Benylin Dry Coughs Original Benylin Dry Coughs Original helps to relieve dry, irritating coughs. The liquid contains three active ingredients: Diphenhydramine hydrochloride: an antihistamine that helps relieve coughing & dry secretions in the nose & chest. Dextromethorphan hydrobromide: helps you stop coughing. Levomenthol: helps you breathe more easily by relieving congestion. Benylin Dry Coughs Original is suitable for adults & children aged 12 years & over.