Benylin 4 Flu Liquid Benylin 4 Flu Liquid helps to relieve the symptoms of cold & flu in adults & children over 12 years. It contains: Paracetamol: an analgesic which helps to relieve aches & pains & fever (high temperature). Diphenhydramine: an antihistamine which helps dry secretions & relieve coughing. Pseudoephedrine: a decongestant which helps unblock stuffy noses. Benylin 4 Flu Liquid comes with a measuring cup for easy & accurate dosing.