A toxicology screen is a test that determines the approximate amount and type of legal or illegal drugs that you’ve taken. It may be used to screen for drug abuse, to monitor a substance abuse problem, or to evaluate drug intoxication or overdose. Toxicology screening can be done fairly quickly. The test is most often done using a urine or blood sample. In some cases, a sample of saliva or hair may be used. The results can show the presence of one specific drug or a variety of drugs at once. Further testing may be needed to determine the exact amount of a particular drug in the body and to confirm the results. Most toxicology screens provide limited information about how much or how often someone has taken a drug. The results of a toxicology screen are usually positive or negative. A positive test result means that a drug or multiple drugs are present in the body. Once your doctor identifies the presence of a drug by screening, a more specific test may be done that can show exactly how much of the drug is present.A toxicology screen is a test that determines the approximate amount and type of legal or illegal drugs that you’ve taken. It may be used to screen for drug abuse, to monitor a substance abuse problem, or to evaluate drug intoxication or overdose. Toxicology screening can be done fairly quickly. The test is most often done using a urine or blood sample. In some cases, a sample of saliva or hair may be used. The results can show the presence of one specific drug or a variety of drugs at once. Further testing may be needed to determine the exact amount of a particular drug in the body and to confirm the results. Most toxicology screens provide limited information about how much or how often someone has taken a drug. The results of a toxicology screen are usually positive or negative. A positive test result means that a drug or multiple drugs are present in the body. Once your doctor identifies the presence of a drug by screening, a more specific test may be done that can show exactly how much of the drug is present.