People’s pharmacy

Q: I’ve just been put on simvastatin to control my cholesterol. I’m also on amiodarone for my heart. I take blood pressure pills, an antidepressant and quite a few other medications, including warfarin, which is for my atrial fibrillation.

I had no idea that grapefruit juice wasn’t good if you’re on certain pills. I just read about this on your website. I drink loads of pink grapefruit juice. Could there be any problem with my medications?

A: Yikes! Almost all your medications interact dangerously with grapefruit juice (pink or white). The effects of simvastatin, amiodarone and warfarin could all be magnified by grapefruit (Evidence Based Complementary and Alternative Medicine online, March 18, 2014). Certain blood pressure pills (felodipine and similar drugs) and the antidepressant sertraline also interact with grapefruit (World Journal of Biological Psychiatry, Vol. 10, No. 4, Part 3, 2009).

Our free Guide to Grapefruit Interactions can be found at Ask your doctor whether there are noninteracting substitutes for your medications.

Q: I am phobic about ticks, having had Rocky Mountain spotted fever as a result of a tick bite. Is there any good way to keep them off me?

A: Spray a DEET-containing repellent around shoes, socks and ankles. You also may want to ask your pharmacist to order sulfur powder if she doesn’t already stock it. It can be dusted around shoes and ankles for extra protection.

Tuck the bottom of your pants legs into your socks to keep ticks off your shins. Even with these precautions, a few ticks may get past this barrier. Always check for ticks after being outside.

Q: I have severe osteoarthritis of the knee and used Celebrex, with fair results. My doctor then prescribed a compounded, topically applied medicine containing ketoprofen in a 20 percent gel. It has been very effective in relieving my knee pain, particularly at rest when the pain would “pulse” uncomfortably. The relief occurs around 20 minutes after applying the gel.

I was doubtful at first that any topically applied drug would help, but believe me, it really does. Why isn’t this treatment better known?

A: Topical NSAIDs (nonsteroidal anti-inflammatory drugs) such as ketoprofen and diclofenac (Pennsaid, Voltaren Gel) have been used successfully in Europe, Canada, Australia and New Zealand for years. Data from placebo-controlled trials show that topical NSAIDs are about as effective as oral NSAIDs in alleviating knee pain due to osteoarthritis (Journal of Family Practice, February 2015).

Although Voltaren Gel is available in some countries over the counter, in the U.S. it requires a prescription. To learn more about these medications and other options for managing joint pain, you may want to read our Guide to Alternatives for Arthritis. Anyone who would like a copy, please send $3 in check or money order with a long (No. 10), stamped (70 cents), self-addressed envelope to: Graedons’ People’s Pharmacy, No. AA-2, P.O. Box 52027, Durham, NC 27717-2027. It also can be downloaded for $2 from our website:

Side effects of diclofenac gel include dry skin or rash at the application site. Some people also experience digestive upset, although this is more common among people taking the oral medication. Topical ketoprofen can sometimes trigger an allergic reaction to sunlight (European Journal of Dermatology, May 2014).

Joe and Teresa Graedon answer letters from readers. You can email them via their website: Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”