Promethazine HCl generic or brand is an injectable drug administered by a doctor deep into a muscle for the treatment of motion sickness, to control nausea and vomiting caused by certain anesthetics and surgeries, to control post-operative pain, sedation pre/post-operative and during labor, and for anaphylaxis as an adjunct to epinephrine. Be certain your doctor is aware of all current meds you are taking and any allergies you have that could cause an adverse drug reaction with Promethazine HCl. The generic alternative is not manufactured by the company that makes the brand product.