NB! Drugs effects vary according to the psychological state and the health of the person concerned, the context in which the drug is taken as well as the quality of the drug and the quantity consumed.


The cannabis plant produces both dried flowers (“grass”, “weed”, “marijuana”) and resin (“hashish”, “hash”) which are usally mixed with tobacco for smoking. It can also sometimes be consumed in cake form (“space cake”), as chocolate, sweets or drinks. Certain countries recognise its therapeutic value.

It is a psychoactive substance which is:

  • illegal
  • natural
  • slightly hallucinogenic.

Desired effects

  • Euphoria, hilarity, feeling of wellbeing, increased sociability
  • Stress relief, sleepiness, daydreaming
  • Perception distortions (space and time), stimulation of senses.
  • Physical symptoms
  • Increase in heart rate and appetite
  • Pain-killer effect, anticonvulsant
  • Dry mouth, red eyes, vomiting

Immediate risks

  • Trembling, slowing of reflexes
  • Loss of memory
  • Lowering of blood pressure which can cause fainting
  • Hallucinogenic effects if taken in large doses
  • Paranoia, anxiety, panic, depression, psychosis, “bad trip” (rare)

Long-term effects

The risks are greater in those already suffering from psychiatric problems or persons with genetic predisposition, particularly psychoses or even schizophrenia. The long-term risks are:

  • psychological dependence: insomnia, anxiety, agitation
  • disorders of concentration and the ability to learn
  • amotivational syndrome (loss of motivation, apathy, depression, emotional numbing)
  • risks related to the tobacco, irritation of the respiratory tract, cancer of the lungs
  • possible damage to the immune system and to sperm
  • psychoses, schizophrenia.

Sciensano collects data and analyses the consumption of drugs, the drug market, the consequences for health, requests for treatment and the policies implemented with regard to drugs in Belgium.

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