Phenergan, also called Promethazine, is a Phenothiazine-derivative antihistamine used to relieve or prevent the symptoms of hay fever and other types of allergy. They work by preventing the effects of a substance called histamine that can cause itching, sneezing, runny nose, and watery eyes. Some antihistamines are also used to prevent motion sickness, nausea, vomiting, and dizziness, or to help people go to sleep and control anxiety before or after surgery.
Be sure to tell your doctor of any allergies you have whether it is to medication or food, preservatives, or dyes. Tell your doctor immediately if you are, or become pregnant, or are breastfeeding. Also, tell your doctor of any other medications you are taking, including vitamins and supplements, and any medical conditions you may have.
It is very important that you take this medicine exactly as your doctor tells you to. If you miss a dose of this medicine, take it as soon as you remember, unless it is almost time for your next dose. Do NOT double doses.
Tell your doctor as soon as possible if any of the following side effects occur: sore throat and fever; unusual bleeding or bruising; or unusual tiredness or weakness.
Promethazine hydrochloride is a racemic compound; the empirical formula is C17H20N2S•HCl and its molecular weight is 320.88. Promethazine hydrochloride occurs as a white to faint yellow, practically odorless, crystalline powder which slowly oxidizes and turns blue on prolonged exposure to air. It is soluble in water and freely soluble in alcohol. Injection: Each ml of the Tubex and Tubex Blunt Pointe Sterile Cartridge Units contains either 25 or 50 mg promethazine hydrochloride with 0.1 mg edetate disodium, 0.04 mg calcium chloride, not more than 5 mg monothioglycerol and 5 mg phenol with sodium acetate-acetic acid buffer. Sealed under nitrogen. Syrup: Each teaspoon (5 ml) of Phenergan Syrup Plain contains 6.25 mg promethazine hydrochloride in a flavored syrup base with a pH between 4.7 and 5.2. Alcohol 7%. The inactive ingredients present are artificial and natural flavors, citric acid, D&C Red 33, D&C Yellow 10, FD&C Blue 1, FD&C Yellow 6, glycerin, saccharin sodium, sodium benzoate, sodium citrate, sodium propionate, water, and other ingredients. Tablets and Suppositories: Each tablet of Phenergan contains 12.5 mg, 25 mg, or 50 mg promethazine hydrochloride. The inactive ingredients present are lactose, magnesium stearate, and methylcellulose. Each dosage strength also contains the following: 12.5 mg¾FD&C Yellow 6 and saccharin sodium; 25 mg¾saccharin sodium; 50 mg¾FD&C Red 40.
Each rectal suppository of Phenergan contains 12.5 mg, 25 mg, or 50 mg promethazine hydrochloride with ascorbyl palmitate, silicon dioxide, white wax, and cocoa butter. Phenergan Suppositories are for rectal administration only.
Phenergan has the following structural formula: