You probably know that there are circumstances that can greatly increase someone’s risk of getting into a serious car crash. Being under the influence of drugs or alcohol is one such circumstance. Distraction is another factor that can increase someone’s collision risk.

There are a host of other potential risk factors, including exhaustion and inadequate maintenance of a vehicle, that can make one person far more likely to get into a serious crash than someone else. With all of these variables, one thing people often overlook is their current health. Do medical conditions have an impact on someone’s ability to drive safely?

There are statistics available about severe medical events and crashes

In an analysis of crashes involving known medical events by the National Highway Transportation Safety Administration, researchers found that 84% of those crashes involved an unpredictable and severe medical event, including diabetic reactions, blackouts and seizures. Strokes, heart attacks and hypoglycemic events could also cause someone to lose control of their vehicle and crash. Still, drivers crashing because of extreme medical emergencies only comprises about 1.3% of all reported crashes.

Other, more minor medical conditions like colds or the seasonal flu could play a role in someone’s crash. However, there are currently no statistics available regarding the implications of less severe medical conditions on someone’s ability to drive.

If you have noticeable symptoms, an illness probably affects your driving

Many people will try to go about their life as if everything is normal when they come down with a cold or the flu. Those with seasonal allergies that could last weeks or months may have no choice but to continue working no matter how miserable they feel. Unfortunately, a fever, headache or cough could be enough to increase your risk of causing a crash by decreasing your driving ability by as much as 50%.

For example, if you experience a sudden, sharp pain in your head, you could instinctively close your eyes, which could have significant consequences. A coughing or sneezing fit could cause someone to jerk on the steering wheel, potentially resulting in unsafe or unpredictable maneuvers that could end in a crash.

Even extreme fevers that don’t present other symptoms could leave someone at risk, as a high fever could eventually lead to a fainting spell or loss of consciousness, with all the dangers that entails on the open road. People too sick to drive should stay home. If you get into a crash with someone who seems sick, make certain that information gets included in the police report about the crash, as it could impact liability.