how much diphenhydramine can you take at once?
Hay fever and allergies - diphenhydramine comes as 25mg and 50mg tablets. The usual dose is 25mg or 50mg, taken 3 or 4 times a day. Try to space your doses evenly throughout the day. Insect bites, stings and eczema - diphenhydramine comes as a cream which you use once or twice a day.