Method of action and examples of different types of over the counter cough medicines Group Mechanism of action Examples of proposed active ingredients Examples of relevant preparations Antitussives Centrally acting opioid derivates or peripherally acting agents5 Codeine, moguisteine Famel original cough syrup Dextromethorphan Benylin dry coughs, Robitussin dry cough Expectorants Increased bronchial mucus production, making secretions easier to remove through cough or ciliary transport6 Guaifenesin, ipecacuana Adult Meltus expectorant, Beechams VENO's expectorant, Benylin chesty coughs (non-drowsy), Benylin children's chesty coughs, Hill's balsam chesty cough liquid, Vicks vaposyrup for chesty coughs Mucolytics Decrease the viscosity of bronchial secretions, making them easier to clear through coughing7 Bromhexine hydrochloride Bisolvon linctus Antihistamine-decongestant combinations Combine histamine H1 receptor antagonists and  adrenoceptor agonists, which cause vasoconstriction of mucosal blood vessels8 Pseudoephedrine plus guaifenesin Sudafed expectorant, Robitussin chesty cough with congestion Other drug combinations Fixed drug combinations using different ingredients Dextromethorphan, ephedrine, doxylamine, paracetamol Vicks Medinite EM-Vier (containing extract of thyme, eucalyptus oil, and menthol) Minetten Antihistamines Histamine H1 receptor antagonists Loratadine Clarityn allergy syrup