Medications & Workplace Safety – Navigating Risk, Rights & Responsibility

Can a Prescription Put Your Job at Risk?

Medicinal Cannabis prescriptions in Australia have surged from 17,000 in 2020 to over 700,000 in 2023, reflecting a significant shift in how workplaces must manage safety, compliance, productive and employee wellbeing. ¹

What happens when a legally prescribed &/or over-the-counter (OTC) medication affects an individual’s ability to drive, operate machinery, or perform their duties safely and in a productive manner at work?

Workplaces and patients are navigating a complex intersection of health, safety, and legal compliance that raise important questions around driving, operating machinery, workplace safety, productive, responsibilities, duty of care and risk management.

Medicinal Cannabis has been legal in Australia since 2016, available only via prescription under the Therapeutic Goods Administration’s (TGA) Special Access Scheme or Authorised Prescriber Scheme and products typically contain²

CBD (Cannabidiol)
Non-psychoactive, less likely to affect performance but may cross-react in drug testing.
THC (Tetrahydrocannabinol)
Psychoactive, with potential to affect cognitive and motor functions, with the potential to pose risks in safety-sensitive roles and driving.

TGA insights on Cannabis Forms and Safety

Inhaled (Flower/Buds)
Rapid onset, shorter duration. THC peaks quickly and is detectable in oral fluid within 4–6 hours.
Ingested (Oil)
Slower onset, longer-lasting effects, remains in the bloodstream longer and may cause subtle, prolonged effects. ²
Does the Form (ie Flower/Buds vs Oil) change the effect?
Yes, the form of Medicinal Cannabis can alter the effects on patients; particularly in terms of onset and duration.

THC Detection Window in Oral Fluid

THC can be detected in oral fluid from as early as 15 minutes up to 24 hours in occasional users, and up to 7–8 days in chronic users, due to residual deposition in the oral cavity and slower clearance rates.³
Oral fluid tests detect the parent THC compound, not just metabolites, making them highly effective for identifying recent cannabis use, especially in safety-sensitive environments.
Any not-negative, unconfirmed result must undergo confirmation testing through a National Association of Testing Authorities (NATA) accredited laboratory, which can verify consistency with declared prescriptions, medications and rule out cross-reactivity.

Driving and THC

Driving with any detectable THC is illegal in all Australian states, even with a prescription. This zero-tolerance policy complicates employment in transport, logistics, and other driving-intensive roles.

AS/NZS 4760:2019 Procedure for specimen collection and the detection and quantification of drugs in oral fluid.
THC Screening Cut-off 15 ng/mL
THC Confirmation Cut-off 5 ng/mL

Drug Classifications and Potential Impact to the Workplace

Depressants (e.g., alcohol, benzodiazepines) can reduce alertness and coordination.
Stimulants (e.g., amphetamines, cocaine) may cause overexertion, impulsivity, or aggression.
Hallucinogens (e.g., LSD, mushrooms) can distort perception and effect decision-making.
Cross-Reactivity prescription stimulants like Dexamphetamine and Vyvanse may cross-react and produce not-negative, unconfirmed results. Disclosure is essential.

Testing and Confirmation – Legal Requirements

Workplace drug and alcohol testing must align with your organisation’s drug and alcohol policy and procedure, industry-specific legislation and WHS obligations.

Under Work Health & Safety Laws

Industry Expertise & Support Available

With over 35 years of industry experience, our team brings unmatched expertise in workplace safety, compliance, and training. We combine deep technical knowledge with real-world insights to help organisations navigate complex challenges around prescribed and over-the-counter medications; knowledge that is reflected in our revised training materials and support services.

We don’t just supply testing solutions – we empower workplaces with the education, tools, and guidance needed to make informed, fair, and safety-focused decision.

A Balanced Approach

Prescription and over the counter medications are here to stay, and its presence in the workplace demands awareness, training and up to date accurate policies and procedures. By combining fair testing practices, clear communication, and a commitment to safety, employers can support both employee health and operational integrity.

CLICK HERE to download a free copy of our Supervisor’s Quick Guide to Managing Medication-Related Disclosures.

Sources

Australian Institute of Health and Welfare. Medical Marijuana in the National Drug Strategy Household Survey (NDSHS).
Therapeutic Goods Administration (TGA). Medicinal Cannabis Guidance Documents.
Drummer OH. Pharmacokinetics of Illicit Drugs in Oral Fluid. Forensic Science International. 2005;150(2–3):133–142. DOI: 10.1016/j.forsciint.2005.02.065

Supervisor Training Available on Reasonable Suspicion here

Policy & Procedure Review Service here

Explore our brand new Cross-Reactivity Course here