Doxylamine has different uses in over-the-counter (OTC) medicines. Doxylamine is an antihistamine, which means it can be used to treat the symptoms of hay fever and other respiratory allergies. In a higher dose, doxylamine can be used to help with occasional sleeplessness. It may be written as doxylamine or doxylamine succinate, but it is the same active ingredient. Doxylamine can be found in multi-symptom relief or combination cough, cold, and flu remedies. It is also available as a single ingredient in nighttime sleep-aid medicines.
Doxylamine is approved by the U.S. Food and Drug Administration (FDA) and is safe and effective when used according to the Drug Facts label. While doxylamine may be used in products that treat cold symptoms as well as sleeplessness, the dosing frequency and directions differ between cold medicines and sleep aids. To ensure proper use, do not take a nighttime sleep-aid medicine to treat allergies or cold symptoms or an allergy or cold medicine to relieve sleeplessness.