Chemists Own Antihistamine for Allergy Relief contains the antihistamine Promethazine Hydrochloride used to treat several different conditions, including but to limited to: Allergies: hayfever symptoms, allergic rhinitis, allergic or itchy skin conditions such as contact ...Chemists Own Antihistamine for Allergy Relief contains the antihistamine Promethazine Hydrochloride used to treat several different conditions, including but to limited to: Allergies: hayfever symptoms, allergic rhinitis, allergic or itchy skin conditions such as contact dermatitis or hives Allergic reactions to bites or stings Prevention and treatment of travel sickness Nausea and vomiting Sedation for short-term use under the advice of a doctor or pharmacist.