From the US Food and Drug Administration

If you’re taking a medication, is it safe to drive? Most likely, yes.

Still, before driving or operating other heavy machinery, the U.S. Food and Drug Administration advises you to make sure it is safe to do.

Although many medicines will not affect your ability to drive, some nonprescription (also called over-the-counter, or OTC) and prescription medications can have side effects that may make it unsafe to drive or operate other heavy machinery. Side effects can include:

• sleepiness/drowsiness 
• blurred vision
• dizziness
• slowed or uncoordinated movement
• fainting
• inability to focus or pay attention
• nausea
• excitability

Some medicines can affect your driving for a short time after you take them. For others, the effects can last for several hours and even into the next day.

In addition, some medicines have a warning to not drive any type of vehicle (for example, a car, motorcycle, electric scooter, boat, truck, bus or train) or operate other heavy machinery for several hours after taking the drug.

Medicines That Might Affect Driving

Knowing how your medicines — or any combination of them — affect your ability to drive or operate other machinery is an important safety measure. For example, some antihistamines and sleep medications work for longer periods than others. 

Some medicines that could make driving dangerous include:

• antipsychotic medicines
• antiseizure medicines (antiepileptic drugs)
• diet pills, “stay awake” medicines, and other stimulants (for example, caffeine, ephedrine, pseudoephedrine)
• medicines that treat or control symptoms of diarrhea and urine or bladder control
• medicines that treat or prevent symptoms of motion sickness
• muscle relaxants
• opioids, including some cough suppressants containing codeine and hydrocodone
• prescription medicines for anxiety (for example, benzodiazepines)
• sleeping pills
• some antidepressants
• some prescription and OTC cold remedies and allergy medicines that contain an antihistamine, nighttime sleep aids or cough medicines

Also, taking products containing cannabis or cannabis-derived compounds, including CBD, could make driving dangerous. CBD can cause sleepiness and changes in alertness.

Some Sleep Medicines Can Impair You, Even the Next Morning

People with insomnia have trouble falling asleep, staying asleep, or both. Many people take medicines before bedtime to help with their sleep difficulties. Come morning, though, some sleep medicines could make you less able to perform daily activities, including driving. 

If you take sleep drugs, talk with your health care professional about ways to take the lowest effective dose, when to take the medicines before bedtime, and when it would be safe to drive again after taking a sleep medicine. 

Allergy Medicines Can Affect Your Driving

Medicines containing antihistamines can help relieve many different types of allergies, including hay fever. But these medicines may interfere with driving. Antihistamines can slow your reaction time, make it hard to focus or think clearly, and may cause mild confusion even if you don’t feel drowsy.

Avoid drinking alcohol while using some antihistamines. Check with your health care professional about if it is okay to take antihistamines if you use sleep medicines. Those combinations can increase sleepiness or drowsiness. 

How to Avoid Impaired Driving

You can still drive safely while taking most medicines. Talk to your health care professional about possible side effects. Your health care professional might be able to change your dose, adjust the timing of when you take the medicine, or switch the medicine to one that causes fewer side effects for you. 

For nonprescription medicines, always follow directions for use and understand the warnings on the Drug Facts label. Take the medicine for the first time when you will not need to drive.

Before using your prescription medicine, follow the directions and the warnings on packaging, and read the FDA-approved labeling for patients and caregivers.

Tell your health care professional about all the medicines you are taking — plus any vitamins, and herbal or dietary supplements — and about any side effects you experience.