Workplace Drug Testing in the UK: The Most Common Substances Found and Why They Matter

A smarter way to test — keeping your business safe, supportive, and productive.

Running a business isn’t just about profit — it’s about people. When employees are well, focused, and safe, the entire workplace thrives.

That’s why more UK companies are turning to workplace drug testing — not as a punishment tool, but as a smarter way to protect staff, meet legal responsibilities, and prevent accidents before they happen.

Whether you’re searching for drug testing near me or exploring how to build a healthier team, this guide explains the most common substances found in UK workplace drug tests — and why understanding them matters.

1. Cannabis (THC)

What it is:Cannabis is one of the most frequently used drugs in the UK. While it can be prescribed for certain medical conditions, recreational use is still illegal.

Why businesses test for it:

• THC (the active part of cannabis) can slow reaction time, reduce coordination, and affect decision-making.

• These effects make it unsafe for employees in roles involving machinery, driving, decision making, or high-risk environments.

• Cannabis can stay in the body for several days, especially in urine tests, which is why it’s a key part of most substance misuse testing programmes.

2. Cocaine

What it is:Cocaine is a powerful illegal stimulant. It creates a quick burst of energy and confidence but wears off fast — often leaving users more irritable or impulsive.

Why it’s tested in the workplace:

• Cocaine affects judgment and increases risk-taking behaviour.

• This can put both the user and their colleagues at serious risk.

• It’s only detectable for a short time, so regular workplace drug testing helps catch use early.

3. Opiates (e.g. heroin, codeine, morphine)

What they are:Opiates include both illegal drugs (like heroin) and prescribed painkillers (such as codeine). While some are legal with a prescription, they can still affect workplace safety.

Why employers test for them:

• Opiates can cause drowsiness and reduce concentration.

• Even if prescribed, they can still impair safe performance in many roles.

• These substances stay in the body for several days.

Misuse of prescribed painkillers is common. Many workers don’t realise that legally prescribed medication can still lead to a failed drug test if misused.

4. Amphetamines (e.g. ecstasy, methamphetamine)

What they are:Amphetamines are stimulants sometimes prescribed for conditions like ADHD. Illicit versions, like ecstasy, are often used recreationally.

Why they’re part of workplace drug testing:

• These substances can lead to overconfidence, poor decision-making, and unsafe actions.

• They’re often used on weekends and can be detected for up to many days afterwards.

5. Benzodiazepines

What they are:Commonly prescribed for anxiety and sleep disorders, benzodiazepines can be helpful — but they’re also frequently misused.

Why employers include them in substance misuse testing:

• They can cause sleepiness, slow reaction times, and reduce focus.

• This makes them risky in safety-critical roles.

• Some can remain in the body for weeks, depending on use.

6. Alcohol

What it is:Alcohol is legal, but it's one of the most common substances involved in workplace accidents.

Why it’s part of workplace drug testing:

• Alcohol reduces coordination and slows reactions.

• Even small amounts can increase the risk of mistakes — especially in roles involving driving, tools, or physical work.

• Many incidents happen not during drinking, but “the morning after,” when the body hasn’t fully cleared the alcohol.

Why This Matters for Your Business

Every business wants to grow, but growth starts with safety. By knowing which substances are commonly misused, you can put the right substance misuse testing procedures in place — not to punish staff, but to protect them.

At First Cohort, we believe in a smarter way to test. That means giving you tools that support your business instead of holding it back. Our approach to workplace drug testing is built on fairness, accuracy, and a genuine interest in helping employees succeed — not fail.

Looking for Drug Testing That Works for Your Business?

If you’re responsible for health and safety, HR, or management, and you're searching for drug testing near me, we’re here to help.

We offer straightforward advice, professional testing services, and ongoing support — all tailored to your industry. Whether it’s regular testing, post-incident checks, or setting up a brand-new policy, we’ll help you do it right.

Dave