Final answer:
Codeine acts as an antitussive, which suppresses coughing by affecting the brain. It is no longer recommended for children. There are other cough suppressants like DXM, but codeine's efficacy is under scrutiny.
Step-by-step explanation:
The action of codeine when used to treat a cough is as an antitussive. Codeine works by decreasing activity in the part of the brain that causes coughing. Although codeine was once viewed as the "gold standard" in cough suppressants, its efficacy, especially in children, has been questioned in recent years. It is no longer recommended for children because of the lack of evidence showing its effect and concerns of harm, such as breathing problems. Furthermore, other cough treatments, such as expectorants and decongestants, are not highly effective in viral upper respiratory infections.
Hydrocodone, which is similar to codeine, is also classified as an antitussive and is used to relieve cough by affecting the brain and nervous system. Conversely, substances like DXM (Dextromethorphan) are also cough suppressants found in over-the-counter medications, which can be abused if not used responsibly. It is important to note that each substance has different applications depending on its properties and the type of cough symptoms presented.