Problems using marijuana (cannabis)

Short term

  • Difficulty concentrating
  • Impaired motor skills
  • Slow reflexes
  • Reduced coordination
  • Bloodshot or glassy eyes
  • Dryness of the mouth
  • Paranoia
  • Anxiety
  • Decreased motivation
  • Hallucinations

Long term

  • Dependence
  • Increased risk of respiratory illnesses (chronic bronchitis and lung, mouth, throat and tongue cancers)
  • Lowered sex drive
  • Impact on sperm count for males
  • Irregular menstrual cycles for females
  • Low birth weight babies
  • Memory loss
  • Learning difficulties
  • Lower educational attainment
  • Mood swings
  • Psychosis and psychotic symptoms
  • Suicidal thoughts

Problems associated with marijuana (cannabis) use are more common in those who first use at an early age and use higher doses for longer periods of time.

Marijuana (cannabis) use can also lead to deterioration in the condition of people with pre-existing mental illnesses and symptoms of schizophrenia.

As well as the serious physical and mental problems that marijuana (cannabis) use can cause, it can also lead to social and financial problems, poorer educational outcomes and the breakdown of relationships with family and friends.

Dependence on marijuana (cannabis)

When someone uses marijuana (cannabis) regularly they usually develop a tolerance for the drug. This means they have to use more to get the same effect as their brain has become used to functioning with the drug present.

One of the main symptoms of cannabis dependence is a loss of control over use. People crave the drug and find it difficult to stop using it.

If a person is dependent on marijuana (cannabis) and suddenly stops using it, they usually experience withdrawal symptoms, as their body readjusts to functioning without the drug. These symptoms usually last for less than a week, although people experience difficulties with concentration, memory and learning, plus problems sleeping for a longer period.

Marijuana (cannabis) withdrawal symptoms may include:

  • irritability, anxiety and nervousness
  • anger and aggression
  • loss of appetite
  • excessive sweating (particularly at night)
  • disturbed and restless sleep with strange nightmares

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This page was last reviewed in March 2014.