There are a number of reasons for the use of drug tests. Some drug tests are requested by doctors for medical reasons, others by employers to ensure that employees are not working while under the influence of drugs. Drugs can be detected by testing samples of urine, blood, and other bodily fluids, as well as hair. The following sections explain the various reasons for drug testing, and the types of drug testing methods.

Various means are used to test for the presence of drugs, most involving chemical analysis of urine, blood, hair, sweat, or saliva.

Testing for Medical Reasons

Under many different conditions a physician may need to determine whether a person is using illegal drugs and, if so, what kind. A physician needs this information before deciding how to diagnose and treat a patient. For example, a person showing...