Which supplement is commonly associated with many drug interactions and is often advised to consult a clinician before use?

• A. Garlic
• B. Ginkgo biloba
• C. Echinacea
• D. St. John’s wort

Answer: (D)

St. John’s wort is widely known for drug interactions because it activates the body’s drug-metabolizing systems, especially the enzyme CYP3A4 and the P-glycoprotein transporter. When these pathways are induced, many medications are broken down faster, lowering their blood levels and reducing their effectiveness. That’s why clinicians often caution patients to consult before using this supplement, particularly if they are taking prescription medicines. For example, it can shorten the effectiveness of birth control pills, certain antidepressants, and anticoagulants like warfarin, and it can lower levels of immunosuppressants and some HIV medications, which can have serious consequences. It can also interact with other drugs in ways that raise the risk of adverse effects, such as with serotonergic medications where there’s a potential for serotonin syndrome. Because of these widespread interactions, it’s important to review all medications with a clinician before starting St. John’s wort.