Dear Dr. Roach: I read your recent column on the effects of Sudafed in older men. I am a 67-year-old male in good health, except for high cholesterol (controlled by medication) and a high PSA number. A couple of biopsies showed no sign of cancer. I’ve taken Benadryl on a daily basis for three or four years now. Does it have the same kind of long-term danger as Sudafed? Also, would this have anything to do with the PSA reading? — W.N.

Answer: Diphenhydramine (Benadryl, many others, and in many combination cold formulations as well as most sleeping medications) is an antihistamine that can affect urination. It does so not by affecting the prostate, but by reducing the bladder’s ability to contract. My experience has been that this effect is generally mild for most men, and if you have been taking Benadryl for years, it’s not likely to suddenly start bothering you. Pseudoephedrine, by contrast, has caused voiding dysfunction that put many older male patients in the ER, unable to urinate at all, after one dose.

If you are taking Benadryl every day for allergy symptoms, you could consider a newer antihistamine, such as loratadine (Claritin) or cetirizine (Zyrtec). Benadryl makes many people sleepy, and it increases risk of falls and car crashes, especially in older people. If you are taking it every day to help you sleep, I’d recommend trying to get off it for the same reasons. There has been some suggestion that daily Benadryl increases risk of dementia, but I am unconvinced so far by the evidence.

Benadryl has no effect on PSA level, as far as I could find.