- Pain - Inflammation - Nausea - Seizures - Mood disorders - And more For many very ill people, medical marijuana is the one type of medicine that helps to relieve their pain and distress as well as treating symptoms associated with their medical condition, without hampering side effects. Marijuana has been shown to ease symptoms cause by a wide variety of serious medical conditions including but not limited to cancer, AIDS, and glaucoma. Medical marijuana is often an effective alternative to prescription synthetic painkillers.