Metals, toxins and medication
Benzodiazepinen
A urine test for benzodiazepines shows whether sleeping pills or tranquilizers have been used in the past days to weeks.
Everything about this testWhat it measures
Benzodiazepines are medicines for anxiety, restlessness and sleep problems, such as oxazepam, diazepam, temazepam and lorazepam. They are often prescribed, but are also used without a prescription. This screening test is an immunoassay that reacts to the group of benzodiazepines and their breakdown products, with a cut-off of 200 µg/l. Not every benzodiazepine is detected equally well, and the test does not say which medicine was used.
- Use of benzodiazepines in the past days to weeks, with or without a prescription
- Use of benzodiazepines that are not available as a medicine (designer benzos), such as bromazolam
Positive
A positive result means there is a benzodiazepine or one of its breakdown products in the urine above the laboratory's cut-off. According to the Trimbos Institute, a short-acting medicine is detectable in urine for up to about 3 days and a long-acting medicine for up to 30 days, even longer with long-term and regular use. Anyone taking a prescribed benzodiazepine correctly tests positive. A positive result shows that a substance is in the body; it is not a diagnosis and says nothing about dependence, the amount or the time of use.
Negative
A negative result means no benzodiazepine was found above the cut-off. This does not rule out use: some benzodiazepines are taken in a low dose and are detected less well by the test, for example lorazepam and clonazepam. Sleeping pills such as zolpidem and zopiclone are not benzodiazepines and are not detected. Diluted urine from drinking a lot can bring the value below the cut-off.
If your result is abnormal
With a positive result that may have consequences, the laboratory has the result confirmed with a second method of analysis that shows which medicine was used. The GP then goes over the medicines of the past weeks and, if needed, discusses how use can be tapered off.
Reliability
The test says something about use in the past days to weeks, not about health or the extent of use. Because many people take benzodiazepines on prescription, a result can only be interpreted if it is known which medicines someone takes. The Dutch Society for Clinical Chemistry (NVKC) states that a positive result of a screening test must be confirmed with a second, different method of analysis; a confirmation test is not included in this test.
Limitations
- Not every benzodiazepine is detected equally well; with some medicines the result can be negative, even when taken in a normal dose.
- Zolpidem and zopiclone are not detected. According to the Trimbos Institute, sertraline can actually give a positive result on a urine rapid test; confirmation with a different method is needed before a result can carry weight.
- How long a medicine is detectable differs greatly per medicine and per person; in older people and with liver problems it is longer.
- Fluid intake determines how concentrated the urine is; diluted urine can give a negative result.
How common is this
In 2024, almost 1 in 10 adults in the Netherlands (9.6 percent) had used sleeping pills or tranquilizers in the past year; most of these are benzodiazepines. 3.4 percent used them (also) without a prescription.
Who is this useful for
Useful for a medical question, for example in addiction care, when tapering off sleeping pills or tranquilizers, or with unexplained drowsiness or falls in which a benzodiazepine may play a role. In people who take a prescribed benzodiazepine, a positive result adds little.
Downsides and risks
- A negative result can give false reassurance, because not every benzodiazepine is detected equally well.
- A result without a confirmation test can wrongly be used as evidence.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results