How is marijuana used for health purposes?

There are three types of marijuana, Cannabis sativa, Cannabis indica and Cannabis ruderensis.  Marijuana was the most used medicine in history until the 1930s, when it was replaced by aspirin (after Beyer Pharmaceuticals discovered an inexpensive way to mass produce aspirin).  It is currently used most often as an anti-nausea treatment with chemotherapy for cancers and hepatic problems.  A multi-year research program in Great Britain by the Lancet (journal of the British Medical Association) has proven near-miraculous results with muscular paralysis patients.  It has been used successfully as a treatment for problems with the kidneys, the liver and the lungs.  Research indicates it slows or stops the growth of most lung cancers.  There has been a great deal of medical research in Britain, Germany, Spain and India, and it has been shown to be an effective treatment for Hepatitis C.  A 1997 survey of multiple sclerosis patients by Doctors Pertwee, Cosroe and others found that patients who smoked marijuana found significant relief for symptoms ranging from spasticity to anorexia, fatigue, balance problems, bowel problems and memory loss.

Although it does cause temporary problems (while "stoned") with short-term memory, neurological research has shown that long-term use of marijuana causes a massive increase in neurons in the pre-frontal lobe of the brain, where long-term memory, higher mathematical skills, and higher brain functions such as ordination and pattern analysis occur.  This does not prove it will make you smarter, but it will certainly not make you dumber.  Unfortunately, the artificial versions of the cannibinoids and higher THC isomers simply do not work nearly as well in clinical trials as the real thing.

The only real negative is that, after smoking a joint, heavy exercise is slightly more stressful on the heart than after a cigarette.  On the other hand, the marijuana effect goes away after 45 minutes, while the cigarette effect takes 48 hours to dissipate.  Wearing underwear causes a lower sperm count than smoking "pot."  There is no credible scientific evidence which indicates marijuana causes mental problems, although if you tend toward such getting stoned on anything is a bad idea.

The link below should help you find out more.  There are better sites, but some advocate smoking marijuana, which is illegal at the moment in the US.