Well....not inhibits, but supresses. I know this sounds like we are splitting hairs, but there are times when a patient has a productive cough, which means there are secretions which need to be removed yet the patient has gotten to the point of cyclic coughing, which makes their cough more shallow. So, if we can calm that cyclic cough, each cough comes from a lower area in the lungs and moves more secretions up (allowing better oxygenation lower). In a more extreme example, a narcotic (usually codeine, but there are others used - ie Robitussin AC) is used to actually give rest because the patient is too fatigued to actually cough, even though the fluid is loose enough to do so. Think about when you've had a very bad URI - when you went to sleep, you knew you would cough, but you didn't want to cough every hour. When they come and ask your advice, you'll hear symptoms like this - I cough so much I can't sleep (after you've ascertained their cough is productive) Now...if the patient has a nonproductive cyclic cough (a dry cough) I'll advise dextromethophan alone - no need for the guiafenesin (although it won't hurt and is often less expensive).
