Drugs A drug is a chemical substances the effects the physical state of the body such as how the central nervous system (CNS) works. Drugs can be categorized according to weather there are legal or illegal or by the type of effects they have on the body for EG: stimulants EG: caffeine, cocaine, depressants EG: alcohol, solvents, pain killers EG: aspirins heroin. Stimulants speeds up the activity of the nervous system by neurotransmitters at certain synapses in the brain this caused. Increased alertness improved memory and endure revisal heart rate. Footballers and sports people take drugs because they need to be active. Parents take drugs to calm themselves down. People take drugs for medical reasons because they need to fight illness. Youths and teens take drugs take drugs to act cool in front of there mates.