Drug abuse is the use or overuse of any drug in a manner that deviates from the prescribed pattern of use. It is usually self-administered. House is known for abusing Vicodin
Drug abuse is a frequent differential on the show, and is usually Chase's "go to" diagnosis. However, although the patient has abused drugs in several episodes of the show, it is rarely if ever the correct diagnosis (the primary exception being Control, where the patient abused an emetic as part of her bulimia).
However, as House has pointed out, even drug abusers get sick. This was never proved more clearly than in the episode Games where the patient, a habitual abuser of illegal drugs and nicotine, actually had an atypical presentation of measles.
The societal response to drug abuse was discussed in the Michael Tritter story arc, when it was discussed whether House's drug problems should be dealt with by doctors, with rehab, or within the criminal justice system. However, all of these approaches have problems. Given the current state of drug enforcement in the United States, it is difficult or impossible for a physician to prescribe large amounts of narcotics to a patient, even if there appears to be a therapeutic need for those drugs. For example, it is often difficult to determine whether House's need for Vicodin is due to an addiction or the very real chronic pain in his right leg.
Although rehab has shown promise, the vast majority of drug abusers (including alcoholics) will suffer some sort of relapse before permanently giving up the drug. Complicating the process is that the symptoms of withdrawal from a drug can occasionally be more dangerous than the continued use of the drug.