BZO on a drug test means benzodiazepines. On a urine test cup or a result, those three letters mark the benzodiazepine panel. Below: what that line can tell you, why a prescription or an unrelated medicine can turn it positive, and what a laboratory report lists instead.
BZO stands for benzodiazepines
Benzodiazepines are a class of prescription sedatives. They are prescribed for anxiety and for sleep, and the familiar names include Xanax, Valium, Klonopin and Ativan.
Test strips carry short codes instead of full drug names, and the code for this class is BZO. A Testr report prints it as BZO (Benzodiazepines), one of 14 drug panels. The rest are covered in every drug test abbreviation, decoded.
BZO is easy to confuse with BAR. Both are sedative panels, but BAR is the barbiturates panel: an older, separate class with its own strip and its own 300 ng/mL cutoff.
BZO works as a class screen. It responds to benzodiazepines as a group, so a positive line does not say which one was taken or how much.
What the BZO line actually reports
A certified collector reads the 14-panel rapid urine screen on site. BZO turns presumptive positive at 200 ng/mL or more and reads negative below that. No number is printed. The line only says which side of the cutoff the specimen fell on.
A negative BZO therefore means less than 200 ng/mL in that specimen at the time it was collected. It is not proof that no benzodiazepine was ever taken. The panel's published window: detectable for 1-3 days after short-acting types, up to several weeks with long-acting drugs or regular use, at a 200 ng/mL cutoff. Those ranges are typical, not fixed. The benzodiazepine page breaks down how long benzodiazepines stay in your system in more detail.
The cassette's three validity strips (pH, oxidants and creatinine) test the specimen itself and say nothing about benzodiazepines. The difference between negative, presumptive positive and laboratory-confirmed is laid out in how to read a Testr drug test result.
Will a prescribed benzodiazepine make BZO positive?
It can. The strip reacts to the whole class, and a benzodiazepine taken exactly as prescribed, whether Xanax, Valium, Klonopin, Ativan or another, is still in that class. The on-site read cannot tell a prescribed dose from any other source. It records presumptive positive or negative and nothing else.
A prescription is taken into account at the laboratory stage. Every laboratory report is reviewed by a Medical Review Officer (MRO), a physician who reviews laboratory-confirmed results and accounts for valid prescriptions before the report is released. A rapid-only visit produces no laboratory report, so the record shows the on-site read by itself.
Medicines that are not benzodiazepines
Sertraline (Zoloft) and oxaprozin (Daypro) are not benzodiazepines, yet benzodiazepine screens are documented to react to both. When one of them sets off BZO and no benzodiazepine is involved, that is a false positive in the plain sense: the strip responded, but not to its own class.
That is the limit of a class screen. It reacts to related compounds, not to one named drug. Laboratory confirmation works the other way round, looking for specific benzodiazepine compounds one at a time and reporting each with a measured level.
The other panels each have their own list, set out in what can cause a false positive, panel by panel.
What the laboratory reports for benzodiazepines
Under the Rapid Test with Laboratory Confirmation, the specimen travels sealed, with its chain of custody intact, to a CAP-accredited laboratory for LC-MS/MS testing. Instead of one line for the class, the laboratory menu lists seven benzodiazepine compounds, each with its own cutoff:
7-Aminoclonazepam, 50 ng/mL
a-Hydroxyalprazolam, 50 ng/mL
Alprazolam, 20 ng/mL
Lorazepam, 50 ng/mL
Nordiazepam, 50 ng/mL
Oxazepam, 50 ng/mL
Temazepam, 50 ng/mL
The laboratory lists chemical names, not brand names. Alprazolam, for example, is the generic name for Xanax, and lorazepam the generic name for Ativan. The laboratory gives a measured level for each compound, in about 72 hours, and the MRO review comes before the report is released.
The two sets of numbers are not comparable. The 200 ng/mL beside BZO applies to the class read as one. Each laboratory cutoff applies to a single named compound. The full laboratory menu covers 81 substances in 31 drug classes.
If the visit was booked as the At-Home Rapid Test, the app allows an upgrade to laboratory confirmation for 2 hours after collection, a limit set by specimen viability. The 2-hour upgrade window walks through that choice and its timing.
Why BZO can read differently on another test
BZO is a label, not a standard. Two kits can print the same three letters and set different cutoffs, and the cutoff decides where negative ends and presumptive positive begins.
Some tests have no BZO line at all. A 5-panel covers amphetamines, cocaine, THC, opiates and PCP only, so it says nothing about benzodiazepines. A 10-panel adds five more, and benzodiazepines are among the most common additions, but the extra five are not a fixed list: they vary with the kit and with what the employer orders. 5-panel, 10-panel and 14-panel tests compared lays out the differences.
Testr offers no smaller panel. Every visit screens all 14, each on its own line of the record, so BZO is there whether or not a policy asks for it. What a workplace policy requires is a question for employment counsel.
Getting a BZO screen in Los Angeles
To schedule, use the Testr iOS app or testrla.com/book and choose a 30-minute arrival window. Windows open between 7 AM and 7 PM on every day of the week, and the earliest can start in as little as 3 hours from when you book.
The certified collector who comes to the door is in plain clothes, arrives in an unmarked vehicle, and confirms identity using the 4-digit PIN that the booker's app displays. At collection, the specimen's temperature is taken. Next it is sealed into a tamper-evident container and photographed, and the collector and the person tested each sign for it. Each order has a chain-of-custody code of its own.
One booking covers one person. Parents, professionals such as therapists, and employers can book on someone else's behalf, and that person's consent is recorded at booking. When the person tested is a minor, a parent or legal guardian must be there from start to finish and signs the consent on the minor's behalf. See Testr for parents and Testr for professionals.
Only the account holder receives the result, in the app or as a PDF at testrla.com/account, unless they give written consent for it to go to a named third party. Testr is not a DOT collection site and tests urine only; DOT vs non-DOT drug testing explains the difference. To pick a window, book a visit.
Questions people ask
What does BZO stand for on a drug test?
Benzodiazepines, the prescription sedative class that includes Xanax, Valium, Klonopin and Ativan. A Testr report prints the panel as BZO (Benzodiazepines).
What is the cutoff for BZO?
Testr's screen sets it at 200 ng/mL. A specimen at that level or higher reads presumptive positive, and anything lower reads negative. Other kits can put a different cutoff behind the same code.
Can Zoloft cause a positive BZO?
It can. Benzodiazepine screens are documented to react to sertraline (Zoloft) and to oxaprozin (Daypro), though neither is a benzodiazepine. Laboratory confirmation looks for specific benzodiazepine compounds rather than the class.
Will Xanax show up as BZO?
It can. Alprazolam, the generic name for Xanax, is a benzodiazepine, so the BZO panel screens for it at 200 ng/mL. On the laboratory menu, alprazolam has its own 20 ng/mL cutoff.
Does a positive BZO show which benzodiazepine was taken?
No. The strip responds to the class as a whole. Only laboratory confirmation names individual compounds and gives their levels.
Is BZO on a 5-panel drug test?
No. A 5-panel is limited to amphetamines, cocaine, THC, opiates and PCP. Benzodiazepines are one of the most common 10-panel additions, but not every 10-panel kit includes them. Every Testr visit screens all 14 panels, BZO among them.