Much of the focus of drug-related driving is placed on alcohol and other illegal substances such as marijuana, but those are not the only type of drug that changes a driver's ability to operate the vehicle safely. Even simple and completely legal drugs can alter a driver's responses. Do you suffer from allergies? Antihistamines that treat this discomfort are one such drug that can cause dangerous side effects. . Antihistamines may target and relieve allergy symptoms, but they also target the central nervous system and cause sedation. Anything that reduces a person's reaction time can lead to serious car accidents. A recent study shows that while drug companies have done their best to reduce possible side effects, antihistamines still cause sedation and other dangers. The study suggests that the side effects of antihistamines vary widely between brands and sub-brands. Because the side effects can vary widely, drivers should test their body's reaction to individual antihistamines before ever getting behind the wheel. Treating allergy symptoms may not seem like a negligent behavior, but it can be considered one when a driver affected by the drugs puts others at risk by driving. If you are injured because a driver under the influence of antihistamines or any other drug -- whether over the counter or illegal -- causes a car accident, you may be entitled to compensation. Source: National Highway Traffic Safety Administration, "Antihistamines and Driving-Related Behavior," Aug. 22, 2012