Drug Driving

Driving after using drugs can be dangerous, even if you feel fine. Drugs can affect your reaction time, judgement, coordination, vision, and concentration, all of which are essential for safe driving.

In England, Scotland and Wales it is illegal to drive if:

  • you are unfit to drive because of drugs, whether they are legal or illegal, or

  • you have over specified limits of certain drugs in your blood, even if you do not feel impaired.

This applies to illegal drugs, prescribed medication, and some over-the-counter medicines.

How drug driving is enforced

Police can stop you if they suspect drug use and:

  • carry out a field impairment assessment, such as asking you to walk in a straight line

  • use a roadside drug test, currently screening for cannabis and cocaine

If officers believe you are unfit to drive, you can be arrested and required to give a blood or urine sample at a police station. Blood testing is used to confirm drug levels.

You can be charged even if you believe your driving was not affected.

Drug limits and impairment

The law uses two separate tests:

  1. Specified drug limits in the blood

  2. Fitness to drive, assessed by police at the roadside

These work together. Being below a set limit does not automatically mean it is legal to drive. If your driving is affected, it is still an offence.

Equally, being over a limit can be an offence even if you feel fine.

Detection times and drug levels

Drug detection times vary widely and depend on many factors, including:

  • age

  • sex

  • body composition

  • dose taken

  • frequency of use

  • how the drug was taken

Detection times are approximate only and should never be used to judge when it is “safe” to drive.

Some examples:

  • Cocaine may be detectable for hours to days, especially with repeated use

  • Cannabis (THC) can remain detectable for days in regular users due to storage in body fat

  • Ketamine may clear relatively quickly at higher levels, but lower legal limits mean detection can last much longer

  • Benzodiazepines (such as diazepam, lorazepam or clonazepam) are often present continuously in people prescribed them daily

The safest option is always not to drive after using drugs.

Elimination/Detection Times
Controlled drug Limit (mcg/L blood) Comments Elimination / detection times (other factors apply)
Benzoylecgonine (BZE) 50 Main metabolite of cocaine and what is tested for After ~100 mg cocaine (snorted), detectable up to ~30 hours. Chronic use at least 5 days. Single dose likely 3–12 hours, but unlikely to be fully clear after 3 hours and impairment may still be present
Clonazepam 50 Benzodiazepine; linked to increased traffic accidents with multiple prescriptions Likely below detection after ~2 days following a single dose. Daily prescribed use may result in continuous presence
Cocaine 10 Presence usually indicates recent use After a single average dose, usually not detectable after ~12 hours. Heavy or repeated use may be 24–48 hours
Delta-9-Tetrahydrocannabinol (THC) 2 Main psychoactive compound in cannabis Single use usually 9–12 hours. Frequent or heavy users may test positive for many days due to stored THC being re-released
Diazepam 550 Benzodiazepine; sedative effects increase accident risk At 5–15 mg, peak effects 15–90 minutes. Eliminated after ~30 hours. Daily prescribed use may lead to constant presence
Flunitrazepam 300 Benzodiazepine associated with increased accident risk Peak levels ~1 hour after single dose, or ~3 hours after daily dosing for a month. Ongoing prescribed use likely results in continued detection
Ketamine 20 Effects depend on route of use At ~200 mcg/L, elimination within ~6 hours. At the much lower legal limit, detection can last significantly longer
Lorazepam 100 Benzodiazepine associated with increased accident risk At ~4 mg, likely eliminated after ~24 hours. Daily prescribed use may result in ongoing detection
Lysergic Acid Diethylamide (LSD) 1 Effectively zero-tolerance limit Detection time largely irrelevant due to extremely low threshold
Methadone 500 Maintenance medication; dose-dependent Levels peak ~4 hours after a 100–120 mg dose and usually fall below limit after ~24 hours. Ongoing prescribing often means continued detection
Methamphetamine 10 Very low detection threshold Likely eliminated after ~24 hours, but low limit allows detection long after effects have worn off
MDMA (Ecstasy) 10 Includes methylenedioxymethamphetamine Moderate single dose (<100 mg) ~24 hours. High or repeated dosing up to ~38 hours or longer
6-Monoacetylmorphine (6-MAM) 5 Active metabolite of heroin Detectable between ~30 minutes and 2 hours after a single dose
Morphine 80 Breakdown product of heroin and other opioids Dose-dependent. Single average dose detectable up to ~10–15 hours
Oxazepam 300 Metabolite of several benzodiazepines Likely eliminated after ~18 hours. Daily prescribed use may result in continuous presence
Temazepam 1000 Benzodiazepine; metabolised to oxazepam Likely eliminated after ~12 hours. Daily prescribed use may result in continuous presence

This information is taken from Release. If you have a specific question please contact theirexpert drugs and legal advisers on 0207 324 2989 or ask@release.org.uk

Prescription medicines and driving

Legal drugs include prescription and over-the-counter medicines.

It is illegal to drive if a prescribed or legal drug impairs your driving, even if you are taking it correctly.

Some medicines commonly linked to drug driving offences include:

  • amphetamines (for example dexamphetamine)

  • clonazepam

  • diazepam

  • flunitrazepam

  • lorazepam

  • methadone

  • morphine and other opioid medicines (including codeine, tramadol and fentanyl)

  • oxazepam

  • temazepam

You may be allowed to drive if:

  • the drug has been prescribed to you

  • you have followed medical advice on how to take it

  • it is not affecting your ability to drive, even if blood levels are above the legal limit

If you are unsure, speak to your doctor, pharmacist or healthcare professional before driving.

Penalties for drug driving

If you are convicted of drug driving, you may face:

  • a minimum 1-year driving ban

  • an unlimited fine

  • up to 6 months in prison

  • a criminal record

Your driving licence will show the conviction for 11 years.

If someone dies as a result of drug-driving, the maximum penalty is life imprisonment.

Wider impacts of a conviction

A drug-driving conviction can also:

  • significantly increase car insurance costs

  • affect employment, especially if you drive for work

  • cause problems travelling to countries such as the USA

Staying safe

There is no reliable way to know when drugs have fully left your system. Feeling “okay” does not mean you are safe or legal to drive.

The safest choice is simple: if you have taken drugs, do not drive.

Plan ahead where possible, use public transport, taxis, or arrange a lift with someone who has not used drugs.

Support from Wirral Ways

If drug use is affecting your life, driving, or safety, support is available.

We offer confidential, non-judgemental support including:

  • advice around drug use and risks

  • harm reduction support

  • treatment options if you want to reduce or stop using drugs

  • support for prescribed medication and substance use together

If you are worried about drug driving or want advice, you can speak to us directly or get in touch with specialist drug and legal advisers such as Release.

Last Updated on 9 February 2026