Psychological effects of marijuana

Marijuana affects both the mind and the body but this section looks at the psychological effects only.

For more information about the effects of marijuana on the body visit our physical effects of marijuana section.

So what does marijuana do to your brain?

There is a chemical in marijuana which is responsible for the ‘high’(euphoria) and hallucinogenic effects experienced as a result of using this drug.

This chemical is called tetrahydrocannabinol (THC). It is a psychoactive substance which means that it passes through the blood-brain barrier and alters brain functions such as memory, perception, mood and behaviour.

An example of this is an inability to remember something which happened only a short while ago.

They cause a range of symptoms/conditions which are discussed further in this guide. They include:

Visit any of these to learn more about potential long term effects on the brain.

Euphoria is a common effect of using marijuana but not everyone experiences this. Some people find that they experience anxiety, panic attacks or paranoia if they have eaten marijuana in food, e.g. ‘hash cakes’or have used strong varieties such as skunk.


Large doses, long term use or strong forms of marijuana result in a series of effects which are known as hallucinations. This is the name given to a state of altered reality in which someone experiences distorted time, sound and colour.

Sounds, colours and textures are sharper, clearly defined and exaggerated. Time appears to have slowed down or stopped altogether.

It is not uncommon to see and hear things which are not actually there.

These mind altering effects are not welcomed by everyone. Anyone who has a mental illness, is naturally anxious or has used a large amount of marijuana has a different and unpleasant type of experience.

They become anxious or panicky or feel that they are going to die. Paranoia is not uncommon and leaves the person feeling isolated and withdrawn.

There is also the issue of whether marijuana worsens a mental illness such as schizophrenia or increases the risk of developing psychosis especially if there is a family history of this.

But it has not been proven. More evidence is needed to show that heavy or long term marijuana use causes psychosis or other types of mental illness.

Examples of psychological effects of marijuana

Apart from hallucinations marijuana causes other psychological effects which include:

  • Poor short term memory
  • Problems with learning
  • Antisocial behaviour
  • Lack of concentration
  • Talkativeness
  • Elation
  • Lack of inhibitions
  • Anxiety
  • Panicky feelings
  • Paranoia

Everyone responds differently to marijuana. Some people experience a ‘high’followed by relaxation and drowsiness which is also known as ‘chilled’.

But, there are others who find that using marijuana causes anxiety and a sense of paranoia, especially if they have eaten it in food or ingested large doses.

This also happens to new users or people with a nervous disposition.

If you have a tendency to anxiety then you may find that marijuana worsens this. You may use marijuana as a relaxant but it can have the opposite effect.

Long term use of marijuana has a negative effect on many functions within the brain which includes the ability to learn and retain information.

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