The analgesic actions of codeine derive from its conversion to morphine by the CYP450 2D6 enzyme system, whereas the drug’s antitussive effects are due to codeine itself. Thus, codeine is a much less potent analgesic than morphine. Codeine’s analgesic potency is approximately 30 percent that of morphine. Codeine shows good antitussive activity at doses that do not cause analgesia. At commonly used doses, the drug has a lower potential for abuse than morphine. Codeine is often used in combination with aspirin or acetaminophen. In most nonprescription cough preparations, codeine has been replaced by drugs such as dextromethorphan, a synthetic cough depressant that has relatively no analgesic action and a relatively low potential for abuse in usual antitussive doses.