What does cannabis do?

The effect of cannabis depends not only on its composition, dosage and mode of consumption, but also on the mood of the individual, on the individual's expectations, and on the atmosphere and setting. These factors explain why people experience different effects from cannabis. When cannabis is smoked, the active components are absorbed very rapidly via the respiratory tract and lungs, with an onset of action just a few minutes later. The effect peaks at fifteen minutes, subsides gradually after thirty to sixty minutes, and is largely finished after two to three hours. The proportion of substance active in the body depends greatly on the smoker's technique.

The active substances are absorbed by the body much more slowly when cannabis is eaten or drunk, and less of them reach the bloodstream. This is because of poorer absorption through the digestive system than in the lungs, and breakdown in the liver. In contrast to absorption through the lungs, in which the highest blood concentrations of THC may be achieved while the product is being smoked, when cannabis is eaten the blood concentration increases constantly over a period of four to six hours and a state of intoxication is reached later.

Immediate effects

The immediate effects of cannabis use are mild euphoria and relaxation, perceptual alterations including time distortion, and the intensification of ordinary sensory experiences such as those associated with eating, watching films and listening to music. When used in a social setting its effects may include the user becoming very talkative and subject to infectious laughter. There are also pronounced cognitive effects, such as impaired short-term memory and a loosening of associations, enabling the user to become lost in fantasy. Higher doses produce a general reduction in spontaneity, drive and involvement in the surroundings. Anxiety, confusion, aggressive feelings, (pseudo) hallucinations, nausea and vomiting have all been reported but are not usually experienced, although even long-term users may develop these reactions.

As the effects of THC subside, the individual often becomes drowsy and tired, but there is no "hangover" comparable to the effect experienced after heavy alcohol consumption. The physiological effects observed immediately after consumption are reddening of the conjunctivae of the eyes, a reduction in body temperature, a dry mouth and throat, hunger, a slightly elevated heart rate and blood pressure when lying down, and a drop in heart rate and blood pressure when standing. Heart rate may increase 20 to 50% over baseline. This occurs within a few minutes to a quarter of an hour and can last up to three hours.