Promethazine is a first-generation antihistamine and antiemetic used to treat allergies, insomnia, and nausea. It may also help with some symptoms associated with the common cold and may also be used for sedating people who are agitated or anxious. Promethazine is available by mouth in syrup or tablet dosage forms, as a rectal suppository, or by injection into a muscle.Common side effects of promethazine include confusion and sleepiness; consumption of alcohol or other sedatives can make these symptoms worse. It is unclear if use of promethazine during pregnancy or breastfeeding is safe for the baby. Use of promethazine is not recommended in those less than two years old, due to potentially negative effects on breathing. Use of promethazine by injection into a vein is not recommended, due to potential skin damage. Promethazine is in the phenothiazine family of medications.Promethazine was made in the 1940s by a team of scientists from Rhône-Poulenc laboratories. It was approved for medical use in the United States in 1951. It is a generic medication and is available under many brand names globally. In 2019, it was the 174th most commonly prescribed medication in the United States, with more than 3 million prescriptions. Medical uses
Promethazine has a variety of medical uses, including:

Sedation
For nausea and vomiting associated with anesthesia or chemotherapy. It is commonly used postoperatively as an antiemetic. The antiemetic activity increases with increased dosing; however, side effects also increase, which often limits maximal dosing.
Society and culture
As of July 2017 it was marketed under many brand names worldwide: Allersoothe, Antiallersin, Anvomin, Atosil, Avomine, Closin N, Codopalm, Diphergan, Farganesse, Fenazil, Fenergan, Fenezal, Frinova, Hiberna, Histabil, Histaloc, Histantil, Histazin, Histazine, Histerzin, Lenazine, Lergigan, Nufapreg, Otosil, Pamergan, Pharmaniaga, Phenadoz, Phenerex, Phenergan, Phénergan, Pipolphen, Polfergan, Proazamine, Progene, Prohist, Promet, Prometal, Prometazin, Prometazina, Promethazin, Prométhazine, Promethazinum, Promethegan, Promezin, Proneurin, Prothazin, Prothiazine, Prozin, Pyrethia, Quitazine, Reactifargan, Receptozine, Romergan, Sominex, Sylomet, Xepagan, Zinmet, and Zoralix. It is also marketed in many combination drug formulations:

with carbocisteine as Actithiol Antihistaminico, Mucoease, Mucoprom, Mucotal Prometazine, and Rhinathiol;
with paracetamol (acetaminophen) as Algotropyl, Calmkid, Fevril, Phen Plus, and Velpro-P;
with paracetamol  and dextromethorphan as Choligrip na noc, Coldrex Nočná Liečba, Fedril Night Cold and Flu, Night Nurse, and Tachinotte;
with paracetamol, phenylephrine, and salicylamide as Flukit;
with dextromethorphan as Axcel Dextrozine and Hosedyl DM;
with dextromethorphan and ephedrine as Methorsedyl;
with dextromethorphan and pseudoephedrine as Sedilix-DM;
with dextromethorphan and phenylephedrine as Sedilix-RX;
with pholcodine as Codo-Q Junior and Tixylix;
with pholcodine and ephedrine as Phensedyl Dry Cough Linctus;
with pholcodine and phenylephedrine as Russedyl Compound Linctus;
with pholcodine and phenylpropanolamine as Triple P;
with codeine as Kefei and Procodin;
with codeine and ephedrine as Dhasedyl, Fendyl, and P.E.C. ;
with ephedrine  and dextromethorphan as Dhasedyl DM;
with glutamic acid as Psico-Soma, and Psicosoma;
with noscapine as Tussisedal; and
with chlorpromazine  and phenobarbital as Vegetamin. Recreational use
The recreational drug lean, also known as purple drank among other names, often contains a combination of promethazine with codeine-containing cold medication. Product liability lawsuit
In 2009, the US Supreme Court ruled on a product liability case involving promethazine.