Promethazine Hydrochloride Injection 25 mg/mL x 25 Ampules By Xgen Pharma (RX)Promethazine Hydrochloride Injection 25 mg mL ampules are used for the treatment of allergy symptoms, such as rash, itching, and runny nose, as well as for the prevention and treatment of nausea and vomiting. Additionally, they can be used as a sedative or sleep aid before and after surgery. Promethazine, an antihistamine, works by blocking histamine receptors, thus reducing allergic reactions and motion sickness symptoms. It also impacts the brain's