Driving tests

Driving after taking medicine

Some medication can seriously affect your ability to concentrate, make quick reactions and judge other traffic

Some medication can seriously affect your ability to concentrate, make quick reactions and judge other traffic

At some point in your life you will take some medication. It might be for a headache or to alleviate the symptoms of a cold or virus, or it might be for something like high blood pressure. Certain types of medications affect our ability to drive and it’s illegal to drive while you are impaired so in this article we look at how you can tell whether you are allowed to drive after taking medication. If you want to know about illegal drugs click here, or alcohol click here.

There are two types of medicines:

  • Over-the-counter (OTC) – this is any medication that you can purchase from a pharmacy and it includes things like health supplements
  • Prescription – this is any medication that you need a prescription from a doctor for.

Some medications, even in small doses, can significantly affect your ability to operate a motor vehicle. The law is clear in that it states that you must not drive if you are impaired through taking any type of drug. This includes both legal drugs (medicines) and illegal drugs. If you want to read the legislation, it’s here.

List of prescribed medications that usually affect driving

There are specific types of medications which are more likely to impair your driving. These include:

  • Strong painkillers
  • Anti-psychotic medications
  • Depression medications
  • Epilepsy medications
  • Heart medications
  • Sleeping tablets
  • Allergy medications
  • Addiction treatment
  • Nausea medications
  • Anxiety medications

These drugs often have specific names which you may have seen before:

Sedatives, hypnotics or anti-anxiety agents

  • Barbiturates
  • Benzodiazepines
  • Zopiclone

Analgesics

  • Codeine
  • Narcotic drugs
  • Propoxyphene

Anti-allergy agents

  • Antihistamines

Antipsychotic and antidepressant agents

  • Tricyclic and similar antidepressants
  • Haloperidol
  • Phenothiazines

Anti-motion sickness agents

  • Antihistamines and related compounds
  • Hyoscine and related compounds

Some antihypertensive agents

Skeletal muscle relaxants

  • Dantrolene

Ophthalmic agents (topical preparations)

  • Most agents used for treating glaucoma

Some antimalarial medication

Drinking alcohol and taking medications

Consuming alcohol after taking medicines can magnify the effects of the medicine on your coordination, reaction time, sleepiness, and more. Even though you might be technically under the legal alcohol limit, you might still be impaired and therefore unable to drive.

What to ask your doctor if you are prescribed a medication

  • What are the general effects of this medication and how will they affect how I live?
  • Can I drive after taking this medication, and if not, how long do I have to wait after taking it?
  • Is there an alternative to this medication that doesn’t have as many side effects?
  • Can I make any lifestyle changes that would reduce my need for this medication?
  • Will the medication prevent me from doing my job? (this is important if you drive for a living)

How are medicines used

Medications are prescribed for a huge number of reasons. If it’s not possible for you to change your lifestyle to avoid taking them, or there is some kind of temporary or permanent physiology that means you need to take them to reduce symptoms, you will need to find an alternative to driving if you are prescribed meds that affect your driving. Common conditions that medications are prescribed for are:

  • Allergies
  • Depression, anxiety and schizophrenia
  • Flu, colds and viruses
  • Diabetes
  • Muscle spasms and muscle pain
  • High blood pressure, high cholesterol and heart disease
  • Degenerative diseases

You can also look into alternative medications rather than using pharmaceutical medications as they might have less side effects. Alternative medications are not guaranteed to have zero side effects, though.

How can medication affect your body?

Any drugs affecting the following skills might mean you can’t drive if you are taking them:

  • Spatial awareness – your ability to judge your position on the road and those around you
  • Concentration – your ability to maintain a focus on your driving
  • Coordination – your ability to steer and brake your vehicle
  • Vision – your ability to see dangers ahead and to correctly read the road
  • Hearing – your ability to hear things like sirens
  • Alertness – your ability to remain awake
  • Muscle power – your ability to control your vehicle
  • Reaction time – your ability to react in time to dangers
  • Judgement and perception of speed – your ability to judge where and how fast other road users are travelling in relation to your vehicle

If you feel any of the following symptoms after taking medicine, you are impaired:

  • Drowsy/sleepy
  • Nausea/sickness
  • Blurred vision
  • Being easily confused
  • Headache
  • Being unable to focus
  • Feeling weak
  • Unable to speak without slurring your words
  • Slowed reactions
  • Having trouble forming a sentence
  • Dizziness
  • Feeling wired and overconfident

Short term effects vs long term effects

Some medications only impair you while your body adjusts to the dose. For example you might only have to stop driving for several days until your body adjusts to it. You only have to find an alternative to driving for the time that you are affected by the medication.

Other medication has an effect every time you take it. Make sure you understand which type of medication you are taking – ask your doctor.

driver training

Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

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Posted in Advice, Car, Heavy Vehicle, Motorbike
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