Tema 32: alcohol and drugs at the wheel in the DGT exam

Alcohol has figures (0.25 and 0.15) and test rules; drugs have a saliva rule. The rest is understanding what alcohol does to you.

Reviewed on 6 October 2026 · sources: BOE and DGT

The exam asks for the alcohol limits, the test rules and the saliva rule for drugs.

The general driver does not exceed 0.25 mg/l in breath or 0.5 g/l in blood. Limit 0.15 mg/l (0.3 g/l): novice in the first 2 years, goods over 3,500 kg, more than 9 seats, public service, school, dangerous goods and emergency.
Every driver must take the test; a preventive check is enough. If positive, it is repeated at least 10 minutes later.
The drug check uses a saliva test, not exhaled air.
The DGT manual teaches that the only safe rate is 0.0.

Watch out: a prescribed medicine can be an offence. A prescription is not a licence to drive.

In DrivingLingo: study the road signs, review fatigue and distractions and crashes and the PAS routine, then practise with the .

Source: RGC art. 20; LSV art. 14.1; RGC art. 21; RGC art. 27.1; LSV art. 14.2, 14.3 and 14.5; DGT manual (teaching, not statute)

Key rules of topic 32

The general driver does not exceed 0.25 mg/l in breath or 0.5 g/l in blood.

Limit 0.15 mg/l (0.3 g/l): novice in the first 2 years, goods over 3,500 kg, more than 9 seats, public service, school, dangerous goods and emergency.
Criminal offence: more than 0.60 mg/l in breath or 1.2 g/l in blood. Under 18: 0.0.

Every driver must take the alcohol test, and a preventive check is enough, with no accident or symptom.

It is normally done with an approved breathalyser on exhaled air.
If positive, it is repeated: the second test comes at least 10 minutes later, and you may check this.
You may contrast with a blood or urine test or similar, not only a repeat breath test.

The same amount of alcohol gives different rates depending on the person and how they drink.

Person: lower weight, being a woman, under 18 or over 65, pregnancy, stress or illness increase the effect.
Drink: gin and whisky reach the blood sooner than wine or beer; mixing them with tonic or soda speeds it further.
Drinking slowly and eating first slow absorption.

The only safe rate is 0.0: drink nothing if you are going to drive.

The peak comes 1 hour after drinking, and then the effects fall very slowly, not all at once.
Sleeping does not speed elimination: alcohol is cleared more slowly while you sleep.
On medication, do not drink: painkillers, cough suppressants, antihistamines and psychotropics already cause drowsiness and slow reflexes, and alcohol worsens it.

Alcohol gives false confidence: you think you drive better and take more risks.

You see signs and traffic lights, the sides and distances to other vehicles worse, and glare affects you more.
You coordinate movements worse and react later; you also decide worse or cannot carry out the decision.
It can also make you more aggressive or impulsive with other drivers.

You may not drive on drugs or any substance, prescribed medicine included, that impairs your fitness to drive safely.

A prescription is not enough: you must also remain able to drive with care, caution and attention.
Any substance that alters your state counts, sedative or stimulant: artificially raising alertness counts too.

The drug check uses a saliva test, not exhaled air.

If saliva cannot be taken for justified reasons, there is a medical examination or clinical analysis.
It covers every driver, cyclists included; other users only if involved in an accident or an offence.
No court order is needed: it is enough that the officer sees symptoms pointing to drugs.

Study topic 32 step by step: the rule, its citation and exam-style questions.