There are several effects of heroin that affect the driver’s ability to drive safely. The first is drowsiness. The driver may simply fall asleep while driving that may lead to an accident. Another effect is reduced coordination. The driver is unable to manage his/her movements properly, so that will not be able to react quickly and properly. Another symptom is the symptoms of coming down and withdrawal. It is obvious that in these conditions a person cannot control himself that may be dangerous both for him and others.