People’s Pharmacy: Did antihistamine increase risk of dementia?

Q. Both my mother and mother-in-law were diagnosed with Alzheimer’s disease. Mom was 76, and my mother-in-law was 72.

They lived very different lifestyles: Mom dealt with severe anxiety and depression, while my mother-in-law was a happy-go-lucky, active and vivacious health nut. The only common denominator they shared is that they both took diphenhydramine to sleep. Their doctors advised this!

Recently, an older friend at church said her doctor had advised her to do the same. I cautioned her against it.

Of course, our mothers might have developed Alzheimer’s regardless. I do believe diphenhydramine exacerbated the tendency. We must be our own health care advocates and watch out for our elderly loved ones as well.

A. Diphenhydramine (Benadryl) is an old-fashioned antihistamine that was originally developed to treat allergies. Because it often makes people drowsy, drug companies have added diphenhydramine to over-the-counter sleeping pills. Virtually all “PM” nighttime pain relievers contain this drug.

Diphenhydramine is an anticholinergic medicine because it interferes with the action of the brain chemical acetylcholine. Long-term use of strong anticholinergic drugs has been linked to the risk of dementia (BMJ, April 25, 2018). A review of sleep medicines in older adults concluded that “Diphenhydramine should be avoided in the elderly” (Clinical Therapeutics, November 2016).

Q. My ophthalmologist recommended fish oil capsules, but I noticed no benefit from a 2,400 mg daily dose. However, a second ophthalmologist said that my eyes would be the last organ to receive the oil. She suggested I try increasing the dose if I could tolerate it.

I gradually went up to three 2,400 mg capsules. I have now gone from using eyedrops about 20 times a day to five or six times a day. As a retired statistician, I can assure you that is a statistically significant difference!

A. A study in the New England Journal of Medicine (April 13, 2018) found that 3,000 mg of fish oil was no better than placebo for alleviating dry eye symptoms. That said, your experience sounds compelling. Many other readers also believe fish oil helps their dry eyes. One wrote: “Fish oil most definitely helps my dry eye problem. As soon as I started taking 2,000 mg a day, I could tell a difference. If I go off it, my eyes are dry within a couple of days. The brand matters.”

Q. I use over-the-counter athlete’s foot cream from the dollar store as an overnight remedy for cracks in the corners of my mouth. I finally figured this out for myself after many years of relying upon lip balm alone.

A. You are describing angular cheilitis (aka perleche). It is sometimes caused by moisture trapped in the corners of the mouth. This can lead to an overgrowth of fungus. That’s why an antifungal cream for athlete’s foot sometimes can help this condition.

This painful and unsightly condition also can be caused by nutritional deficiencies. You should be checked to see whether you are getting enough B vitamins, iron and zinc.