Cannabis is harmful  Studies have shown that cannabis may cause a number of physical and mental problems. It can cause respiratory problems, increase one's heart rate and lower one's sperm count. Cannabis use is also associated with causing or worsening some forms of psychosis. It has also been found to increase tiredness, depression and paranoia, impair short-term memory and hormone production and cause general cognitive decline1. As for cannabis' medicinal qualities, safer, more effective drugs are available. They include a synthetic version of THC, cannabis' primary active ingredient, which is marketed in the United States under the name Marinol. 1 Frank. (n.d.). Cannabis. Retrieved July 20, 2011, from Talk to Frank: