Promethazine hydrochloride Phenergan is a medication commonly used to treat allergies, nausea, and sleep disorders. It is included to a class of drugs known as first-generation antihistamines. Popular brands Phenergan, Avomine or Sominex. (tablets, syrup, capsules or suppositories). Uses of Promethazine Allergy Relief: Promethazine helps reduce symptoms such as sneezing, runny nose, and itching caused…