Hydrocodone is a narcotic analgesic agent used to relieve severe pain. It is effective for the treatment of moderate to moderately severe pain and is as effective as codeine for cough suppression and nearly equipotent to morphine for pain relief. Hydrocodone is the most frequently prescribed opioid in the United States, and it is associated with more drug abuse and diversion than any other licit or illicit opioid. Hydrocodone primarily binds and activates the mu-opioid receptor in the central nervous system (CNS) and possesses analgesic and antitussive effects. It is also an antitussive (cough suppressant) agent with an efficacy similar to that of codeine. Hydrocodone is available in combination with other medications, such as acetaminophen, ibuprofen, and antihistamines. It is important to note that hydrocodone can be habit-forming and can cause mental or physical dependence if used for a long time. Therefore, it should only be used to treat people who are expected to need medication to relieve severe pain around-the-clock for a long time and who cannot be treated with other medications or treatments.