According to the World Health Organization, the term “drug” means any substance (excluding food and water) that physically or psychologically changes the way a person’s body works when it enters into the body. This definition includes drugs that affect a person’s mind as well as drugs that are medicinal in nature.

There are four main types of drugs:

  • Stimulants speed up the activities of the brain and increase heart rate and blood pressure
  • Depressants slow down the central nervous system and decrease a person’s level of awareness
  • Hallucinogens cause users to experience distortions in perception or sense and sometimes cause hallucinations
  • Analgesics can be sub-categorized into anesthetic drugs and non-anesthetic drugs and are mainly used to relieve pain

The Narcotics Division of the Hong Kong Government Security Bureau periodically publishes materials to help educate the public about different types of drugs. The drug information presented below is based on their publications.


Depressant and hallucinogen

Also known as "Special K" or "K", ketamine is a type of drug that depresses a person’s central nervous system giving the user the feeling that the mind is separated from the body. Its appropriate application is to anaesthetize animals while they undergo operations.

This type of drug usually comes in the form of a white powder and is packaged with coloured paper, but it can also come in the form of a colourless liquid. Ketamine is commonly snorted through the nose or swallowed as a tablet.

Some short-term effects of using ketamine:

  • Slurred speech
  • Hallucinations
  • Drowsiness
  • Nausea
  • Hypnotic feel
  • Inability to feel pain

Some long-term effects of using ketamine:

  • Nose bleeds
  • Depression
  • Memory loss
  • Damaged bladder function
  • Respiratory / heart problems
  • Impaired motor function
  • Deficiency in motor co-ordination and impairment of executive function
  • Physiological and psychological dependence


Stimulant and hallucinogen

The full name of this drug is methylenedioxymethamphetamine, or MDMA. Other common names include "E", "XTC" and "Adam". This drug gives the users a feeling of unlimited energy and so allows a person to feel energetic for lengthy periods of time. It usually takes the form of a round tablet and can come in many different colours. In Hong Kong, this type of drug is sometimes blended with other types of drugs, such as ketamine.

Some short-term effects of using Ecstasy:

  • Increased heart rate, over-heating of the body and higher blood pressure
  • Dehydration, sweating and exhaustion
  • Insomnia
  • Nausea
  • Paranoia
  • Involuntary muscle movement and teeth clenching

Some long-term effects of using Ecstasy:

  • Renal and liver failure
  • Depression and psychosis
  • Memory loss
  • Sudden death from respiratory failure
  • Neural cell damage
  • Physiological and psychological dependence


Depressant and hallucinogen

It is commonly found in the form of a dry plant or as a resinous pellet and it is usually mixed with tobacco before it is smoked by the user. The active ingredient in this drug is called delta-9 tetrahydrocannabinol, or THC. When THC enters a person’s body, it quickly reaches the blood stream and the brain.

Some short-term effects of using cannabis:

  • Confusion and anxiety
  • Distortion in perception
  • Become talkative, laugh easily and feel less inhibited
  • Reduced concentration
  • Physically inactive
  • Inability to balance
  • Dryness of mouth and throat


Some long-term effects of using cannabis:

  • Nervousness, irritability and short temper
  • Inability to concentrate
  • Memory loss
  • Depression and extreme suspicion of others
  • Decrease in motivation
  • Increased risk of respiratory diseases, such as bronchitis




Other common names for this drug include "C", "coke" or "crack". Originally made from the leaves of the cocoa tree, this drug is processed into an odourless, white flaky powder which dissolves easily in liquids. Cocaine is commonly snorted and stimulates the central nervous system.


Some short-term effects of using cocaine:

  • Reduction in appetite
  • Anxiety and panic
  • Overly talkative
  • Insomnia
  • Easily agitated
  • Narrowing of blood vessels
  • Increased heart rate and blood pressure


Some long-term effects of using cocaine:

  • Anxiety and mood swings
  • Tissue in the nose destroyed
  • Illnesses of respiratory or circulatory systems
  • Loss of appetite and weight
  • Sleeplessness
  • Impotence
  • Feel that they are being persecuted
  • Physiological and psychological dependence




Its proper name is Methamphetamine, and when taken it increases the activity of the brain and nerve impulses which travel around the body. It comes in the form of a semi-transparent, colourless crystal and is usually wrapped in plastic bags or aluminum foil packets.


Some short-term effects of using "Ice":

  • Restlessness
  • Insomnia
  • Reduced appetite
  • Sweating
  • Increased heart rate
  • Agitation
  • Anxiety and tension


Some long-term effects of using "Ice":

  • Nutritional disorders owing to depressed appetite
  • Chronic inability to sleep
  • Skin rash
  • High blood pressure
  • Irregular heart beat
  • Panic and confusion
  • Depression
  • Hallucination and feeling of persecution by others
  • Physiological and psychological dependence




Medically, these drugs are used to reduce anxiety and relax the body. However, drug users may develop a dependence on tranquilizers and end up increasing the dosage or by mixing it with other depressant drugs.


Some short-term effects of using tranquilizers:

  • Drowsiness
  • Slow down
  • Co-ordination impaired
  • Judgment impaired
  • Lower heart rate, blood pressure and shallow breathing
  • In large amount users can have slurred speech and black-outs, or even coma


Some long-term effects of using tranquilizers:

  • Depression
  • Chronic fatigue
  • Mood swings
  • Anxiety
  • Insomnia
  • Memory loss
  • Lack of motivation
  • Physiological and psychological dependence



Narcotic analgesic

Users of heroin use this to temporarily relieve pain. It acts as a sedative and is derived from opium poppy. Usually it comes in the form of a powder and can be inhaled through smoking or injected in the liquid form.


Some short-term effects of using heroin:

  • Initial euphoric feeling leading to being easily irritated by things
  • Incoherent speech
  • Retarded or sluggish movements
  • Pupil constriction
  • Overdose can lead to death


Some long-term effects of using heroin:

  • Damage to the immune system
  • Loss of concentration and memory
  • Loss of appetite and weight loss
  • Constipation
  • Cardio-vascular diseases
  • Shrinking of the vein (if the needle is poked at the same spot)
  • If needles are shared, increased risk of contracting diseases such as HIV
  • Physiological and psychological dependence


Cough medicine

People usually take this drug to relieve coughing. It is inexpensive and relatively easy to buy without medical prescription. The drug usually comes in the form of syrup and may even contain substances such as codeine and/or dextromethorphan. According to the Pharmacy and Poisons Ordinance, Cap. 138, it is an offence to illegally possess these two substances.


Some short-term effects of using codeine:

  • Confusion
  • Cold sweats
  • Reduced breathe rate
  • Dizziness and headaches
  • Hallucination


Some long-term effects of using codeine:

  • Tooth decay
  • Constipation
  • Lack of motivation
  • Memory loss
  • Brain damage
  • Physiological and psychological dependence


Organic solvents

Glue and thinner are the most common types of organic solvents. These usually come in liquid or aerosol form and are typically sniffed or inhaled by abusers.


Some short-term effects of using organic solvents:

  • Slurred speech
  • Dizziness
  • Hallucination
  • Suppressed breathing
  • Nausea or vomiting


Some long-term effects of using organic solvents:

  • Recurring and severe headaches
  • Chest pains
  • Liver and kidney damage
  • Heart and lung damage
  • Judgment impaired
  • Nervousness
  • Depression