Which substance is commonly used as an antitussive?

Codeine is commonly used as an antitussive, which means it is specifically indicated for the treatment of cough. It works by suppressing the cough reflex in the brain, providing relief from coughing associated with various respiratory conditions. Codeine's effectiveness in controlling cough makes it a preferred choice among healthcare providers for this purpose, especially in cases where a persistent or severe cough disrupts patient comfort or sleep.

Other substances listed, such as hydromorphone, morphine, and oxycodone, are primarily classified as analgesics, used for pain relief rather than for suppressing cough. While they may exhibit some cough-suppressing properties due to their opioid nature, they are not typically prescribed specifically as antitussives. Their main usage focuses on managing pain, and their higher potential for side effects and dependency makes them less suitable for treating cough compared to codeine.