Virginia Division of Forensic Science
Frequently Asked Questions
Questions
- What does it mean when the report indicate that no drugs are detected?
- How long after last use are drugs detectable?
Answers
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What does it mean when the report indicate that no drugs are detected?
There are no all-inclusive drug tests. Only specific drugs or drug categories may be addressed by any test or series of test. When the toxicology report indicates that no drugs were detected, this merely indicates that none in the specific categories mentioned were found at or above detection limits. Lower drug concentrations cannot be excluded. Further it does not exclude the presence of drugs in categories not tested.
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How long after last use are drugs detectable?
The answer depends on the drug, the sample tested and the sensitivity of the testing procedure. Generally most drugs are not detectable in blood after six to 48 hours, depending on the drug. Urine may allow detection for several days, sometimes even more than a week. However urine analysis does not generally permit any toxicological evaluation of drug impairment, merely drug use.