Dr Amir Khan, a TV doctor known for appearances on This Morning and Lorraine, has issued an urgent warning for people taking certain medications, including warfarin, tetracyclines, ciprofloxacin and some statins. He cautioned that common supplements can interfere with how these drugs work, potentially causing serious health risks.
Speaking on Instagram, Dr Khan highlighted St. John's wort as a major culprit, noting it can interfere with antidepressants, the contraceptive pill, blood thinners and post-transplant medications. He also warned that turmeric or curcumin supplements, popular for inflammation and joint pain, may increase bleeding risk when taken with blood thinners like warfarin.
Magnesium supplements can affect the absorption of antibiotics such as tetracyclines and fluoroquinolones (e.g., ciprofloxacin, levofloxacin), as well as thyroid medication like levothyroxine. Experts advise leaving at least four hours between taking levothyroxine and magnesium, and taking antibiotics at least two hours before or four to six hours after magnesium.
Calcium supplements can reduce absorption of levothyroxine and some antibiotics, while vitamin K can interfere with warfarin's effect on bleeding and clotting risk. Even grapefruit juice can interact with some statins and other medications by affecting drug breakdown.
Dr Khan emphasised that supplements are not inherently bad, but urged anyone on regular medication to inform their doctor about all supplements they take. 'Sometimes the interaction we're worried about isn't between two medications. It can be between medicine and something you thought was harmless like a supplement,' he said.
