Quick answer
Respond to the immediate task risk, record factual observations and use a private, appropriate management and support process. Do not diagnose alcohol or drug use from behaviour alone. A policy should explain responsibilities, safe response and professional help without assuming a test or disciplinary outcome.
Why the safety concern and its cause are separate questions
A change in behaviour or performance can have several causes. HSE’s misuse guidance explicitly notes that possible signs can also relate to stress or illness.
Focus first on whether the person can safely perform the current task. Do not turn an observation into a diagnosis, an accusation or an instruction to change prescribed medicine.
Define an immediate response and private follow-up
| Stage | Appropriate management question |
|---|---|
| Immediate safety | What task or exposure must be paused or otherwise controlled? |
| Suitable assistance | Is urgent help or another appropriate support route needed? |
| Factual account | What was observed, when and during which task? |
| Private discussion | What relevant information can be discussed through the policy and appropriate process? |
| Advice and action | What professional input, workplace adjustment or management decision is needed? |
| Review | How will safe task allocation and agreed support be checked? |
Assess safety-sensitive work and consult on the policy
HSE’s safety-critical work guidance helps identify activities where impairment could have serious consequences. Consider actual machinery, vehicles, sharp tools or other relevant hazards.
Use HSE’s policy guidance to define responsibilities, reporting, immediate safeguards, confidential handling and support. Make the process understandable to supervisors and workers before an incident.
Use professional support and appropriate safeguards
HSE’s support guidance identifies suitable help for workers. Appropriate clinical or occupational-health advice can address relevant health and medication questions; managers should not prescribe treatment or medication changes.
Acas’s OH guidance explains ordinary assessment/report-sharing processes and confidentiality in the GB context. Keep information restricted to people who need it.
If screening or testing is proposed, use the official HSE guidance and competent employment/privacy advice. Do not assume every test is justified, that consent alone resolves all data duties or that a result determines a dismissal. NI employers need the NI framework and suitable NI employment advice.
Example: address the unsafe task without diagnosing the worker
A supervisor observes that someone appears unable to operate equipment safely. They follow the site arrangement to pause the task safely and obtain suitable help, then record the observations and arrange a private follow-up.
The account describes the task and behaviour, not an unsupported conclusion about substances. Further action follows the appropriate policy, evidence and advice.
Common mistakes
- Publicly accusing a worker based on appearance.
- Leaving a hazardous task running while debating the cause.
- Asking for unnecessary medical details.
- Promising an automatic testing or disciplinary result.
Next steps
Review safety-sensitive tasks and the supervisor response with appropriate competent help. Consult workers on a clear policy, support route and privacy arrangements, and train managers to use factual observations.
Use HSE’s drug and alcohol risk guidance — The official guidance supports risk management and support; individual health, testing and employment questions require appropriate professional advice.