10.4 Medical Fitness, Eyesight, Alcohol, Drugs & Diet
Key Takeaways
- A PCV entitlement is a Group 2 licence with stricter medical and eyesight standards than a car licence, requiring a D4 medical report and, from age 65, annual renewal.
- The drink-drive limit is 50 mg per 100 ml of blood in Scotland and 80 mg per 100 ml in England, Wales and Northern Ireland, but every UK bus and coach operator applies a stricter zero-tolerance policy.
- Nothing speeds up the elimination of alcohol: coffee, food and fresh air change how awake a driver feels, not their blood alcohol concentration.
- Ordinary over-the-counter cold and flu remedies frequently contain sedating antihistamines and are a recurring cause of professional-driver impairment.
10.4 Medical Fitness, Eyesight, Alcohol, Drugs & Diet
Objective 3.4 of the Driver CPC syllabus requires awareness of the importance of physical and mental ability, covering the principles of healthy and balanced eating, the effects of alcohol, drugs or any other substance likely to affect behaviour, the symptoms, causes and effects of fatigue and stress, and the fundamental role of the basic work and rest cycle. Section 6.3 deals with fatigue in depth. This section covers the rest: the medical standards that keep a vocational licence valid, eyesight, alcohol and drugs, and the diet and lifestyle factors that sit behind both.
The Vocational Medical Standard
A PCV (category D) entitlement is a Group 2 licence, and Group 2 medical standards are significantly stricter than the Group 1 standards that apply to a car licence. The reason is obvious: a bus driver is responsible for dozens of lives, for long periods, often in demanding conditions.
| Requirement | Position for a Group 2 PCV licence |
|---|---|
| Medical examination | A D4 medical report completed by a doctor is required when first applying and at renewal |
| Renewal frequency | Group 2 entitlement must be renewed periodically, with the interval shortening with age; from age 65 renewal is annual |
| Duty to notify DVLA | The driver must notify DVLA of any notifiable medical condition or any worsening of an existing one |
| Conditions that must be declared | Include epilepsy and seizures, diabetes treated with insulin or certain other medications, significant heart conditions, sleep apnoea and excessive sleepiness, serious visual conditions, strokes and TIAs, and mental health conditions affecting driving |
| Consequence of not declaring | Driving while medically unfit or failing to notify DVLA is a criminal offence and invalidates the driver's position entirely after any collision |
Obstructive Sleep Apnoea
This deserves its own note because it is over-represented among professional drivers and is directly linked to fatigue collisions. Excessive daytime sleepiness, heavy snoring, and waking unrefreshed are the warning signs. It is notifiable to DVLA, but it is also very treatable, and treated drivers routinely keep their vocational entitlement. The professional failure is concealment, not the condition.
Eyesight
| Standard | Group 2 requirement |
|---|---|
| Visual acuity | At least 6/7.5 (0.8) in the better eye and at least 6/60 (0.1) in the other eye, wearing glasses or contact lenses if needed |
| Corrective lenses | Permitted, but the corrective power is limited and spectacles must not have a power exceeding the prescribed limit |
| Visual field | A specified horizontal and vertical field is required, with no significant defect within the central area |
| If glasses are worn to drive | They must be worn at all times while driving, and a spare pair should be carried |
| Deterioration | Any significant deterioration must be reported to DVLA |
In a case study: a driver who realises at the start of a shift that they have left their prescription glasses at home cannot lawfully drive. The correct answer is always to report it to control and not take the vehicle, however inconvenient that is.
Alcohol
| Jurisdiction | Blood alcohol limit | Breath | Urine |
|---|---|---|---|
| England, Wales and Northern Ireland | 80 mg per 100 ml of blood | 35 microgrammes per 100 ml | 107 mg per 100 ml |
| Scotland | 50 mg per 100 ml of blood | 22 microgrammes per 100 ml | 67 mg per 100 ml |
These are legal maxima, not professional standards. Effectively every UK bus and coach operator applies a zero-tolerance policy, and a positive test at work is normally a dismissal and a Traffic Commissioner matter as well as a prosecution.
The Facts That Catch Drivers Out
- The body eliminates alcohol slowly — very roughly one unit per hour, and slower for many people. A heavy evening can leave a driver over the limit at 06:00 the next morning.
- Nothing speeds elimination. Coffee, food, a shower and fresh air change how awake you feel, not your blood alcohol concentration. They make an impaired driver a confident impaired driver.
- Alcohol and fatigue compound. A small amount of alcohol on top of sleep debt produces impairment far greater than either alone.
- Alcohol is a depressant that degrades reaction time, judgement of speed and distance, and peripheral awareness before the drinker notices any effect.
Drugs and Medication
The UK has specified limits for a list of controlled drugs, with very low limits for illegal drugs and therapeutic ranges for certain prescription medicines.
- Illegal drugs: near-zero limits. There is no professional context in which any use is compatible with holding a vocational entitlement.
- Prescription medicines: perfectly lawful to drive on if taken in accordance with the prescription and if the driver is not impaired. The medicines most likely to impair include strong painkillers, sedating antihistamines, sleeping tablets, some antidepressants and anti-anxiety medication, and some anti-nausea drugs.
- Over-the-counter remedies matter too. Ordinary cold and flu remedies frequently contain sedating antihistamines. Winter self-medication is a recurring and underestimated cause of professional-driver impairment.
- The professional rule: read the label, ask the pharmacist specifically "I drive a bus for a living — can I drive on this?", and tell your employer if you are prescribed something that may affect driving. If in doubt, do not drive.
Diet, Hydration and the Work-Rest Cycle
The syllabus names healthy balanced eating for a reason: shift work, limited breaks, and roadside catering combine to produce a diet that actively degrades alertness.
| Habit | Effect at the wheel |
|---|---|
| Large, heavy, high-fat meal before a shift | Post-meal alertness dip, which coincides with the natural early-afternoon circadian trough |
| Skipping meals then eating one large one | Blood sugar swings producing irritability and poor concentration |
| High-sugar snacks and energy drinks | Short spike followed by a sharper crash; caffeine can also disrupt the sleep that follows |
| Dehydration | A well-recognised cause of reduced concentration and headache; drivers often under-drink deliberately to avoid toilet stops |
| Regular, moderate meals plus water | Stable alertness across the shift |
| Physical activity on rest days | Improves sleep quality, which is the single biggest lever on fatigue |
The Work-Rest Cycle Is the Foundation
Everything above only works on top of adequate sleep. Drivers' hours and working time rules set the legal minimum rest, but the syllabus calls the basic work and rest cycle fundamental, and it is the driver's own responsibility to use rest periods for sleep. A legally compliant 9-hour daily rest spent awake is not rest at all.
The exam principle: any option that has a driver taking the wheel while impaired — by alcohol, by medication, by an undeclared medical condition, or without their prescribed glasses — is wrong, regardless of how much operational pressure the scenario applies.
A driver arrives for an early shift and realises they have left their prescription glasses, which are a condition of their licence, at home. What is the correct action?
A coach driver finishes a heavy evening of drinking at 01:00 and is rostered to sign on at 06:00. They feel fine after a shower and coffee. What is the professional position?
A driver is prescribed a strong painkiller by their GP that carries a drowsiness warning. What does professional practice require?