Cannabis is a relaxant and may reduce a person's ability to react under pressure on the road. Cannabis also affects a driver's concentration and can make a person unsteady or give them blurred vision.
Cocaine gives people a false sense of security and can falsely heighten a person's perception of light and sound - key factors on the road.
Ecstasy makes people think they're better drivers than they are. This feeling of invincibility changes the way a person drives, making them a greater danger on the road.
Because of the distortion of sensory perception caused by LSD, driving is particularly dangerous. LSD causes the user to distrust the senses and can result in serious injury or even death.
The police are now skilled at recognizing signs of drug use. If you get caught while driving under the influence of drugs, the penalties are just as severe as those for drink-driving.
Medicinal drugs can impair your driving so please read the instructions and consult your doctor before driving if you are taking over-the-counter or prescription medicines.
Taking 2 drugs with the same effects, such as cocaine and speed, means the effects reinforce each other.
Mixing drugs with opposite effects such as alcohol and cocaine will have an uncertain effect on your brain leading to erratic and dangerous behaviour on the road.
The combined effects of 2 drugs taken together are more pronounced than each drug alone. Your tolerance for alcohol is reduced and the effects of cannabis significantly increased, meaning you have less control over the key decisions you make whilst driving.
Speed reduces your attention span whilst driving making you less likely to react to potential dangers, or stop where necessary.
It is an offence to be unfit to drive through drugs or alcohol. The Police can compel suspects to take part in a field impairment test or to supply a specimen of saliva or sweat to test for the presence of a drug.