The active compounds
The cannabis plant contains many so-called cannabinoids. The two best known are THC and CBD. THC is responsible for the intoxicating effect; CBD is not intoxicating. In the fresh plant, THC is mostly present as THCA. It only turns into THC when heated.
Marijuana is the dried flowers; hashish is the pressed resin of the plant. How much THC they contain varies widely.
How THC works in the brain
The body has its own cannabinoid system, made up of messenger substances and docking sites called receptors. CB1 receptors are found mainly in the brain, CB2 receptors mainly on cells of the immune system.
THC binds to these receptors and takes over the role of the body’s own messengers. In the reward system, this indirectly leads to more dopamine being released. That explains the euphoric feeling and, at the same time, why cannabis can be addictive.
Where THC acts in the brain
- CerebrumThinking, planning, sensory impressions. THC disrupts how information is processed: attention and decision-making suffer, and symptoms of psychosis are possible.
- Limbic system with hippocampusEmotions and memory. THC can trigger anxiety and weakens short-term memory.
- Basal gangliaMovement and reward. THC raises dopamine levels, which can lead to dependence.
- CerebellumBalance, coordination and sense of time. THC can disrupt coordination and the sense of time.
- BrainstemBreathing, heartbeat, digestion. The pulse rises; with frequent use of large amounts, vomiting is possible.
What the effects depend on
- THC content: The more THC, the stronger the effect and the more often unpleasant effects occur.
- Amount: The risks rise with the dose.
- Form of use: Smoked or vaporised, cannabis takes effect quickly; eaten or drunk, much later.
- Physical and mental state: Mood, tiredness and health change the effect. People who feel low or anxious often experience this more intensely.
- Setting: Whether you are alone, with others, at a party or somewhere quiet makes a difference.
Many people experience relaxation and a lifted mood. Restlessness, anxiety, panic and distorted perception are just as possible, especially at a high dose or when in a poor state.
How long the effects last
Smoked or vaporised, the effect sets in almost immediately, is strongest after about a quarter of an hour and has largely worn off after two to three hours.
Eaten or drunk, THC is absorbed more slowly by the body. The effect comes on with a delay, often suddenly, and is hard to predict. Taking more because you cannot feel anything yet risks an effect that is far too strong.
Effects over time
Smoked or vaporised
- strongest after about a quarter of an hour
- largely worn off after two to three hours
Eaten or drunk
The effect comes on with a delay, often suddenly, and is hard to predict. Taking more because nothing can be felt yet can lead to an effect that is far too strong.
What happens in the body
Common physical signs are a dry mouth, red eyes, a faster heartbeat, dizziness and food cravings. Concentration, memory and reaction time decline during intoxication. This increases the risk of accidents on the road and at work.
How long cannabis can be detected
The effects wear off within hours; the traces do not. Breakdown products of THC can be detected in urine for about 30 days on average, and for considerably longer with regular use.
Effects and detection compared
Sources
- drugcom.de, a service of the BIÖG: Drogenlexikon, entry Cannabis
- The club’s health and youth protection concept, section on cannabis basics
- NIDA: Cannabis and the Brain