I've broken out in what i think are hives on my legs. i had diarrhea earlier and i just dry heaved. so i want to know if i can take three benadryl (diphenhydramine)?

Yes: Read the label and know the potential adverse effects of Benadryl (diphenhydramine) before using. Recommend starting with 50mg dose and can repeat 3-4hrs later if needed. Hives in association with new diarrhea are almost certainly a result of the immune response to infection and should clear up shortly. If they return after Benadryl (diphenhydramine), consider longer acting, newer-generation antihistamine such as cetirizine.