Drink driving and drug driving - the facts

Lesson Type
Last updated: 12 Nov 2019

Drinking and driving is against the law, and you must never drive under the influence of drugs. You should even avoid driving after taking some types of medication, because certain medicines can alter your mental state or make you drowsy.

What is the legal limit for drinking and driving?

You can legally drink a very small amount and still be able to drive:

  • 35 microgrammes of alcohol (22 in Scotland) per 100 millilitres of breath

  • 80 milligrammes of alcohol (50 in Scotland) in 100 millilitres of blood

  • 107 milligrammes of alcohol (67 in Scotland) per 100 millilitres of urine

How many drinks is that?

Officially, it’s impossible to say how many microgrammes of alcohol are contained in a single drink. Amounts of alcohol are usually talked about in units. To give you a rough idea, one unit of alcohol is 10ml of pure alcohol. Sometimes bottles of alcohol have guidelines printed on them, indicating how many units each glass of alcohol should contain. Always check the label. The golden rule is not to drive at all after you have had a drink, especially if you are unsure.

I was drunk last night, can I drive the next day?

Often when people have been drinking the previous night, they don’t think that they are drink driving the next day. But each unit of alcohol takes 1 hour to be broken down, so it’s difficult to judge when the alcohol has left your system after you have been drinking. To get an idea, see this example from drinkaware.

“Imagine you’re drinking until three or four in the morning and you wake up at 8 am,” says Dr Wallace. “If you’ve had six or seven units, you could still have several units of alcohol in your body when you start your day. This is because your body can only process around one unit an hour. With several units of alcohol still in your body you would still be over the drink drive limit”

Driving should be avoided the next morning, even if you think you have sobered up - that goes for driving lessons too! Black coffee, toast and cold showers might make you feel fresher, but they don’t affect how fast the alcohol leaves your body.

Is drug driving illegal?

It’s illegal to drive under the influence of drugs.

What happens if I get caught drug driving?

If you are caught driving with illegal substances in your body you will be banned from driving for 12 months, get a criminal record and be fined up to £5000. As well as all this:

  • A specific record will remain on your driving licence for 11 years
  • If you’re convicted of dangerous driving, you will get up to 14 years in jail
  • If you were driving for work, your employer will find out when you produce your licence
  • The price of your car insurance will increase
  • Your conviction may stop you entering other countries such as the USA

Is it also classed as drug driving if I took legal medication?

Sections 4(1) and (2) of the Road Traffic Act 1988 state: a person who, when driving or attempting to drive – or in charge of – a mechanically propelled vehicle on a road or other public place, is unfit to drive through drink or drugs is guilty of an offence.

Whether the drugs you have taken are legal or illegal, if they affect your ability to drive you could get into serious trouble. Always read the leaflet that comes with your medicine very carefully.

The law also says that anyone who develops a health condition should tell the Driver and Vehicle Standards Agency (DVSA) at once. This is because if you do have an accident and your health was a contributing factor you can be prosecuted. Your insurance might also become invalid.

Image via West Midlands Police.