Drugs tend to be classified according to their effects into three main groups.

Stimulants

The physical effects of these drugs included an over-stimulation of the nervous system creating energised muscles, increased heart rate, increased blood pressure and decreased appetite. A stimulant can cause heart, blood vessel and seizure problems, particularly if large amounts are used or if the user is extra sensitive.

A moderate dose of the stronger stimulants can make one feel more confident, outgoing, eager to perform, euphoric and excited. Larger doses or prolonged use of the stronger stimulants can cause anxiety, paranoia and mental confusion.

Drugs in this group include; Caffeine, Nicotine, Amphetamine, Cocaine / Crack, Anabolic Steroids, Amyl Nitrates and Ecstasy.

Depressants

The physical effects of these drugs include slowed heart rate and respiration, decreased muscular coordination and energy and a dulling of the senses. Downers can cause constipation, nausea and sexual dysfunction.

Initially, small doses can act like stimulants because they lower inhibitions, but as more is taken the overall depressants effect begins to dominate, dulling the mind and slowing the body. Downers can also induce euphoria, or a sense of well-being.

Solvents and Gases can cause dizziness, slurred speech, unsteady gait, and drowsiness. Solvents can be quite toxic to lung, brain, liver and kidney tissues, and some can lower blood pressure, causing the user to faint or lose balance. With small amounts of solvents, impulsiveness, excitement and irritability are common.

Drugs in this group include; Alcohol, Solvents, Gases, GHB, Barbiturates, Benzodiazepines, Opiates (Heroin, Morphine, Methadone, Narcotic Analgesics), Ketamine and Rohypnol.

Hallucinogens

These drugs can distort perceptions to induce delusions or hallucinations. The physical effects can cause nausea and dizziness. Marijuana increases appetite and makes the eyes bloodshot. LSD raises the blood pressure and causes sweating. Drugs that alter perceptual function overload or distort messages to and from the brain stem, the sensory switchboard for the mind, so that many physical stimuli, particularly visual ones, are intensified or distorted. Imaginary messages can also be created by the brain.

Drugs in this group include; LSD, Magic Mushrooms, Cannabis / Grass / Skunk and Ecstasy