What does a drug test show?
Which substances drug tests detect, how the results are presented, the difference between screening and confirmation — and what a positive or negative result actually means.
A drug test shows the presence or absence of specific substances or their metabolites in a biological sample (saliva, urine, blood or hair). But it is not always obvious what the result actually means. This guide explains.
What do drug tests look for?
Standard panels cover the most common drug groups:
- 5-panel: amphetamine/methamphetamine, cocaine, opiates (morphine, codeine, the heroin metabolite 6-MAM), benzodiazepines, cannabis (THC)
- 10-panel: the above + buprenorphine, methadone, MDMA, oxycodone, tramadol
- Extended panel: the above + new psychoactive substances (NPS), synthetic cannabinoids, designer benzodiazepines
What does it not show?
Drug tests show presence, not the degree of intoxication or the exact time of intake. For work environment assessments, presence is usually enough — but for medical reviews or legal proceedings, concentration measurements (quantification) may be required. Blood samples provide the most precise quantification.
Screening vs confirmation
Drug testing takes place in two steps:
- Screening: a rapid test or initial lab analysis based on antibody binding. Quick and cheap, but can give false positives due to cross-reactions with medicines.
- Confirmation: lab analysis with GC-MS or LC-MS-MS that identifies specific substances. Immune to cross-reactions and quantitative.
A "positive" result is not final until it has been confirmed. Provsvaret never reports positive results without confirmation.
How far back in time does the test show?
The detection window depends on the sample type and substance. For a complete table, see our guide on detection times. In summary:
- Saliva sample: 1–48 hours (recent use)
- Urine sample: 2–4 days for occasional use, up to 30 days for regular cannabis use
- Blood sample: 1–48 hours for most substances
- Hair test: up to 90 days for a standard 3 cm segment
What does a positive result mean?
That the substance is present in the sample at a concentration equal to or above the cut-off level. It says nothing about when the person took the substance or whether they were impaired at the time of the test. Cannabis can register several weeks after intake; alcohol is measured differently because it is eliminated quickly.
What does a negative result mean?
The substance is not present in a measurable concentration. This does NOT guarantee that the person has never used the substance — only that no residues remain in the bodily fluid at the time of the test, or that the concentration is below the cut-off.
Cut-off levels
Each substance has a cut-off level above which the test is reported as positive. Lower cut-off = more sensitive test, longer detection window. Higher cut-off = more specific, shorter window. Provsvaret uses the lab's standardised cut-off levels — see cut-off levels.
MRO review in the event of a positive
In the event of a confirmed positive result, an MRO physician reviews whether there is a legitimate medical explanation (prescription). Confirmed medical explanations reclassify the result as "negative — medical explanation".
Read on
For the legal side of testing: Can employers drug test? For how a result is handled in a workplace incident: action plan for a positive drug test.
Want to know more?
Contact us for personalized advice on drug testing and how we can help your organization.
