Understanding Ashwagandha and Its Effects
Ashwagandha (Withania somnifera) is an evergreen shrub used for centuries in traditional Ayurvedic medicine to help with stress, anxiety, and sleep [1.2.3, 1.2.5]. Its active compounds, called withanolides, are thought to be responsible for its therapeutic effects [1.9.2]. However, the same properties that make ashwagandha beneficial can also cause it to interfere with various prescription and over-the-counter medications [1.2.2]. The herb can enhance or counteract the effects of certain drugs, leading to potentially dangerous health outcomes [1.5.4]. It is essential to consult with a healthcare provider before adding ashwagandha to your regimen, especially if you are taking other medications [1.2.1].
Major Drug Classes to Avoid with Ashwagandha
Several categories of medications have known interactions with ashwagandha. The primary concern is that ashwagandha can amplify the effects of drugs with similar properties, such as sedatives, or interfere with the intended action of others, like immunosuppressants [1.2.3, 1.4.6].
Sedatives and CNS Depressants
Ashwagandha has natural sedative properties and can cause drowsiness, sleepiness, and slowed breathing [1.4.2, 1.4.6]. The botanical name, Withania somnifera, even translates to "sleep-inducer" [1.2.3]. When combined with other medications that depress the central nervous system (CNS), this effect can become dangerously potent, leading to excessive drowsiness and an increased risk of accidents [1.4.4, 1.4.5].
It is strongly advised to avoid taking ashwagandha with the following medications:
- Benzodiazepines: Drugs like alprazolam (Xanax®), clonazepam (Klonopin®), and diazepam (Valium®) are used for anxiety and can have their sedative effects amplified [1.4.1, 1.4.2].
- Sleep Medications: Combining with zolpidem (Ambien®) or zaleplon (Sonata®) can lead to excessive sedation [1.4.4].
- Barbiturates: Medications such as phenobarbital can have their CNS depressant effects dangerously increased [1.4.1].
- Opioid Pain Medications: Drugs like oxycodone also have sedative properties that can be enhanced by ashwagandha [1.2.1].
- Anticonvulsants: Due to its GABAnergic effects, ashwagandha should likely be avoided with anticonvulsants [1.9.2].
Immunosuppressants
Ashwagandha may increase the activity of the immune system [1.5.3]. This directly contradicts the purpose of immunosuppressant drugs, which are prescribed to suppress an overactive immune system, often after an organ transplant or for autoimmune conditions like rheumatoid arthritis or lupus [1.5.2, 1.5.3]. Taking ashwagandha could potentially reduce the effectiveness of these critical medications, increasing the risk of organ transplant rejection or a flare-up of autoimmune symptoms [1.5.2, 1.9.2].
Examples of immunosuppressants include:
- Corticosteroids like prednisone [1.2.3].
- Organ transplant medications such as tacrolimus (Prograf®) and azathioprine (Imuran®) [1.2.3].
- Biologics like adalimumab (Humira®) [1.4.4].
Thyroid Medications
Studies show that ashwagandha can increase the body's natural production of thyroid hormones, specifically T3 (triiodothyronine) and T4 (thyroxine) [1.6.2, 1.6.5]. For individuals taking thyroid hormone replacement therapy for hypothyroidism (underactive thyroid), such as levothyroxine (Synthroid®), this can lead to an excess of thyroid hormones in the body (thyrotoxicosis) [1.6.3]. Symptoms can include a rapid heartbeat, anxiety, nervousness, and trouble sleeping [1.6.2]. Conversely, for those on antithyroid drugs like methimazole for hyperthyroidism (overactive thyroid), ashwagandha could interfere with treatment [1.6.4].
Diabetes Medications
Ashwagandha may lower blood sugar levels [1.7.2]. While this might sound beneficial, it poses a risk for individuals taking antidiabetic medications. The combined effect can cause blood sugar to drop too low, a condition known as hypoglycemia [1.7.3]. Symptoms of hypoglycemia include dizziness, confusion, weakness, and sweating [1.7.1]. It is crucial to monitor blood sugar levels closely if taking ashwagandha alongside diabetes medications like insulin, metformin, or glipizide (Glucotrol XL) [1.7.1, 1.7.2].
Blood Pressure Medications
Similar to its effect on blood sugar, ashwagandha may also lower blood pressure [1.8.3]. When taken with antihypertensive drugs, this can lead to hypotension, where blood pressure drops to dangerously low levels [1.8.4]. This can cause dizziness, lightheadedness, and fainting [1.8.2]. Caution is advised if you take medications such as ACE inhibitors (lisinopril), beta-blockers (atenolol), calcium channel blockers (amlodipine), or diuretics (furosemide) [1.2.3, 1.8.2].
Comparison of Ashwagandha Drug Interactions
| Medication Class | Example Drugs | Potential Interaction with Ashwagandha |
|---|---|---|
| Sedatives / CNS Depressants | Xanax®, Klonopin®, Ambien® | Increased drowsiness, sedation, and slowed breathing [1.4.1, 1.4.6]. |
| Immunosuppressants | Prednisone, Tacrolimus (Prograf®) | May decrease the effectiveness of the medication by boosting the immune system [1.5.3]. |
| Thyroid Medications | Levothyroxine (Synthroid®), Methimazole | May increase thyroid hormone levels, leading to thyrotoxicosis or interfering with treatment [1.6.2, 1.6.4]. |
| Diabetes Medications | Insulin, Metformin | Additive effect may cause blood sugar to drop too low (hypoglycemia) [1.7.2, 1.7.3]. |
| Blood Pressure Medications | Lisinopril, Amlodipine (Norvasc®) | Additive effect may cause blood pressure to drop too low (hypotension) [1.8.2, 1.8.3]. |
| Hepatotoxic Drugs | Indomethacin, Phenytoin | May increase the risk of liver damage [1.4.2, 1.4.6]. |
Other Important Considerations
- Antidepressants: The interaction between ashwagandha and antidepressants like SSRIs (e.g., Zoloft®, Lexapro®) is not well-studied. There is a theoretical risk of serotonin levels becoming too high, potentially leading to serotonin syndrome [1.2.3].
- Surgery: It is recommended to stop taking ashwagandha at least two weeks before a scheduled surgery. Its sedative effects could interfere with anesthesia and other medications used during and after the procedure [1.9.5].
- Pregnancy and Breastfeeding: Ashwagandha is considered unsafe during pregnancy as it may cause miscarriages. Its safety during breastfeeding is not known, so it is best to avoid it [1.9.5].
- Liver Health: In rare cases, ashwagandha has been linked to liver problems [1.9.5]. Combining it with other medications that can potentially harm the liver (hepatotoxic drugs) could increase this risk [1.4.2].
Conclusion
While ashwagandha is a popular herbal supplement with several potential health benefits, it is not without risks, particularly when it comes to drug interactions. The herb's ability to affect the central nervous system, immune system, thyroid hormones, blood sugar, and blood pressure means it can interfere with many common medications. Always consult a healthcare professional before taking ashwagandha to review your current medications and health conditions to ensure it is a safe option for you.
For more information on supplement interactions, an authoritative resource is the National Center for Complementary and Integrative Health (NCCIH): https://www.nccih.nih.gov/health/know-science/how-medications-and-supplements-can-interact
