What is Motrin PM (diphenhydramine and ibuprofen)? Diphenhydramine is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Antihistamines can cause drowsiness, which can aid in the treatment of occasional sleep problems (insomnia).
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). Ibuprofen works by reducing hormones that cause inflammation and pain in the body. Diphenhydramine and ibuprofen is a combination medicine used to treat occasional insomnia associated with minor aches and pains.