Medicinal cannabis use is on the rise in Australia. Since its legalisation for therapeutic purposes in 2016, more employees are being prescribed cannabis products to manage conditions such as chronic pain, anxiety, or insomnia. For employers, this creates a complex challenge: how to balance respect for lawful prescriptions with the obligation to provide a safe workplace.
While medicinal cannabis is legal, it can still impair performance. This creates particular risks in safety-sensitive industries like transport, logistics, construction, and mining, where a lapse in attention or reaction time can have catastrophic consequences. Recent guidance, including a January 2025 WorkSafe WA information sheet, makes it clear that employers need to revisit their drug and alcohol (D&A) policies to address this evolving issue.
The Legal Context: What the Law Says
Medicinal cannabis is legal in Australia under prescription, but that does not remove workplace risks. Key points include:
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THC remains prohibited for drivers: Unlike alcohol, where a low concentration may be permissible, most heavy vehicle drivers and safety-critical workers are subject to a 0.00% blood alcohol concentration equivalent when it comes to THC. Even a lawful prescription does not permit driving or machinery operation if impairment is possible.
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Drug testing is not exemption-based: Workers may test positive for THC on a drug test regardless of whether their use is prescribed. This creates a dilemma for both employees and employers, particularly in transport and logistics where mandatory testing is common.
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Employer obligations remain: Under workplace health and safety (WHS) legislation, employers have a duty of care to manage risks. Allowing a worker impaired by cannabis to operate heavy machinery could expose an employer to liability if an incident occurs.
The WorkSafe WA Jan 2025 info sheet reinforces that safety obligations take precedence. Employers must recognise both the rights of employees and their duty to ensure a safe environment for all.
The Impact of Medicinal Cannabis on Work
Medicinal cannabis can affect workers differently depending on the dosage, type of product (oil, capsule, flower for vaporisation), and individual tolerance. Unlike many prescribed medications, cannabis often contains tetrahydrocannabinol (THC), the psychoactive component responsible for impairment. Even at low doses, THC can influence a person’s ability to perform tasks safely.
Common Effects on Performance
Research and workplace safety authorities highlight several potential impacts relevant to employment:
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Slowed reaction times – Workers may take longer to respond to hazards, machinery malfunctions, or sudden changes in traffic conditions.
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Reduced concentration and alertness – Sustained focus may be compromised, making routine but safety-critical tasks riskier.
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Impaired memory and decision-making – Short-term memory lapses and poorer judgement can affect the ability to follow procedures or respond in emergencies.
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Altered motor coordination – Fine motor skills may be affected, increasing the likelihood of handling errors, drops, or accidents with equipment.
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Mood and perception changes – Depending on the strain and dosage, some individuals may experience drowsiness, anxiety, or altered sensory perception.
Duration of Impairment
Unlike alcohol, which has a more predictable clearance time from the body, cannabis impairment can last longer and vary widely:
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Acute impairment may persist for several hours after use.
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Residual effects (e.g. slowed cognition, fatigue) can linger into the next day, especially with high-THC or sedating products taken at night.
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Regular use may contribute to a baseline reduction in alertness, particularly concerning for roles requiring constant vigilance.
Industry-Specific Concerns
The risks are not uniform across all workplaces and they become more acute in safety-critical roles:
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Transport & logistics: Drivers of heavy vehicles, forklifts, or machinery cannot safely operate under any impairment. Even minor delays in reaction time can lead to collisions.
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Construction & mining: Workers on high-risk sites need full coordination and alertness. Cannabis impairment can increase the risk of falls, misjudged machinery use, or breaches of safety procedures.
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Healthcare & emergency services: Reduced concentration or memory can compromise patient safety and decision-making under pressure.
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Manufacturing & warehousing: Fast-moving production lines and heavy equipment require sharp reflexes to avoid accidents.
Implications Beyond Safety
The effects of medicinal cannabis also extend to workplace culture and productivity:
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Team safety – One impaired worker can put others at risk.
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Insurance and liability – Incidents linked to impairment may affect workers’ compensation claims or expose employers to liability.
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Stigma and disclosure challenges – Employees may fear discrimination, making them reluctant to disclose prescriptions unless policies clearly protect them.
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Operational disruptions – Reassigning safety-sensitive duties from affected workers can create rostering challenges if not planned for.
The Employer’s Dilemma
Employers face a difficult balance:
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Zero tolerance vs lawful prescriptions – A blanket zero-tolerance policy may be seen as discriminatory against employees with legitimate medical conditions.
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Safety vs fairness – Employers must respect employee rights while ensuring no one’s safety is compromised.
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Testing vs impairment – A positive THC test does not necessarily indicate current impairment, but ignoring it could pose safety risks.
This is where policy clarity and medical input become essential.
Updating Drug & Alcohol Policies
To manage this emerging challenge, organisations should review and update their workplace D&A policies. Key recommendations include:
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Address prescribed medications
Policies should clearly outline expectations around prescription drug disclosure, including medicinal cannabis. Employers should encourage disclosure in a safe, non-punitive way.
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Clarify zero-tolerance limits
For safety-sensitive roles, employers may still require a zero-tolerance approach, especially where legislation mandates it (e.g. road transport).
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Focus on impairment, not just test results
A drug test alone cannot always confirm impairment. Policies should reference impairment assessments and supervisory observations as part of decision-making.
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Consult occupational physicians
Where an employee is prescribed medicinal cannabis, obtain advice from a qualified occupational physician to assess whether the worker can safely perform their role.
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Protect employee privacy
Ensure processes for disclosure and assessment respect medical confidentiality and anti-discrimination obligations.
Practical Steps for Employers
Beyond updating policies, employers can take proactive measures to manage medicinal cannabis at work:
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Training supervisors: Equip frontline managers with the skills to recognise signs of impairment and respond appropriately.
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Awareness programs: Run toolbox talks or workshops to educate staff about the risks of impairment, regardless of the substance.
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Testing solutions: Use workplace drug testing tools to maintain compliance and safety standards. Andatech offers drug testing kits and workplace breathalysers that help employers detect impairment risks on site. For high-risk roles, consider alcohol interlocks or random testing regimes.
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Case-by-case assessments: Handle medicinal cannabis disclosures individually, balancing fairness with safety.
Looking Ahead
As medicinal cannabis prescriptions continue to rise, employers cannot afford to wait for incidents to prompt action. By proactively updating policies, training staff, and using reliable workplace testing solutions, organisations can strike the right balance between compassion and compliance.
Medicinal cannabis may be legal, but workplace safety is non-negotiable. Employers must ensure that the wellbeing of all staff and the public comes first.
Conclusion
Medicinal cannabis in the workplace is not a black-and-white issue. Employers need to acknowledge its legitimacy as a treatment while upholding strict safety obligations. The key is clear policy, consistent testing, and expert guidance.
Andatech works with Australian businesses to provide drug and alcohol testing solutions, helping employers create safer, fairer workplaces. With the right approach, businesses can manage this emerging challenge responsibly and effectively.
