Combined with alcohol, the hazards of driving under the influence of marijuana are far more extreme than with either drug alone. Addiction is a complicated process that is described by tolerance, dependence and withdrawal. Users can develop a tolerance over time. People who smoke marijuana or who have a genetic predisposition might develop a tolerance and would need more of the drug. Withdrawal can occur after chronic use and may be mild due to the THC lasting longer in the body because it is fat-soluble.
Some people report irritability and restlessness and some have insomnia and nausea.
Heavy users however, can begin to show signs of dependence when they experience withdrawal symptoms. These symptoms include loss of appetite, problems sleeping, weight loss, and restlessness. This is highly controversial. It does appear that there are some valid medicinal uses for marijuana. Know the Facts Marijuana is not harmless, as some would have you believe, although it may not be as harmful as other drugs that are now legal.