Help! My employee tested non-negative to a drug test at work
When a drug test at work returns a non-negative result, it can create uncertainty for managers, team leaders and, of course, employees. There are some questions around this process too, such as what does non-negative actually mean, what happens next and how should workplaces respond in a way that is lawful, fair and supportive?
Understanding the process helps remove fear, protect your business and ensure safety remains the priority. So we’ve taken the liberty to answer these questions in case you ever find yourself in this unfortunate position.
What does a non-negative result mean?
A non-negative result does not mean someone has failed a drug test. It means the initial onsite screening has detected a substance at or above the screening threshold and requires further investigation. Each substance and method of testing has a screening threshold that is set in accordance with the Australian standards.
Onsite screening devices are designed to be sensitive. Their role is to identify specimens that need laboratory confirmation, not to deliver a final diagnosis.
That’s why, at this stage we strongly recommend that:
- no conclusions should be drawn
- no disciplinary action should occur
- the result is considered preliminary.
In workplace drug and alcohol testing, non-negative and positive mean different things.
A non-negative result is a preliminary on-site screening outcome. It means the screening device has detected something at or above its cut-off level, so the result cannot be reported as negative and must be sent to a laboratory for confirmation. At this stage, it is not a failed test, and no conclusions should be drawn. Medications, metabolites or cross-reacting substances can all trigger a non-negative screen.
A positive result is a confirmed laboratory outcome. It is only reported after a NATA-accredited laboratory (like us) has identified a specific drug or alcohol at or above the confirmation cut-off concentration, using highly specific analytical methods.
In short:
- non-negative = screening flag, investigation required
- positive = confirmed result, policy applies.
This distinction protects both employees and employers by ensuring fairness, accuracy and legal defensibility in workplace testing.
Why laboratory confirmation is required
Any non-negative drug test at work must be confirmed by a NATA-accredited laboratory. Laboratory testing uses highly specific analytical methods to identify the exact substance and concentration present.
This step is essential because:
- some medications can trigger a screening result
- laboratory testing distinguishes prescribed, over-the-counter and illicit substances
- confirmation ensures results are legally defensible (in accordance with your workplace policy).
In most cases, confirmation results are available within a short timeframe.
What are your legal obligations as an employer?
Under Australian workplace health and safety laws, employers must ensure workers are not exposed to risks to health and safety so far as is reasonably practicable. This includes managing potential impairment.
When a non-negative result occurs, employers are generally required to:
- follow their documented drug and alcohol policy
- manage risk while results are pending
- apply procedures consistently and without bias
- maintain confidentiality and privacy.
Ignoring or mishandling a non-negative result can increase liability if an incident occurs.
Should the worker be stood down?
This depends on your workplace policy, the role involved and the substance detected. Check out this expensive mistake when one workplace did not have a solid policy in place.
In safety-sensitive roles, it is common practice to stand a worker down from duties while confirmation is pending. This is not a punishment. It is a temporary risk-control measure to protect the individual, their colleagues and the public.
Clear policies help ensure these decisions are applied fairly and consistently. We recommend not waiting until it’s too late to have an up-to-date and explicit policy.
How team leaders can respond appropriately
How managers handle a non-negative drug test at work can shape trust and culture. As we’ve looked at, testing can be a way of supporting staff and not as a punishment.
Best practice includes:
- remaining calm and factual
- avoiding assumptions or accusations
- explaining the confirmation process clearly
- reinforcing confidentiality
- focusing on safety, not blame.
Managers should never attempt to interpret results themselves. Expert toxicology support is critical.
Supporting wellbeing, not just compliance
A non-negative result can also signal that someone may need support. It’s fair to say that it could also be an indicator that the broader team could highly benefit from a workplace wellbeing program.
Many workplaces now take a wellbeing-led approach, which may include:
- employee assistance programs
- clear pathways for wellness or even rehabilitation where appropriate
- education around medications, fatigue and impairment
- early intervention rather than escalation.
When handled well, an alcohol and drug test at work can become a point of support rather than conflict.
The most effective way to manage non-negative results is to prevent confusion before they occur by having clear, up-to-date drug and alcohol policies, documented procedures, trained managers, and access to professional testing and toxicology advice, turning reactive incidents into part of a broader safety and wellbeing framework.
AusHealth supports workplaces across Australia with compliant drug and alcohol testing, expert toxicology interpretation, and policy creation or review.
We help organisations:
- understand and manage non-negative results
- develop clear, legally robust policies
- train leaders to respond appropriately
- embed testing into a broader culture of care.
If your workplace conducts drug testing, having the right systems in place before an issue arises makes all the difference.
Talk to AusHealth about strengthening your approach to drug testing at work.
FAQ
“How likely are false negatives or false positives?”
False negatives are rare but can happen, often due to tampering. Non-negative onsite results sometimes confirm as negative, especially when medications are involved. Confirmation testing in the lab is precise and eliminates false positives.
About false negatives: sometimes a test can be negative in the onsite screening because the cut-off is higher than the laboratory cut-off. For example, if a donor had 8 µg/L of THC in oral fluid, it will be negative in the onsite test (cut-off 15 µg/L) but confirmed positive in the lab (cut-off 5 µg/L). Tampering is also a possible cause of false negatives.
About false positives: technically, there are no false positives. Screening devices use antibodies that identify chemical structures. These antibodies detect a class of drugs or chemicals that resemble one another. For example, cannabinoid antibodies will identify over 60 chemicals that resemble THC in cannabis smoke and report non-negative at levels above 15 µg/L. Amphetamine antibodies will detect amphetamine, ecstasy, amphetamine metabolites, pseudoephedrine and phentermine — all of which are amphetamine-type stimulants — and report non-negative at 50 µg/L.