Ask most musicians since the turn of the century what effect it has had on their music. With out it we would not have had Jazz, the Blues, Swing or Rock and Roll etc. Great musicians from Louie Armstrong to Whitney Houston have been caught using it. Cannabis suppresses the immune system of the body causing cancer. Not according to the UCLA, the Madrid University and several other studies, which indicate cannabis, can cure some cancers.
Cannabis can cause hallucinations.
Only at massive overdose levels but then again so does alcohol. However, an overdose of cannabis cannot kill, unlike alcohol. Cannabis aggravates schizophrenia and other mental disorders and undermines the effects of anti-psychotic treatment. Again so does alcohol. Many users though say the opposite is true and that it is an effective treatment for these disorders.