There is little evidence that cough medicines help adults stop coughing.

For a dry, hacking cough, try a cough suppressant that contains dextromethorphan. Dextromethorphan can be purchased without a prescription (Robitussin-DM), or in combination with decongestants, antihistamines and pain relievers (Robitussin Cough and Cold Formula, Robitussin-CF). Many commercial cough and cold products contain dextromethorphan. Carefully follow the instructions on the label.

Dosing Dextromethorphan

Weight	Dose (every 6-8 hours)
110 lb (50 kg)	25 mg
132 lb-adult (60 kg)	30 mg