Does smoking marijuana daily cause hallucinations and delusions or schizophrenia-like symptoms?
Smoking marijuana can cause psychotic-like symptoms of perceptual disturbances and suspiciousness in about one out of every seven people. So most people (six of seven) will not develop psychotic-like symptoms when they smoke marijuana.
People who have psychotic-like experiences independent of using marijuana will likely have these worsen if they smoke marijuana. Marijuana has been implicated as one factor among many which can contribute to the development of psychosis and schizophrenia, particularly in people who are vulnerable for psychosis based on their family history or have pre-existing psychotic-like experiences. It is estimated that about 7% of schizophrenia would not occur if there was no marijuana.