If diphenhydramine is a sleeping pill and an antihistamine, then why is it safe to take daily for allergy but not when insomnia is the issue?

Good question. As long as you don't exceed the dose or frequency on the label - they are equally risky/safe. Perhaps the concern more with insomnia than allergy is that sleep is a combo of physical and behavioral causes while allergy is considered all physical. So, some may think you should 1st try good sleep habits/hygiene before pills. Also they may fear dependence more w/ insomnia. Sharp thinking!

Related Questions

Is it safe to take one 25mg Benadryl (diphenhydramine) capsule solely as a sleep aid? Insomnia for a week, taking a toll on my physical and emotional well being.

Yes . One week should be okay. As long as the package inserts are followed. In the long term you'll benefit most from educating yourself about proper sleep hygiene as opposed to a quick fix with pills. Read more...
Yes. Yes Benadryl (diphenhydramine) is considered relatively safe although it can cause dry eyes dry mouth and even constipation in some. Some people feel "wired" after Benadryl (diphenhydramine) but if that is not the case for you then you can usually take it safely. Read more...