When codeine is used to reduce coughing, it works by decreasing the activity in the part of the brain that causes coughing. Codeine is also available in combination with acetaminophen and aspirin, and as an ingredient in many cough and cold medications. 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. Codeine is an opioid, and its cough-suppressing effect works primarily through the brain rather than the throat or lungs. The drug activates mu-opioid receptors in the central nervous system, which dampens the cough reflex at its source in the brainstem. Codeine-containing cough medicines should not be used in children under 12 years of age due to safety concerns, and adults should use no more than 30-60 mg every 4 hours, not exceeding 6 doses in 24 hours. Codeine is an oral prescription opioid (narcotic) drug most commonly used to treat mild-to-moderate pain, as a cough suppressant, and to help relieve pain from tension headaches. Because codeine is not only ineffective but also frequently associated with gastrointestinal symptoms, the use of codeine as a cough suppressant should be discouraged and acknowledged as a prevalent medical myth. What is codeine and guaifenesin? Codeine is a narcotic cough suppressant. It affects the signals in the brain that trigger cough reflex. Guaifenesin is an expectorant. It helps loosen congestion in your chest and throat, making it easier to cough out through your mouth. Codeine treats pain and coughs but comes with real risks. Learn how it works, its side effects, and why doctors are prescribing it less often. Codeine is effective for cough suppression, particularly in patients with chronic bronchitis, as it works as an antitussive medication by directly suppressing the cough center in the brain's medulla, reducing the urge to cough. 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.