Mepyramine

Mepyramine (INN, also known as pyrilamine) is a first generation antihistamine, targeting the H1 receptor. However, it rapidly permeates the brain and so often causes drowsiness as a side effect.

It is used in over-the-counter combination products for colds and menstrual symptoms.

Side effects may include sedation/drowsiness, muscle weakness, and insomnia.