Is Medical Cannabis safe? This study suggests it is. Much like with any other medicine some side effects are to be expected, when using Medical Cannabis. some examples of said side effects are drowsiness, dry mouth and dizziness. While such events may be unpleasent, they can be a small price to pay for pain relief and an increased quality of life. This study finds Cannabis to rarely have severe side effects and for other side effects to be mostly tolerable. In this study, patients maintained cognitive ability over 1 year, as well as pulmonary, liver, renal and endocrine functions. A conservative treatment of 2.5 g/d may induce pain relief while keeping patients safe.