Phenergan Night Time contains a medicine called promethazine hydrochloride and works by blocking a natural substance (histamine) that your body makes during an allergic reaction. It also works directly on the brain to help you feel more relaxed. Phenergan Night Time contains a medicine called promethazine hydrochloride. This belongs to a group of medicines called phenothiazines. It works by blocking a natural substance (histamine) that your body makes during an allergic reaction. It also works directly on the brain to help you feel more relaxed. What Phenergan Night Time is used for Phenergan Night Time is used to treat the following conditions: For short-term use: to treat adults with difficulty sleeping (insomnia) For short-term use: as a sedative for children aged 16 years and above What Phenergan Night Time looks like and the contents of the pack. A pale blue film-coated tablet marked PN 25 on one side. The tablets are available in blister packs of 14. Approved by Nicola Howson - A