When can you legally drug test employees in the UK?

We understand; you’re cautious. With worker and customer safety a growing concern, drug testing in the workplace is becoming more common, particularly in safety-critical industries.

Under UK law, though, employers can’t test staff arbitrarily or excessively. You must ensure that, while protesting your business, you’re also treating your employees fairly and legally.

Whether you're planning to introduce a drug and alcohol policy or already have one in place, it's important to understand when drug testing is legally permitted, and how to implement it correctly.

This guide explains the legal boundaries, employee rights, and best practices for workplace drug testing in the UK.

Why drug testing at work is on the rise

More UK businesses are adopting rapid drug tests as part of their health and safety risk management. But why has workplace drug testing become so commonplace?

The Health and Safety Executive (HSE) requires employers to ensure a safe working environment, which can include addressing impairment from drugs or alcohol. This is especially relevant in industries like transport, construction, manufacturing, and healthcare, where impairment can put lives at risk.

According to the Chartered Institute of Personnel and Development (CIPD), 39 % of employers with safety‑critical roles test for drugs/alcohol. On top of that, 24 % of employers without safety‑critical roles have a policy enabling testing when there is reasonable suspicion..

Introducing clear, lawful testing can help employers:

• Reduce accidents and liability

• Meet legal safety obligations

• Support employees with substance issues early

• Demonstrate due diligence in regulated environments

When are you allowed to drug test employees in the UK?

Here’s the important point: there’s no automatic right for employers to test employees for drugs. Your workers have clear rights when it comes to being monitored at work.

You should first ensure you have a lawful basis (which may include consent, contract, legal obligation or legitimate interests) for applying drug or alcohol testing. You must also provide clear information to employees about what testing involves and how results will be used.

To stay within the law, you must meet the following conditions:

1. You have your employees’ informed consent

You can only carry out a workplace drug test if the employee has agreed to it, usually in writing.

Consent is typically given:

• As part of a contract of employment

• Via a staff handbook or policy

• On a case-by-case basis, such as pre-employment testing

Employers cannot legally force testing without consent. You should be especially cautious about relying on consent if the worker cannot refuse the test without penalty.

2. Testing is justified and proportionate

Drug testing should only be used when it’s relevant to the job and there’s a clear risk to health, safety, or performance. This includes roles:

• Involving machinery, driving, or medical care

• With high responsibility for public safety

• In sectors with regulatory oversight (e.g. aviation, rail)

Random testing is legally permitted, but you must be able to justify:

• Why it’s necessary

• How it will be conducted fairly

• Who it applies to; everyone in that risk group, not selected individuals

3. You follow a clear, written policy

A workplace drug and alcohol policy should outline:

• Why testing may take place

• When and how it will be done

• How results are handled

• The consequences of a positive test

• Employee support options

This protects both you and your employees and reduces the risk of disputes or tribunal claims.

4. Test methods are reliable and secure

If you’re using rapid test kits in the workplace, they must meet UK quality standards. That includes:

• CE or UKCA marking

• Clear detection thresholds (cut-off levels)

• Minimal risk of contamination or error

• Easy-to-follow procedures and documentation

At Rezure, our rapid workplace drug test kits are designed specifically for on-site use. These tests offer clear results in minutes and reliable detection for up to 10 common substances.

What about pre-employment or random drug testing?

Pre-employment drug testing is legal, but only if:

• The role justifies it (e.g. safety or compliance reasons)

• Candidates are informed up front

• Testing is applied fairly and consistently

Random drug testing is also allowed under UK law. However, it must be non-discriminatory and applied in accordance with a clear policy. You cannot single out individuals unless you have specific concerns, such as visible signs of impairment or accidents under investigation.

Are there any legal risks to at-work drug testing?

Yes. Drug testing is a form of medical data collection, and mishandling it can breach the UK General Data Protection Regulation (UK GDPR).

To ensure you are testing legally and preventing any possible discrimination, you must:

• Only collect information that’s necessary and proportionate

• Keep results confidential

• Store data securely and only for as long as needed

• Let employees challenge or verify results

Failing to do so can lead to legal complaints or tribunal action. It’s also vital that any disciplinary action taken as a result of a test is fair, documented, and includes the chance to respond.

FAQs: Workplace drug testing in the UK

Can an employee refuse a drug test at work?

Yes. Unless they’ve signed a contract or policy agreeing to it, employees can refuse to be tested. Refusing without a valid reason, however, could be a disciplinary matter if testing is part of the company’s health and safety policy.

What happens if someone fails a drug test at work?

The response depends on the employer’s policy. Some companies may offer support through occupational health or referrals, while others may initiate formal disciplinary action. Consistency and clarity are key.

Are rapid drug tests accurate enough for workplace use?

Yes, when used correctly. Rezure’s CE-marked urine and saliva tests are designed for reliability, with defined cut-off levels and fast results. Any non-negative result should be followed by a confirmatory lab test.

Key takeaways

1. Drug testing in the workplace is legal, but only with informed consent and clear justification.
2. Testing should be proportionate to the role, especially in safety-sensitive sectors.
3. Employers must follow data protection rules and handle results confidentially.
4. A clear written policy is essential to protect both employer and employee rights.
5. Rapid tests like Rezure’s can provide quick, reliable results, but should be part of a wider policy.

Ready to introduce workplace drug testing?

Rezure’s rapid workplace drug test kits are trusted by UK employers for their speed, accuracy, and ease of use.

Equip your team with reliable results today: Explore our workplace kits