Being legally allowed to drive is about more than holding a licence. On any given day you must also be fit to drive — sober, alert, medically able and seeing clearly. This is one of the most Ireland-specific areas of the test, because our drink-driving limits are lower than many countries' and are stricter still for new drivers.
Two alcohol limits, not one
Ireland sets the drink-driving limit by measuring blood alcohol concentration (BAC) in milligrams of alcohol per 100 ml of blood. Crucially, there are two limits:
- 50 mg for ordinary fully-licensed drivers.
- 20 mg — effectively zero — for learner drivers, novice drivers (the first two years after passing), and professional drivers (bus, truck, taxi, hackney and similar).
Twenty milligrams is so low that there is no "safe" amount to drink before driving. The only reliable approach for any new or professional driver is none.
Do not try to calculate how many drinks fit under a limit. Alcohol clears the body slowly — roughly one standard drink per hour, and slower still overnight — so the classic trap is the morning after: you can easily still be over the limit at breakfast after a heavy night.
What happens if you are caught
Penalties scale with how far over the limit you are, and are harsher for repeat offences:
- Since 2025, an ordinary licence holder caught between 50 and 80 mg faces an automatic three-month disqualification and a fine — there is no longer a points-only option at this level.
- Higher readings bring six-month, one-year or multi-year bans, larger fines, and in serious cases imprisonment.
- Novice and learner drivers are disqualified at just 7 penalty points, not the 12 that applies to full-licence holders — so a single drink-driving offence can end a new driver's licence outright.
Refusing to provide a breath, blood or urine sample when lawfully required is itself a serious offence, treated as harshly as a high reading.
Drugs — illegal and prescribed
Driving under the influence of drugs is an offence, and Gardaí use roadside drug testing. Two points people often miss:
- It covers prescription and over-the-counter medicines, not just illegal drugs. Some painkillers, hay-fever tablets, cold remedies and sleep aids cause drowsiness. Read the label, ask a pharmacist, and don't drive if a medicine warns against it.
- Combining a small amount of alcohol with medication can multiply the impairing effect of both.
Fitness beyond substances
You are also unfit to drive when:
- Tired. Fatigue slows reactions much like alcohol and can cause micro-sleeps. There is no cure but real rest — coffee and fresh air only postpone it. On a long drive, stop and rest.
- Eyesight fails the standard. You must be able to read a car registration plate at the required distance, in good light, with glasses or lenses if you need them. If you need correction to reach the standard, you must wear it every time you drive.
- A medical condition or its treatment affects your driving. Certain conditions must be declared, and you must be fit on the day — not driving while dizzy, in severe pain, or heavily medicated.
### Exam focus - BAC limits: 50 mg general, 20 mg for learner / novice / professional drivers. - Novices are disqualified at 7 penalty points (vs 12 for full licence). - 50–80 mg now = automatic 3-month ban for ordinary drivers. - The "morning after" can still be over the limit. - Drug-driving covers prescription and OTC medicines; check labels. - Fatigue's only cure is rest; you must meet the eyesight standard every time you drive.