Marijuana use has many negative effects on those that smoke or consume it. Its association with mental health disorders has been pretty well noted.  Persons who have a history of mental illness may find that marijuana exacerbate or worsens it. There is also some concern about whether or not marijuana causes schizophrenia and psychosis. It is not clear whether or not the drug causes these conditions or if it worsens them in those who already suffer from mental disorders. Individuals who have family members with mental illness or who personally have a history of it should steer clear of using marijuana.

Users are also at an increased risk of developing various cancers. This is due to the carcinogens inhaled when a person smokes marijuana. Infections of the lungs and reduced air capacity are also risks. Marijuana may also negatively affect the heart and persons with heart disease or other heart problems are more at risk for having a heart attack.

Memory and learning problems are also associated with long term and chronic use of marijuana. Individuals who have reportedly used marijuana for many years may end up having trouble recalling information. There cognitive skills may also be impaired.

Many people mistakenly believe that marijuana is a safe drug because overdosing is not fatal. Some individuals see it as mild and relaxing. While its use may help individuals feel relaxed, it is far from harmless. Individuals that use marijuana are at a risk for a number of things. If a person uses it for a long time or a lot of it, they run the risk of one day having memory and cognitive problems. They may not be able to remember things as well as they normally had. Other potential risks include depression, psychosis and schizophrenia. There is some debate about whether or not marijuana causes these conditions or just makes them worse. Cancer is another potential danger, especially of the mouth, throat and lungs due to the carcinogens found in marijuana smoke.

The development of a psychological addiction to the drug is also possible. An addiction to marijuana also makes some people feel unmotivated.  This may translate into employment problems. Chronic users often end up failing employee drug tests are unable to get a job or are forced out of ones that they already have. There are many dangers associated with marijuana use, some which are very serious.