Coricidin HBP Cough & Cold contains the antihistamine chlorpheniramine maleate and the cough suppressant dextromethorphan hydrobromide, according to its manufacturer Bayer. Coricidin HBP Cold & Flu's active ingredients are chlorpheniramine maleate and acetaminophen, which serves as a fever reducer and pain reliever.
Chlorpheniramine maleate works by blocking histamine, a natural substance the body releases due to an allergic reaction that occurs with some diseases, including the common cold, explains WebMD. It can treat runny noses and sneezing, and it can help people with rashes. It can also relieve itchiness of the eyes, skin, nose and throat.
Dextromethorphan is a cough suppressant, reports Drugs.com, and it works by affecting the part of the brain that controls the coughing reflex. However, it is not effective against coughing caused by asthma, emphysema or smoking. It can also interact with certain drugs, such as MAO inhibitors, and people should speak with a doctor or pharmacist before taking drugs containing dextromethorphan, especially if they are taking other drugs.
Acetaminophen is both a fever reducer and a pain reliever so it can treat multiple symptoms of the common cold, notes Drugs.com. It is also the active ingredient in Tylenol and other over-the-counter pain relievers. Because of its common use in over-the-counter drugs, it is important to be cautious when taking it to avoid an overdose from different drugs that contain acetaminophen as an active ingredient.