What is "it"?
The active chemical in cannibas is THC, Tetrahydrocannabinol. THC has mild to moderate analgesic effects, and cannabis can be used to treat pain by altering transmitter release on dorsal root ganglion of the spinal cord and in the periaqueductal gray. Other effects include relaxation, alteration of visual, auditory, and olfactory senses, fatigue, and appetite stimulation. THC has marked antiemetic properties. It may acutely reduce aggression and increase aggression during withdrawal.
Smoking Mary Jane is not necessary to enable its medical qualities, THC can be extracted and prescribed. So the canard of smoking it is quite false. It may be simpler and less expensive, but not required.