Withania somnifera, known as ashwagandha, has a role in ayurvedic medicine for a wide range of health conditions. Ashwagandha is purported as useful for relieving stress, fatigue, pain and gastrointestinal problems, and treating diabetes, rheumatoid arthritis and epilepsy. Ashwagandha interacts with several types of prescription medicine, so consult your health care provider before taking this herbal remedy.
If you take thyroid medicine, consult your doctor before using ashwagandha. Animal research and one case study indicate that the herb might increase serum concentration of thyroid hormones, according to Ray Sahelian, a medical doctor who specializes in natural supplements. The combination could result in excess thyroid hormone in the body, which has many negative effects. Some symptoms of high thyroid hormone levels include fatigue, increased appetite, sweating, restlessness, diarrhea, hair loss, insomnia, itching and high blood pressure.
Ashwagandha might increase the sedative effects of benzodiazepines, prescribed for conditions such as panic disorder and anxiety, and of barbiturates, primarily used for epilepsy. Take ashwagandha with these drugs only under your doctor's supervision, recommends the Langone Medical Center at New York University. Some benzodiazepine drugs include alprazolam, known as the brand Xanax; clonazepam, known as Klonopin; diazepam, known as Valium; lorazepam, known as Ativan; and triazolam, known as Halcion. Some barbiturates include phenobarbital, pentobarbital and secobarbital.
Because ashwagandha supports immune system function, it might interact with medications designed to reduce immune system activity, known as immunosuppressants, according to the University of Maryland Medical Center. The combination could decrease the effectiveness of these medications. Examples of immunosuppressants include azathioprine, cyclosporine, mycophenolate, prednisone and corticosteroids. Doctors prescribe immunosuppressants for people with conditions such as rheumatoid arthritis, psoriasis and ulcerative colitis, and to prevent rejection of organ transplants.
The April 2008 issue of "Therapeutic Drug Monitoring" notes that some herbal products interfere with methodology used to measure drug levels in a patient's bloodstream. Ashwagandha interferes with immunoassay measurements of digoxin, a medication primarily used for treating congestive heart failure and abnormal heart rhythms. This interference is likely due to a similarity in chemical structure, according to Drugs.com. Consult your doctor before taking ashwagandha if you use digoxin.