[Desired effects and adverse effects of cannabis use]

Although the use of cannabis shows no pronounced acute toxicity, acute psychological and psychomotor disturbances are observed occasionally after intake of single doses. Cannabis use can result in relevant impairment of driving ability. The risk is enhanced by concomitant use of alcohol. This augments the effect of cannabis significantly. After chronic use, significantly more psychotic symptoms become manifest, and there is a risk for developing psychological and physical dependence. Young age and pre-existing psychological disturbances increase the risk of these adverse effects. Chronic marijuana smoking is associated with increased toxicity and the risk of cancer of the respiratory tract. There is evidence of disturbance of the immune system and teratogenic effects of chronic cannabis use.