Abuse means using a drug, alcohol or other substance in a way not intended by its manufacturers. For example, people can abuse paint thinner by breathing in the fumes to get high. People abuse painkillers when they take them for non-medical reasons. People abuse alcohol when they drink excessively or for the sole purpose of getting drunk. Physicians have a medical definition of abuse that they use when they diagnose addictions. They divide the misuse of substances into two categories: substance abuse and substance dependency. In order to be diagnosed with substance abuse, a patient must have at least one of the following symptoms over a one-year period: The substance use results in a failure to fulfil work, school or home obligations; the substance use results in situations that are physically dangerous, such as drunk driving; the substance use precipitates legal problems; the person keeps using the substance even though he or she is experiencing social or interpersonal problems because of its use. The criteria for substance dependency are similar, but also include physical symptoms such as an increased ability to tolerate higher amounts of the substance and experiencing withdrawal symptoms when use is stopped.