Types of drugs

Drugs can be classified by how they impact the mind and body. For example, some drugs have a tendency to make a user active and energetic, while others make an individual feel relaxed and calm. There are four main classifications: downers, uppers, hallucinogens and inhalants.

Downers and uppers refer to how different drugs act on the central nervous system (CNS). In short, downers are depressants and uppers are stimulants.


These depressants slow down brain activity, creating feelings of relaxation and tiredness. Many of these drugs are prescribed for symptoms of insomnia and mental illness, but are very commonly abused because they may also create feelings of euphoria. Depressants are among the most highly addictive drugs, most dangerous and most likely to cause overdose. Examples of downers include:

  • Alcohol
  • Opiates (heroin, methadone, codeine and morphine)
  • Barbiturates
  • Benzodiazepines
  • Cannabis


The main use of these stimulants is to increase brain activity, energy, concentration and alertness. In the short term, uppers are believed to provide a ‘rush’, increase productivity and performance, while producing an excited high of pleasure. In the long term, they are incredibly addictive and have a very high potential for abuse. Examples of uppers include:

  • Amphetamine
  • Methamphetamine
  • Cocaine
  • Speed
  • MDMA


Hallucinogens alter the user’s perception of reality. They often result in auditory and visual hallucinations, known as ‘tripping’. Although hallucinogens are generally less addictive than other drug classifications, their immediate impacts are generally more severe and dangerous. Examples of hallucinogens include:

  • LSD
  • Magic mushrooms
  • Ketamine
  • PCP


Inhalants are chemicals that are ingested primarily by breathing them in. Most inhalants are commonly used materials that are not designed to be ingested by humans. Most produce feelings of a high. While they tend to be less addictive than many other substances, the use of inhalants is incredibly dangerous and causes many serious health effects. Examples of commonly abused inhalants include:

  • Paint thinner
  • Glue
  • Laughing Gas

Knowing the signs

Would you be able to spot whether your client or colleague was under the influence of drugs?

The signs and symptoms of drug misuse can be physical, cognitive and/or psychosocial.

Physical symptoms

  • Weight gain or loss
  • Apparent lack of interest in appearance and/or hygiene
  • Bloodshot eyes and/or dilated or constricted pupils (see below)
  • Frequent nosebleeds
  • Insomnia
  • Scabs, scars and other skin problems that may result from injection drug use
  • Dramatically increased or decreased energy.

Cognitive symptoms

  • Confusion
  • Disorientation
  • Impaired ability to make good judgement
  • Impaired ability to focus or concentrate

Psychosocial symptoms

  • Social withdrawal
  • Aggression
  • Mood swings

Constricted pupils

Constricted pupils
Associated with use of:

  • Heroin
  • Methadone
  • Opium
  • Codeine
  • Morphine

Dilated pupils

Dilated pupils

Associated with use of:

  • Cocaine
  • Crack
  • Speed
  • Amphetamines
  • LSD
  • Ketamine