The drug of abuse test is a painless urine test that analyzes your urine for the presence of certain illicit drugs and prescription medicines. This test helps your doctor to detect the presence of illegal drugs like marijuana, cocaine, methamphetamines, opioids, etc in your body. Constant exposure to such drugs can lead to serious effects like mood swings, depression, anxiety, unplanned risky behaviour and there is always a risk of drug overdose. Drug rehabilitation centers test their patients on a regular basis to ensure that people receiving treatment for drug abuse stay sober.