Benzodiazepines and Diphenhydramine Hydrochloride

There is synergy, but I do not see a problem if you mix them in moderation. But the problem with that is benzo tolerance. Experiment with lower dosages (25-50mg) of the diphenhydramine first or talk to a pharmacist or physician.

Diphenhydramine is just Benadryl, and yes, you can take them together. Both will tend to make you sleepy, but if you're taking lorazepam regularly, at a reasonable dose, you should be acclimated to any sleepiness side effect, and not become any sleepier than a normal person just taking Benadryl. If you're not used to either drug, than I agree with the posts above that you might have a very sleepy day.

It will just make you more sleepy, but, I imagine if you're taking Advil PM it is because you want to sleep. Otherwise, no, there is no dangerous chemical reaction.

Taking both will sedate you seriously..you will be hung over when you DO wake up 15 hours after you take them.