Ask Your Pharmacist

September 09, 2021

My 72-year-old mother seems to be having trouble driving recently. She started on a new medication. Could that affect her ability to drive?


Prescriptions and over-the-counter medications can definitely affect your ability to drive safely. The potential for medications to impair driving ability can happen at any age, but their effects are especially important to consider as we get older.

Safe driving requires the ability to think clearly, focus attention, multi-task, use our senses to assess our surroundings, make timely decisions, and react when events in our environment change at a rapid pace.

Medications may affect our ability to drive because they may cause drowsiness, dizziness, blurred vision, decreased concentration, memory problems, or slow reaction time. The magnitude of these effects can vary greatly from person to person. I suggest your mother talk to her pharmacist about her new medication to see if this might be impairing her driving ability.

Examples of groups of medications that may impair safe driving are narcotics (i.e., hydromorphone, oxycodone, morphine) and benzodiazepines (i.e., clonazepam, oxazepam, lorazepam, diazepam, alprazolam), anti-seizure medications (i.e., phenytoin, valproic acid, lamotrigine, oxcarbazepine), antidepressants (i.e., tricyclic antidepressants, selective serotonin reuptake inhibitors, mirtazapine), sleep medications (i.e., zopiclone, melatonin, diphenhydramine) migraine medications (i.e., sumatriptan, rizotriptan), antihistamines (i.e. hydroxyzine, diphenhydramine), muscle relaxants (i.e., methocarbamol, cyclobenzaprine), cough suppressants (i.e., codeine, dextromethorphan), antipsychotics (i.e., risperidone, haloperidol, aripiprazole), and others.

Taking these medications and getting behind the wheel can be dangerous. For example, according to the Canadian Safety Council, a single dose of diazepam 10 mg (for anxiety) may produce more driving impairment than a blood alcohol concentration of 0.1 gram percent (the Criminal Code of Canada limit is 0.08 gram percent). The level of drowsiness caused by these medications is intensified when taken in combination with each other (i.e., taking a narcotic and a benzodiazepine) and taking them in combination with alcohol. Mixing medications with alcohol, cannabinoids, or street drugs, significantly increases your chance of dying in a motor vehicle accident.

Many New Brunswick seniors are on several medications for chronic health conditions. Some of these medications can negatively impact driving capability when used on their own or in combination with other prescription, herbal, or over-the-counter medications. Interactions between these medications, their effects on the body, and the length of time it takes the body to eliminate medications changes as we age. Visit the Canadian Safety Council for more information on these drugs

When you start taking a new medication, it is very important to know how to take it correctly and what to expect from its effects on your body. Even if you have been taking a medication for a long time, pay attention to the impact of medication on factors that impact driving. A change in dose of an antidepressant, even if someone has been on the drug previously, can have a significant impact on driving ability.

Talk to your pharmacist about the effects medications have on your ability to drive safely when you get a new prescription or over-the-counter medication. Pay particular attention to medications labelled “May cause drowsiness. Use caution when operating a car or heavy machinery” or “Do not drink alcoholic beverages when taking this medication”.

When taking medications to help you sleep, be sure to allow yourself a full eight hours of rest. If you do not have an adequate rest period, the medication will not have worn off by the next morning and you may not be able to perceive that your driving skills are impaired.

When your doctor or nurse practitioner adjusts your medication, choose a time period to start the newly adjusted dosage when you do not have to drive (i.e., the weekend or during a holiday).  Allow time for your body to adjust to the new dosage and to give you an opportunity to understand how the drug will affect your driving capability.

If you are starting new medications, or when there are dosage adjustments to medications, the safest thing to do is to plan another mode of transport until you can be certain you are not a risk to yourself or your fellow New Brunswickers, on the road.

Dr. Kevin Duplisea (PharmD BSc. Pharm, BSc. ACPR) is a pharmacist at Sharp’s Corner Drugstore in Sussex, New Brunswick. His opinions expressed in this newspaper are published for educational and informational purposes only, and are not intended as a diagnosis, treatment or as a substitute for professional medical advice, diagnosis or treatment. Send your questions to

Quispamsis pharmacist Kevin Duplisea dispenses information and advice on a wide range of pharmacy questions in a regular column published in several newspapers.

If you have a question you’d like to see answered in his column, you can send it to him at

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