benadryl and possible erection problems

Hi,

    I have been taking 75 mg Benadryl every other night now for about 3-4 months.  I cant state a specific time but I have been noticing that I havent been getting as many morning erections and Ive been having a problem maintaining hard erections. Ive done some research on the net and have seen many sites saying that benadryl can cause impotence but they dont say why or how. Ive also seen a couple instances of people saying they have had this side effect. My situation is that benadryl is very cost effective for me and works wonders for my mild insomnia and nighttime allergies. It has been a godsend for me besides this impotence problem..  I just want to get some knowledgable insight to see if it is truly the benadryl effecting me.

1. Because benadryl is anticholinergic and effects urinary flow does that mean it effects the nerves or arteries that control an erection? Or is it the cns depressive effect that could effect an erection?
2. Is it true that all anticholinergic medicines by their default mechanism of action will effect erections?
3. Have you ever encountered any other instances of this with other patients?

[Kevin Pho, MD]

To answer your questions:
1) I am not sure of the exact mechanism why benadryl can cause impotence, however it is not uncommon that anticholinergic medications are associated with erectile dysfunction.  I do not believe that Benadryl has any effect on the penile vasculature.

2) Again, I cannot be 100% sure, but it is thought that yes, anticholinergics certainly can affect erections by their default mechanism of action.  

3) Yes, I have seen several cases where OTC antihistamines affect erections.

Followup with your personal physician is essential.

This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.

Kevin, M.D.
Medical Weblog:
kevinmd_b