Abstract
Promethazine, a sedating antihistamine, is widely and increasingly prescribed for patients reporting problems sleeping. In this Against the Stream article, the case is made that promethazine is not suitable as a sleep aid for people using mental health services, because it has no good evidence base, impedes with psychological and behavioural techniques that do improve sleep in the medium-long term, has underappreciated addictive and recreational-use potential, and an unacceptable side-effect profile. Alternatives to promethazine are described, notably the NICE first-line recommendation, cognitive-behavioural therapy for insomnia.