When you should not get behind the wheel
You should not drive if you are drowsy, impaired by alcohol or drugs, or physically unable to control the vehicle. These are the three situations where driving becomes dangerous to you and everyone around you — and they are the ones you can assess yourself before you turn the key.
Drowsiness is harder to judge than most people think. You might feel alert enough, but if you have been awake for 18 hours or more, your reaction time is as slow as someone with a blood alcohol level of 0.05 percent. If you have driven for more than two hours without a break, or if you are fighting to keep your eyes open, you are too tired. Pull over, take a nap, or call someone else to drive.
Alcohol and drugs — including prescription medications and over-the-counter cold medicine — slow your reflexes and impair your judgment. If you have consumed alcohol, use a breathalyzer or wait until you are certain it has cleared your system. If you are taking a new medication, check the label for warnings about driving or ask your pharmacist. Do not guess.
Key Takeaways
- Drowsiness after 18 hours awake or two hours of continuous driving is as impairing as low-level alcohol intoxication, and you should not drive.
- Alcohol, prescription drugs, and over-the-counter medications can all impair driving ability — check labels and ask your pharmacist if you are unsure.
- Physical conditions like sudden dizziness, chest pain, severe pain, or loss of consciousness mean you should pull over when ready and call for help.
- If you have a medical condition that affects your ability to drive safely, your doctor can advise whether you should stop driving or take precautions.
- Vision problems, hearing loss, and mobility limitations do not automatically disqualify you, but they may require you to adjust how you drive or what vehicles you use.
Medical conditions that affect driving safety
Some health conditions make driving unsafe. Seizure disorders, uncontrolled diabetes, severe sleep apnea, and cardiac arrhythmias can all cause sudden loss of consciousness or control. If you have any of these, talk to your doctor before driving. Many states require doctors to report certain conditions to the Department of Motor Vehicles, and your doctor can tell you whether yours is one of them.
Conditions that come on suddenly — like a dizzy spell, chest pain, or severe pain anywhere — mean you should pull over when ready. Turn on your hazard lights, move to the shoulder if you can do so safely, and call 911 if the symptoms do not pass within a few minutes. Do not try to drive through it.
Chronic conditions like arthritis, Parkinson's disease, or stroke recovery may not make driving impossible, but they may require you to use adaptive equipment, take longer to react, or avoid certain driving situations. Your doctor can help you understand what is safe and what is not.
Vision and hearing problems
Vision is the most important sense for driving. If you cannot see clearly enough to read a street sign from 40 feet away, you should not drive until your vision is corrected. Most states require a visual acuity of at least 20/40 in each eye, with or without glasses or contacts. If you wear corrective lenses, wear them every time you drive — not just when you remember.
Cataracts, macular degeneration, and glaucoma can develop slowly enough that you do not notice the change. If your last eye exam was more than a year ago, schedule one now. Tell your eye doctor that you drive, so they can assess whether your vision is safe for it.
Hearing loss does not directly affect your ability to drive, but it can make you miss important sounds like sirens or horns. If you wear hearing aids, wear them while driving. If you have significant hearing loss in one ear, be aware that you have a blind spot on that side and adjust your mirror and head-check habits accordingly.
Medication side effects and driving
Many medications list drowsiness, dizziness, or blurred vision as side effects. If you take any of these, do not drive until you know how the medication affects you. Start with a short trip on a quiet road, not a highway or busy street. If you feel drowsy, dizzy, or your vision is unclear, pull over and do not drive again until the effect wears off or you switch medications.
Opioid painkillers, sedating antihistamines, muscle relaxants, and some blood pressure medications are common culprits. So are some antidepressants and anti-anxiety drugs. Check the label on every medication you take, and ask your pharmacist if you are unsure. If a medication makes driving unsafe, your doctor may be able to switch you to something else or adjust the timing of when you take it.
Age-related changes in driving ability
Older drivers often have slower reaction times, reduced flexibility in the neck and shoulders, and vision changes like reduced night vision or sensitivity to glare. None of these automatically mean you should stop driving, but they do mean you should adjust how you drive. Avoid night driving if glare bothers you. Leave more space between you and the car ahead. Take more time to turn your head and check your blind spots.
If you have noticed that you feel less confident behind the wheel, or if family members have expressed concern, talk to your doctor. Many communities offer driving assessment programs for older adults — your local Area Agency on Aging can tell you whether one is available near you. These programs test your actual driving ability in a real car, not just your reflexes in an office.
When to see a doctor about driving safety
Schedule an appointment with your doctor if you have had a recent change in your health — a new diagnosis, a new medication, a fall, or an accident. Tell your doctor that you drive and ask directly whether your condition or treatment affects your safety behind the wheel. Bring a list of all medications you take, including over-the-counter drugs and supplements.
If you have had a stroke, heart attack, or surgery, ask your doctor when it is safe to resume driving. Do not assume you can drive just because you feel well enough. Some conditions require a waiting period, and some require a formal driving assessment.
If you are unsure whether a symptom or medication is serious enough to mention, mention it anyway. Your doctor has seen this before and can give you a straight answer.
Frequently Asked Questions
What should I do if I feel drowsy while driving?
Pull over to a safe location as soon as possible. Turn off the engine, recline the seat, and nap for 15 to 20 minutes. If you cannot find a safe place to pull over, open the windows, turn up the radio, and pinch yourself — these are temporary fixes only. As soon as you can, stop and rest or switch drivers.
Can I drive if I take anxiety medication?
It depends on the specific medication and the dose. Some anxiety medications cause drowsiness; others do not. Check the label and ask your pharmacist. If the label warns against driving, do not drive until you have taken the medication long enough to know how it affects you, or until your doctor says it is safe.
Do I have to tell the DMV if I have a medical condition?
Some states require doctors to report certain conditions; others do not. Ask your doctor whether your condition must be reported. Even if it is not required, it is a good idea to tell the DMV if you have a condition that might affect your driving, because it protects you legally if you are in an accident.
What if I am not sure whether I am too tired to drive?
If you have to ask, you probably are. Drowsiness impairs your judgment, so you may not be able to assess yourself accurately. Call a friend, use a rideshare service, or wait until you have rested. It is not worth the risk.
Can I drive with one eye or one ear?
You can drive with one eye if your vision in that eye meets your state's minimum requirement, usually 20/40. You can drive with one ear — hearing loss does not disqualify you — but you need to be aware of your blind spot and adjust your mirrors and head checks. Talk to your eye doctor or hearing specialist about what adjustments you need to make.