Data from nearly 3,000 people between 65 and 79 years old who participated in the Longitudinal Research on Aging Drivers (LongROAD) study, revealed that nearly half of older adults who are active drivers take seven or more medications on a regular basis. In fact, a quarter of those reviewed were taking 11 or more medicines, and about 20% were taking potentially inappropriate medications with limited therapeutic benefit and an associated risk (e.g. first-generation antihistamines and benzodiazepines). As regards the risks associated with driving whilst using these medications, potential problems include blurred vision, confusion, fatigue and impaired coordination. The Automobile Association of America makes the claim that the use of medications like these can raise the risk of a crash by 300 percent. The most commonly encountered medications were cardiovascular drugs (73%) and CNS agents (70%). Prescribers in Australia and New Zealand rely on generic guidance from the document Assessing Fitness to Drive when determining the risk conferred my medications. A part of the text from this statement is reproduced below:

“Where medication is relevant to the overall assessment of fitness to drive in the management of specific conditions, such as diabetes,
epilepsy and psychiatric conditions, this is covered in the respective chapters. Prescribing doctors and dispensing pharmacists do, however,
need to be mindful of the potential effects of all prescribed and over-the-counter medicines and to advise patients accordingly. General
guidance is provided below.”

“General guidance for prescription drugs and driving”

“While many drugs have effects on the central nervous system, most, with the exception of benzodiazepines, tend not to pose a significantly
increased crash risk when the drugs are used as prescribed and once the patient is stabilised on the treatment. This may also relate to
drivers self-regulating their driving behaviour. When advising patients and considering their general fitness to drive, whether in the short
or longer term, health professionals should consider the the balance between potential impairment due to the drug and the patient’s improvement in health on safe driving ability. Other factors to consider:

• the individual response of the patient – some individuals are more affected than others
• the type of licence held and the nature of the driving task (i.e. commercial vehicle driver assessments should be more stringent)
• the added risks of combining two or more drugs capable of causing impairment, including alcohol
• the added risks of sleep deprivation on fatigue while driving, which is particularly relevant to commercial vehicle drivers
• the potential impact of changing medications or changing dosage
• the cumulative effects of medications
• the presence of other medical conditions that may combine to adversely affect driving ability, and
• other factors that may exacerbate risks such as known history of alcohol or drug misuse.”

There is also specific guidance provided about the effects of benzodiazepine, opioids, antipsychotics and antidepressants.