2 hours
Medications that impair driving
One in four prescription medicines can impair driving4 and many commonly used over-the-counter medicines may also lead to MR SID. Broadly, psychotropics (those affecting the central nervous system) and cardiovascular drugs carry the greatest risk of MR SID.
Three-quarters of drugs that impair driving belong to five classes: opioid analgesics, antidepressants, cardiovascular medications, antihistamines and sedatives. Other classes with examples are seen in table 1.
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Table 1: Main classes of drugs that increase risk of MR SID |
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Medication class |
Examples |
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|
Opioid analgesics |
Codeine Morphine |
Oxycodone Methadone |
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Antidepressants |
Citalopram Sertraline |
Fluoxetine |
|
Beta blockers and calcium channel blockers |
Atenolol Prazosin |
Diltiazem |
|
Antihistamines – sedating |
Promethazine/Phenergan Dexchlorpheniramine/Polaramine |
|
|
Antihistamines – “non-sedating” |
Loratadine Cetirizine/Zyrtec Fexofenadine/Telfast |
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Sedatives/ sleeping tablets/anxiolytics |
All benzodiazepines Zopiclone |
|
|
Antipsychotics |
Clozapine, risperidone, quetiapine |
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|
Anticonvulsants |
Gabapentin, sodium valproate, carbamazepine, pregabalin |
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|
Substance-dependence medications |
Methadone, buprenorphine, disulfiram |
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Antiemetics |
Prochlorperazine, metoclopramide |
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|
Hypoglycaemic agents |
Insulin, metformin, glipizide | |
Not every medicine within each class will impair driving, and not every person will be impaired. Unlike with alcohol, there is not always a linear effect between dose and impairment. It is also important for people to understand that the effects of a single dose may be prolonged. For example, the effect on driving performance of a single dose of zopiclone (used for the management of insomnia) is at least 11 hours after administration. Worse, the person may not be aware of their impairment since they have experienced a good night’s sleep.13
