Medical Cannabis is generally considered safe to use and its side effects are mild and are mostly tolerated by patients. However, it is important to know that in some cases there are more severe side effects, similar to other medications you choose to use. Side effects may include, dry mouth, Arrhythmia and changes in blood pressure, dizziness, changes in sugar levels in the blood, headaches or abdominal pain, trouble concentrating, thinking and in the perception of space and time.