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A toxicology test ("tox screen") checks for drugs or other chemicals in your blood, urine, or saliva. Drugs can be swallowed, inhaled, injected, or absorbed through the skin or a mucous membrane. In rare cases, a tox screen may check your stomach contents or sweat.
A tox screen may check for one certain drug or for up to 30 different drugs at once. These may include prescription medicines, non-prescription medicines (such as aspirin), natural health products, alcohol, and illegal drugs, such as cocaine and heroin.
Testing is often done on urine or saliva instead of blood. Many drugs will show up in a urine or saliva sample. And urine and saliva tests are usually easier to do than blood tests.
This test may be done to:
Many medicines can change the results of this test. So give your doctor a list of all the medicines you have taken in the past 4 days. Be sure to include any prescription and over-the-counter medicines and natural health products.
A health professional uses a needle to take a blood sample, usually from the arm.
You may be asked to collect a clean-catch midstream urine sample for testing.
If you are being tested for drug use, a trained person of the same sex may watch you give the sample. This is to make sure that you are providing your own urine and that you have not added anything to the sample. The temperature of the urine may also be tested to make sure that it is fresh.
The person who collects the sample will either:
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
It is not painful to collect a urine sample. Another person may watch while you collect the sample. This may make you feel uncomfortable.
It is not painful to collect a saliva sample. Another person will collect the sample or watch you collect the sample.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
There are no known risks from having this test.
Most tox screens are qualitative tests. This means they only find out if drugs are present in the body, not the exact level or quantity. Follow-up quantitative testing is often done to find the level of a drug in the body and to confirm the results of the first test.
No unexpected drugs are found in the sample.
Levels of prescription or non-prescription medicines found in the sample are within the effective (therapeutic) range.
Unexpected drugs are found in the sample.
Levels of prescription or non-prescription medicines found in the sample are:
High levels may be caused by a drug overdose, either by mistake or on purpose. A drug overdose may be caused by one large dose of medicine or long-term overuse of a medicine.
Interactions between medicines also can cause problems, especially when you start to take a new medicine. A high level may mean that you are not taking your medicine correctly or that your body is not processing the medicine as it should.
Low levels of prescription or over-the-counter medicines may tell your doctor you are not in an effective (therapeutic) range.
Current as of: March 22, 2023
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineMartin J. Gabica MD - Family MedicineKathleen Romito MD - Family MedicineR. Steven Tharratt MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
Current as of: March 22, 2023
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Martin J. Gabica MD - Family Medicine & Kathleen Romito MD - Family Medicine & R. Steven Tharratt MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
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