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When Foods Affect Medications 

What Type Of Food?

Your medication label may say take with food, but does the type of food you take it with matter? In many cases, the answer is no. Anything from a few saltines to a four-course dinner is fine. But in other cases the particular food is a factor. That’s because certain foods can affect the way your medications work.  

Careful With That Grapefruit

One of the most common examples of a problematic food when it comes to medications is grapefruit. Grapefruit contains substances that block the action of an enzyme called CYP3A4 involved in the breakdown of certain drugs in the small intestine. Eating grapefruit or drinking grapefruit juice along with one of these drugs can cause more of the drug to enter the bloodstream. The result can be equivalent to a drug overdose. Drugs affected include some immunosuppressive drugs such cyclosporine (Sandimmune and Neoral) used to treat lupus and prevent organ transplant rejection; some statin drugs used for high blood pressure including simvastatin (Zocor), atorvastatin (Lipitor) and prevastatin (Pravachol) ; and some anti-arrhythmia drugs such as amidarone (Cordarone and Nexterone). 

Other Problematic Foods

Other foods can block the actions of certain medications and deprive you of their full effects. For example, dairy foods can block the effects of iron supplements and many antibiotics as well as penicillamine (Cuprimine and Depen), a drug used to treat rheumatoid arthritis. Foods rich in vitamin K, including leafy green vegetables, can block the effects of blood thinners including warfarin (Coumadin). Oatmeal and other high-fiber foods can block the effects of digoxin (Lanoxin and Cardoxin), a drug prescribed for congestive heart failure. 
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Avoiding, Not Abstaining

There are many foods with the potential to interact with medications. The information you receive with your prescription will tell you if there are certain foods you should avoid while taking it. And what if your favorite food happens to be on the list? Take heart. Avoiding foods while taking medications doesn’t necessarily mean avoiding the foods altogether. Waiting until 3 hours after your last dose of medication – and at least three hours before your next one – is usually sufficient, but ask your pharmacist. 

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