Understanding Ashwagandha
Ashwagandha (Withania somnifera) is an evergreen shrub native to India, the Middle East, and parts of Africa, used for thousands of years in traditional Ayurvedic medicine [1.3.3, 1.9.2]. Often referred to as an "adaptogen," it's popularly used to help the body manage stress [1.9.2]. Its benefits are attributed to active compounds like withanolides [1.9.2]. People take ashwagandha for various reasons, including stress reduction, anxiety relief, and to improve sleep [1.3.4]. While generally considered safe for short-term use (up to 3 months), its pharmacological effects mean it can interact with a wide range of conventional medications [1.2.3]. It's vital to consult a healthcare provider before combining this potent herb with any prescription drug.
Medications That Interact with Ashwagandha
Evidence shows ashwagandha can alter the effects of several classes of drugs, potentially leading to adverse outcomes [1.2.3]. The primary interactions involve medications for the central nervous system, endocrine system, and immune system.
Sedatives and CNS Depressants
Ashwagandha possesses natural sedative properties; its botanical name, somnifera, is Latin for "sleep-inducer" [1.3.4]. When combined with other central nervous system (CNS) depressants, it can cause additive effects, leading to excessive drowsiness, slowed breathing, and impaired coordination [1.8.3]. This can be dangerous, especially when driving or operating heavy machinery [1.3.3].
Commonly interacting sedatives include [1.8.1, 1.8.2]:
- Benzodiazepines: Often prescribed for anxiety, examples include alprazolam (Xanax), clonazepam (Klonopin), and diazepam (Valium) [1.8.1, 1.3.3].
- Barbiturates: Such as phenobarbital [1.8.1].
- Sleep Medications: Including zolpidem (Ambien) and eszopiclone [1.8.2, 1.2.4].
- Opioid Pain Medications: Such as oxycodone [1.8.1].
Thyroid Medications
Ashwagandha may increase thyroid hormone levels, specifically triiodothyronine (T3) and thyroxine (T4) [1.4.2, 1.3.6]. This poses a significant risk for individuals on thyroid medication.
- For Hypothyroidism: If you take thyroid replacement hormones like levothyroxine (Synthroid), combining them with ashwagandha could lead to an excess of thyroid hormone in the body, a condition called thyrotoxicosis [1.4.2, 1.4.6]. Symptoms can include a rapid heartbeat, nervousness, trouble sleeping, and mood swings [1.4.2].
- For Hyperthyroidism: For those with an overactive thyroid taking anti-thyroid medications like methimazole or propylthiouracil, ashwagandha can work against the medication by further stimulating the thyroid, potentially worsening the condition [1.4.5, 1.4.1].
Immunosuppressants
Immunosuppressant drugs are used to dampen the immune system's response, which is crucial for individuals with autoimmune diseases (like rheumatoid arthritis or lupus) or those who have had an organ transplant [1.5.1]. Ashwagandha appears to have the opposite effect—it can increase the activity of the immune system [1.5.2]. By stimulating the immune system, ashwagandha may decrease the effectiveness of immunosuppressant medications, potentially leading to a flare-up of an autoimmune condition or increasing the risk of organ transplant rejection [1.5.2, 1.9.2].
Examples of immunosuppressants include [1.5.1, 1.5.4]:
- Corticosteroids like prednisone.
- Azathioprine (Imuran).
- Tacrolimus (Prograf).
- Cyclosporine (Neoral, Sandimmune).
Diabetes Medications (Antidiabetics)
Research suggests ashwagandha can lower blood sugar levels [1.6.6]. While this might sound beneficial, it can be dangerous when combined with medications designed to do the same thing. The additive effect can cause blood sugar to drop too low, a condition known as hypoglycemia [1.6.5]. Symptoms of hypoglycemia include dizziness, confusion, shakiness, sweating, and in severe cases, loss of consciousness [1.6.2]. Close monitoring of blood sugar is essential if this combination is approved by a doctor [1.6.2].
Examples of diabetes medications include [1.6.5]:
- Insulin
- Metformin (Glucophage)
- Glipizide (Glucotrol)
- Sitagliptin (Januvia)
Blood Pressure Medications (Antihypertensives)
Similar to its effect on blood sugar, ashwagandha may also lower blood pressure [1.7.2]. Taking it alongside prescribed antihypertensive drugs can cause blood pressure to fall to dangerously low levels (hypotension) [1.7.2]. This can lead to dizziness, lightheadedness, and fainting [1.7.1].
Classes of blood pressure medications to be cautious with include [1.7.2, 1.7.5]:
- ACE inhibitors (e.g., ramipril)
- Angiotensin II receptor blockers (ARBs) (e.g., losartan)
- Beta-blockers (e.g., atenolol)
- Calcium channel blockers (e.g., amlodipine)
- Diuretics (e.g., furosemide, hydrochlorothiazide)
Medications That Can Harm the Liver (Hepatotoxic Drugs)
Although rare, there have been reports linking ashwagandha supplements to liver injury [1.3.2, 1.9.5]. Combining ashwagandha with other medications known to carry a risk of liver damage could increase this potential harm [1.5.1]. It's best to avoid ashwagandha if you have existing liver disease or are taking other hepatotoxic drugs [1.9.5].
Ashwagandha Drug Interaction Summary
| Medication Class | Mechanism of Interaction | Potential Outcome | Examples of Medications |
|---|---|---|---|
| Sedatives / CNS Depressants | Additive sedative effects [1.8.3]. | Excessive drowsiness, slowed breathing, impaired coordination [1.8.3]. | Alprazolam (Xanax), Zolpidem (Ambien), Phenobarbital [1.8.1, 1.3.3]. |
| Thyroid Medications | May increase the body's production of thyroid hormones (T3 and T4) [1.4.2]. | Can lead to thyrotoxicosis in those on hormone replacement or reduce the efficacy of anti-thyroid drugs [1.4.6, 1.4.5]. | Levothyroxine (Synthroid), Methimazole [1.4.5]. |
| Immunosuppressants | May increase immune system activity, counteracting the drug's effect [1.5.2]. | Decreased medication effectiveness, potential worsening of autoimmune conditions, organ rejection risk [1.5.4, 1.9.2]. | Prednisone, Tacrolimus (Prograf), Cyclosporine [1.5.1, 1.5.4]. |
| Diabetes Medications | Additive blood-sugar-lowering effect [1.6.2]. | Hypoglycemia (dangerously low blood sugar) [1.6.5]. | Insulin, Metformin, Glipizide [1.6.5]. |
| Blood Pressure Medications | Additive blood-pressure-lowering effect [1.7.2]. | Hypotension (dangerously low blood pressure) [1.7.2]. | Lisinopril, Losartan, Amlodipine, Atenolol [1.7.4, 1.7.5]. |
Conclusion
While ashwagandha is a popular herbal supplement with a long history of use, its powerful effects on the body mean it is not suitable for everyone. It has the potential to cause significant interactions with several major classes of medications, including sedatives, thyroid drugs, immunosuppressants, and medications for diabetes and high blood pressure [1.2.3, 1.5.4]. Because of these risks, it is imperative to have a conversation with a healthcare provider or pharmacist before adding ashwagandha to your regimen. They can review your current medications and health conditions to help you avoid dangerous interactions and ensure your safety.
Authoritative Link: Ashwagandha: Usefulness and Safety | NCCIH
