Learn about the side effects of Robitussin-AC (codeine/guaifenesin), from common to rare, for consumers and healthcare professionals. Codeine/guaifenesin is a cough syrup that contains an expectorant and an opioid. It's used to help loosen mucus and calm coughs in adults and older children. Codeine/guaifenesin is taken by mouth, typically every 4 hours as needed. Compare prices and print coupons for Robitussin AC and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $9.81. Robitussin (guaifenesin) is an expectorant. It helps loosen congestion in your chest and throat, making it easier to cough out through your mouth. Robitussin is used to reduce chest congestion caused by the common cold, infections, or allergies. Shut down your cough with Adult Robitussin Cough Relief products. Find out which Robitussin product is right for you by browsing our collection today. Robitussin Ac (Guaifenesin and Codeine) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources. Robitussin AC (generic codeine 10 mg and guaifenesin) is a prescription cough medicine that combines an opioid cough suppressant with an expectorant to relieve coughs and clear mucus from your airways. Overview: Codeine/guaifenesin is a combination medicine used to reduce coughing and loosen mucus from the common cold or allergies. It works by affecting the part of the brain that controls the. When you’re feeling under the weather looking for cold and flu medicine to relieve your symptoms, know that there’s a Robitussin product for you. Whether you need to get rid of a dry cough or alleviate a sinus headache, Robitussin products provide powerful relief. Codeine belongs to the group of medications called narcotic analgesics and cough suppressants. It works by blocking pain signals that are sent out by the brain to various areas of the body and reduces cough by acting in the brain to dull the cough reflex.