A note was posted previously concerning the use of benadryl(diphenhydramine)
for colic.

The pediatricians in my department seldom if ever treat colic with
medications,  instead opting to comfort the parent, maybe discern if food
allergies exist,  and maybe a slight change in diet if possible.  But they
almost never use medications.   Never opiates,  and only occassionally other
anticholinergics (dicyclomine-Bentyl drops).  But again,  almost never.

I suppose Benadryl might be slightly effective, either because of its
sedative effect, or its anticholinergic effect,  but I don't know anyone
that uses it.   I would warn against continuous use over several days.
Benadryl seems to accumulate in infants and older children,  producing
hallucinations.  I've personally seen it in an 8 year old with chickenpox
after 2 days of use(snakes on the bed).  Its a well known side effect,  not
really dangerous,  but interesting.

TWHale