Quickly soothes dry and irritating coughs. Bisoltussin Cough Dry works quickly, decreasing the urge to cough in about 15 to 30 minutes after taking it. Mode of action: Bisoltussin Tosse Seca is an antitussive medicine indicated for the symptomatic treatment of irritating and dry cough. The active substance in Bisoltussin Tosse Seca, dextromethorphan, works at the cough center, inhibiting it. This action results in the antitussive effect of the drug. The syrup has a pleasant taste and does not contain alcohol or sugar (it does not contain sucrose, lactose or fructose) and therefore can be taken by diabetics.