Q: I love grapefruit, the whole fruit.  I used to eat it often, but I have gone without for several years now.  That is because I take simvastatin to lower my cholesterol.

I discussed my cravings with my heart doctor, and we reached a happy medium.  I can have half a grapefruit in the morning every five or six days.  I take my pill in the evening, and he figures 12 hours or so is a safe time spread between medication and fruit.

A: Your doctor is partially correct.  Grapefruit contains compounds that inhibit a crucial enzyme in the digestive tract that breaks down many medications, including simvastatin.  This means more medicine circulates in the body, increasing the risk for side effects.

When grapefruit  and simvastatin are taken together, blood levels of the drug increase by 260 percent (American Journal of Medicine, January 2016). When taken 12 hours apart, as your doctor recommends, blood levels go up by 90 percent.  Enjoying grapefruit once or twice a week probably won’t have a lasting effect.  Daily grapefruit, however, could cause trouble, since the grapefruit effect lasts at least 24 hours.

• by Joe and Teresa Graedon
• copyright The Seattle Times