Robitussin Adult Long-Acting CoughGels provide up to eight hours of cough relief in a single dose. The convenient liquid filled capsules make this cold and cough medicine perfect for at home or on the go. For adults and children 12 years and older, take two capsules every six to eight hours as needed for symptom relief. Robitussin long-acting CoughGels contain dextromethorphan, a tough cough suppressant that helps reduce the urge to cough and provides dry cough relief. This daytime cough medicine relieves symptoms while letting you get on with your day. Delivering trusted and effective cough relief for more than 75 years, Robitussin has the product you need to treat your specific cough or flu symptoms. Robitussin shuts coughs down.