How Do You Reduce Swelling From Poison Oak?

How Do You Reduce Swelling From Poison Oak? Oral antihistamines, such as diphenhydramine (Benadryl), may help reduce inflammation, itching, and rash. A pharmacist can advise on suitable options, as some types can cause drowsiness. How long does swelling from poison oak last? The reaction usually develops 12 to 48 hours after exposure and lasts two