Medical Fitness for Driving
The Effects of Illness and Temporary Impairment on Driving Ability

The Effects of Illness and Temporary Impairments on Your Driving Ability

Updated Dec. 11, 2020

Driving ability can be equally as impeded by a temporary physical or mental impairment as it is by ongoing medical conditions and permanent physical disabilities. Every person experiences an illness or injury at some time or another; the fact that you are usually fit to drive does not mean that you are always fit to drive.

People who suffer from permanent disabilities or debilitating health conditions are required by law to declare their impairments on their license applications and adhere to strict conditions every time they drive. Whereas, those who are experiencing a temporary impairment are personally responsible for deciding whether they are fit to operate a vehicle.

This is not a responsibility to be taken lightly. Getting behind the wheel when you are not fit to drive would put your life and the lives of other road users in jeopardy.

The effects of illness on driving

Any illness has the potential to make driving dangerous. An ailment does not have to confine you to bed for a week to hinder your reaction time and vehicle control skills. Your driving ability can be dramatically limited, simply by contracting a common cold. Even if you have a very mild cold or are experiencing a slight flair-up in allergies, it may be wise not to drive. Think, what could happen if you sneeze or cough at the wrong time? It only takes a momentary loss of physical control to cause a devastating accident.

Your cognitive function is likely to be impaired if you are not feeling well. Many common illnesses are known to create “mental fog”, where your brain’s ability to process visual and auditory information is hindered and your overall reaction time is extended as a result. Sick people frequently also experience slowed reflexes, general drowsiness and difficulty concentrating – a recipe for disaster when driving.

If you are feeling unwell or taking any medication that could affect your driving, the safest thing to do is stay off the road. Remember that driving can be a strenuous activity, particularly when you are not feeling 100 percent. Pushing yourself to drive when you should be resting is dangerous and may make your illness worse.

Driving with temporary injuries

Broken bones, sprains, sore muscles and connective tissue injuries will impair your ability to drive. Such injuries can cause significant problems when in the feet, ankles, wrists, knees, hips, back, shoulders or neck – all of which must be flexible and capable of exerting some strength, to operate a standard motor vehicle safely.

If you can sit comfortably with your injury, you may believe you can drive comfortably. Remember, driving involves considerably more physical actions than sitting does! You must be able to:

  • Press down on the pedals (injuries to the right leg or foot can make this extremely difficult)
  • Turn your torso and neck to see the rear and side of the vehicle
  • Steer, change gears, operate the parking brake and other controls

Do not drive if you cannot perform any of these actions without pain or significant discomfort. Always “test” your mobility in a safely parked vehicle before taking it out onto the road.

Medication side effects

All prescription medications have undesirable side-effects. These are “possible” effects, in that they may not occur in every person taking the drug, or on every occasion the drug is taken. Some side-effects are rare while others are fairly common and of course, they differ from one medication to the next. You must discuss any new medication (even a change in brand) with your doctor, to find out whether it could impede your ability to drive.

The common side-effects of many drugs include:

  • Tiredness or drowsiness
  • Nausea
  • Stomach cramps
  • Dizziness
  • Blurred vision

As you can imagine, any one of these symptoms striking while you are driving could spell disaster. You may be distracted by pain or discomfort, or your ability to assess the driving situation could be directly affected by drowsiness or blurred vision.

As side-effects do not occur in all patients, your doctor may advise you that you can drive UNLESS you experience certain undesirable side-effects. Take all medication as instructed by your doctor and do not drive if you are experiencing any side-effect which may impede your ability to operate a vehicle safely.

Driving and over-the-counter drugs

Medication does not have to be prescribed in order to be dangerous. Many over-the-counter cold, flu and allergy medications are known to cause drowsiness, dizziness and other side-effects that can hinder a person’s driving ability. These over-the-counter drugs include:

  • Decongestants
  • Antihistamines
  • Cough syrups
  • Pain relievers
  • Sleep aids
  • Acid relievers

Always read the label when taking an over-the-counter medication. Some products (many brands of mouthwash, for example) contain enough alcohol to raise a minor’s BAC above the legal limit! Even if an over-the-counter drug does not explicitly state that you cannot drive while taking it, motorists should avoid driving if the medication lists drowsiness or dizziness among its common effects.

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