Doxylamine is a sedating antihistamine used to treat insomnia and allergic symptoms. In combination with pyridoxine (vitamin B6), it is also used to treat morning sickness in pregnant women. It is also used in nighttime cold medications and in pain medications containing acetaminophen and codeine to aid sleep. The drug is available over the counter and is taken perorally.
Doxylamine is a first-generation antihistamine and was first synthesized in 1948 by Nathan Sperber and colleagues in the United States.