50 people with mildly underactive thyroids found that 600 mg per day for eight weeks increased both T3 and T4 (the two main thyroid hormones) while lowering TSH, the hormone that signals the thyroid to produce more. A separate study in healthy men taking 500 mg daily also showed small T4 increases.
This creates a two-sided problem. If you take thyroid replacement medication like levothyroxine (Synthroid), desiccated thyroid (Armour Thyroid), or liothyronine (Cytomel), ashwagandha could push your hormone levels higher than your prescribed dose intends. And if you take anti-thyroid medication like methimazole or propylthiouracil for an overactive thyroid, ashwagandha works against those drugs by stimulating more hormone production. The exact mechanism behind this thyroid effect isn’t fully understood, though it likely involves ashwagandha’s influence on the stress response system. Either way, combining it with thyroid medications can throw off the careful balance your dosage is designed to maintain.
Diabetes and Blood Sugar Medications
Ashwagandha can lower blood glucose levels, though the evidence is mixed. Some clinical studies have shown reductions in both fasting blood sugar and HbA1c (a marker of long-term blood sugar control) in people with diabetes. Lab research suggests it works by increasing glucose uptake in muscle and fat cells while also boosting insulin secretion.
If you take insulin or oral diabetes medications, adding ashwagandha introduces a risk of hypoglycemia, where blood sugar drops too low. Symptoms of hypoglycemia include shakiness, dizziness, sweating, and confusion. The interaction isn’t guaranteed since not all studies have found a blood sugar effect, but the possibility is real enough to warrant caution, especially if your blood sugar is already tightly controlled with medication.
Immunosuppressants
Ashwagandha stimulates the immune system. That’s beneficial for most healthy people, but it creates a direct conflict with immunosuppressant drugs, which are prescribed specifically to dial the immune system down. The National Institutes of Health flags this as a known interaction category.
People take immunosuppressants after organ transplants, for autoimmune diseases like lupus, rheumatoid arthritis, and multiple sclerosis, and during certain cancer treatments. In autoimmune conditions, the immune system is already overactive and attacking the body’s own tissues. As Memorial Sloan Kettering Cancer Center notes, ashwagandha can “rev up your immune system even more, and that can be harmful.” Taking it alongside drugs meant to suppress that overactivity could undermine the treatment entirely.
Anesthesia and Surgery
Because ashwagandha has sedative properties and can amplify the effects of barbiturates and benzodiazepines, it poses a concern before surgical procedures. Anesthesia relies on precise control of sedation depth, and an herbal supplement that independently promotes sedation through similar brain pathways adds an unpredictable variable. The University of Texas at El Paso lists ashwagandha among herbs to stop before surgery specifically because of its potential to intensify anesthesia effects. Most surgical teams recommend discontinuing herbal supplements at least two weeks before a planned procedure.
Hormone-Sensitive Conditions
Ashwagandha influences multiple hormones, including thyroid hormones, cortisol, and testosterone. Several studies have shown it raises testosterone levels in men, which is often marketed as a benefit but becomes a concern for anyone with a hormone-sensitive condition. Prostate cancer, certain breast cancers, endometriosis, and uterine fibroids can all be fueled by hormonal shifts. If you have a condition that responds to hormone levels, ashwagandha’s broad hormonal activity is worth discussing with whoever manages your care before adding it.
Liver Considerations
Ashwagandha is generally safe for the liver. A 2025 meta-analysis in Frontiers in Nutrition reviewed the full body of evidence and classified ashwagandha as negative for herb-induced liver injury, meaning no cases in clinical studies met the formal criteria for liver toxicity. Of 338 molecules identified in the plant, only two showed predicted liver toxicity in modeling studies, and neither was found in the root, which is the part used in supplements.
That said, rare case reports of liver injury do exist. Most involved confounding factors: pre-existing liver conditions, simultaneous use of other supplements, or unusually high doses. In clinical monitoring studies, a small number of participants showed mild liver enzyme elevations that returned to normal after stopping the supplement. The proposed explanations include rare immune-mediated reactions or interactions with other medications that alter how the liver processes compounds. If you take medications that are already hard on the liver, or if you have existing liver disease, the combination could increase risk even though ashwagandha alone is unlikely to cause problems.
Medications That Share Similar Effects
A useful rule of thumb: ashwagandha is most likely to cause problems when paired with a medication that does something ashwagandha already does on its own. It lowers blood sugar, so it stacks with diabetes drugs. It promotes sedation, so it stacks with sleep aids and anti-anxiety medications. It raises thyroid hormones, so it conflicts with both thyroid replacement and anti-thyroid drugs. It stimulates the immune system, so it opposes immunosuppressants. It influences hormones, so it complicates hormone-sensitive treatments.
None of these interactions are guaranteed to cause harm in every person, but they represent real pharmacological overlaps. The supplement industry doesn’t require interaction testing the way prescription drugs do, so much of the evidence comes from case reports, small trials, and mechanistic studies rather than large-scale interaction research. If you take any of the medication categories above, the practical move is to bring it up with your prescriber before starting ashwagandha so your labs and symptoms can be monitored appropriately.