8 Health Conditions That Can Affect Your Ability to Drive Safely
Discover the health issues that can slow your reflexes and judgment—and how to manage them to stay safe behind the wheel
Most motorists know—or should know—that being tired, emotionally distressed, or under the influence of drugs or alcohol means you shouldn’t get behind the wheel. But other health issues can also impact your ability to drive safely.
Some health problems are temporary, such as a bad cold that requires medication, impacting your motor skills and concentration. Others, including certain chronic conditions, can have more serious and lasting effects on driving ability.
Here are some common issues that can affect your ability to drive. While many of these are more prevalent with age, it’s the condition itself—not age alone—that determines driving safety.
Vision issues
Driving at night can be challenging for people of all ages, but it often becomes more difficult as we get older. Research shows that a 60-year-old typically needs up to three times more light to see clearly after dark than a 20-year-old. In addition, the eyes’ recovery time from glare—such as from oncoming headlights—declines with age, making night driving more stressful and potentially dangerous.
Contrast sensitivity, or the ability to distinguish objects from their background, can affect drivers of any age and can be affected by certain eye conditions or medications. During the day, drivers may have more difficulty seeing road markings or pedestrians in low-contrast situations such as fog or rain.
Common age-related eye conditions such as cataracts (which cloud the lens) and age-related macular degeneration (which affects central vision) can both significantly reduce a driver’s ability to judge distance, detect hazards, and read road signs. Glaucoma, which affects peripheral vision, can also interfere with safe driving.
The good news is that many vision problems are treatable or manageable. Regular eye exams—ideally every one to two years for adults and annually for older adults—can help detect issues early. If you notice changes in your night vision, glare recovery, or overall clarity, see your ophthalmologist promptly.
Diabetes
Diabetes can affect your ability to drive in several ways. Fluctuations in blood sugar levels—whether too high (hyperglycemia) or too low (hypoglycemia)—can cause symptoms such as sleepiness, dizziness, confusion, blurred vision, or, in severe cases, loss of consciousness or seizures.
Diabetes is also a common cause of peripheral neuropathy, a condition that reduces sensation in the limbs, especially the legs and feet. This loss of feeling can make it harder to judge pedal pressure accurately, increasing the risk of pressing the wrong pedal or applying improper levels of force while braking or accelerating.
To drive safely, people with diabetes should monitor their blood sugar levels regularly, follow their treatment plan, and avoid driving if they experience symptoms of hypoglycemia or hyperglycemia. Maintaining quick sources of glucose in the vehicle and undergoing regular medical checkups can also help ensure both overall health and driving safety.
Stroke
People recovering from a stroke may experience lingering problems with vision, judgment, coordination, and physical abilities—all of which can affect driving ability. Weakness or paralysis on one side of the body, slower reaction times, or changes in vision and perception can make it difficult to control a vehicle and respond to road situations.
Most people who have had a stroke are advised not to drive until cleared by a physician. Your doctor will likely recommend a medical evaluation or formal driving assessment to determine if it’s safe to return to the road. (These evaluations can be challenging since stroke survivors may revert to habitual driving behaviors even though they may no longer be able to fully analyze and appropriately respond to traffic situations.) Some individuals may need adaptive equipment or driving retraining, while others may be advised to stop driving permanently to ensure their own safety and that of others.
Cardiovascular disease
A study of commercial drivers with varying levels of risk for cardiovascular disease (CVD) found that those at the highest risk level were about twice as likely to be involved in a crash when compared to drivers with the lowest risk. Heart conditions can cause dizziness, fainting, or sudden loss of consciousness. Regular checkups and proper management of CVD are essential before getting behind the wheel.
Cognition
Driving requires an ability to process information quickly, think clearly, and make sound decisions. Cognitive decline can affect these skills, leading to confusion and poor judgment behind the wheel. Warning signs include an inability to recognize a location that should be familiar or struggling with traffic patterns that once felt routine. Cognitive testing can help determine whether it’s still safe to drive—or if it is time to hang up the car keys.
ADHD
Attention-deficit/hyperactivity disorder (ADHD) is characterized by inattention, hyperactivity, and impulsivity—and is linked to an increased risk of traffic accidents. However, studies show that appropriate treatment, including prescribed medication, can significantly reduce that risk and help ensure safe driving habits.
Sleep disorders
Sleep disorders can seriously impair a driver’s alertness and reaction time, with the errors made by drowsy drivers often resembling those of intoxicated drivers.
Fatigue tends to be worse during natural circadian lows, such as in the afternoon or late at night. Drowsy driving is estimated to cause at least 100,000 police-reported crashes each year, according to the National Highway Traffic Safety Administration. Anyone who experiences extreme daytime fatigue despite getting enough sleep should consult a doctor to rule out conditions such as sleep apnea or insomnia.
Normal aging
As we age, muscle tone and reaction time naturally decline. Power steering and modern braking systems can mitigate reduced strength, but slower reflexes can be hard to overcome. Our hearing capabilities also decline with age. Any of these changes can affect a person’s ability to drive safely.
Fortunately, many people with health conditions can still drive responsibly with the right precautions. Talk with your doctor about how your health—and any medications you take—could impact your driving. If you have a chronic condition, consider a driving evaluation with an occupational therapist who specializes in driving assessments. Doing so helps ensure not only your own safety but also the safety of everyone on the road.