Prescription drugs have awful side effects and can "kill" your liver.
People with MS who use marijuana say that they can replace several of their drugs (anti-spasticity, pain, muscle relaxers) with just the marijuana.
Actually, most folks with MS don't take regular narcotic pain killers for the pain, they take one of the anti-seizure meds like Neurontin or Tegretol because the normal pain meds don't help with neuropathic pain and the anti-seizure meds seem to help.