Drugs can affect your mind and body in several different ways. Driving under the influence of drugs is illegal, as it usually means your vision and concentration are impaired - leading to poor reaction times. For example, if you need to break suddenly or judge the braking distance of the car in front, it is unlikely your judgements will be accurate while you are on drugs.

Here is a list of the most common drugs used, and their affect on driving:

• Cannabis - impairs your concentration and co-ordination, meaning your reaction times and steering control will be affected. You may also feel a sense of paranoia and drowsiness, or have short-term memory loss. The effects of cannabis tend to last 2-4 hours, but if combined with alcohol the effects can be magnified.
  
• Cocaine - this drug is classified as a stimulant, and makes it harder for you to judge speed and distance. Cocaine can also make you feel over-confident, possibly leading to aggressive behavior towards other drivers. Cocaine can also make you feel alert for over an hour, however during this time your judgement is impaired.
  
• Heroine - this drug can cause you to feel tired, and impair your overall co-ordination. You are likely to feel euphoric during the effects of the drugs, but afterwards you may experience cramps, intense cravings and heavy sweating. The effects of heroine tend to last for 24 hours.
  
• Ecstasy - this is another stimulant drug that has hallucinogenic properties. This can lead to distortion of your vision and concentration. Ecstasy usually lasts for around four hours, and can make you feel nauseous.
  
• LSD - this is also a hallucinogenic drug that affects your senses, mainly your vision and hearing. It is likely you'll experience delusions while driving, as the effects of LSD last for up to 8-12 hours. Once the effects begin to fade you may experience panic and become emotional. Flashbacks can also be a side effect of the drug, occurring without warning up to a year after the event.
  
• Speed - this drug reduces your attention span, making it harder for you to react to changing driving situations. You are likely to experience headaches and have irregular heartbeats while on the drug, which usually lasts for 3-4 hours. As the effects of speed wears off you will generally feel anxious and have erratic mood swings, making you feel tired.
  
• Tranquillers - these drugs tend to make you feel tired, while affecting your co-ordination at the same time.
  
• Antidepressants (such as phenelzine) - these prescribed drugs can affect your driving, usually making you feel drowsy. Always confirm with your doctor or pharmacist that your prescribed medication won't restrict your ability to drive.
  
• Antihistamines - these drugs are usually used to treat allergies, such as hay fever, but can also be found in other medications, such as cough medicine. The main side effect of antihistamines is that they can make you feel drowsy. Antihistamines can also affect your vision and cause you to experience headaches. After taking the drugs for a few days, these effects may fade, but always check with your doctor or pharmacist if it is safe for you to drive when taking antihistamines.

Commonly prescribed medication, such as antibiotics or painkillers, won't have any affect on your driving.

Always ask your doctor or pharmacist if you are prescribed new medication, and are unsure if they will affect your driving ability. If in doubt, don't drive.