Well I can tell-ya first hand Yes. It works. I'm an old burn out and used to do it as a kid, daily up until I was about 30 yrs old. Haven't done it in about 20 yrs until I met someone that was suffering from a Brain tumor and she smoked daily, because of suffering from Seizures. Smoking pot, for her worked to bring her Episodes down to about only 1 a month.
Anyways I'm a Chronic pain sufferer for over 10yrs now and have used opioid therapy to control my pain and to only bring it to an acceptable level.
I did smoke some and first off weed is a lot stronger now. A lot stronger. It works and works differently, than say taking a few pills, but still works
Here is a link to the lists of problems one has to have in Illinois to get the card
Well it was from Illinois.gov
Qualifying Debilitating Medical Conditions
What debilitating medical conditions make a patient eligible for the program?
• Acquired Immunodeficiency Syndrome (AIDS)
• Agitation of Alzheimer's disease
• Amyotrophic Lateral Sclerosis (ALS)
• Arnold-Chiari malformation and Syringomelia
• Cachexia/wasting syndrome
• Cancer
• Causalgia
• Chronic Inflammatory Demyelinating Polyneuropathy
• Crohn's disease
• CRPS (Complex Regional Pain Syndromes Type II)
• Dystonia
• Fibromyalgia (severe)
• Fibrous dysplasia
• Glaucoma
• Hepatitis C
• Human Immunodeficiency Virus (HIV)
• Hydrocephalus
• Interstitial Cystitis
• Lupus
• Multiple Sclerosis
• Muscular dystrophy
• Myasthenia Gravis
• Myoclonus
• Nail-patella syndrome
• Neurofibromatosis
• Parkinson's disease
• Post-concussion syndrome
• RSD (Complex Regional Pain Syndromes Type I)
• Residual limb pain
• Rheumatoid arthritis (RA)
Page 6
State of Illinois
Illinois Department of Public Health
Illinois Medical Cannabis Pilot Program
Frequently Asked Questions (FAQs)
• Seizures, including those characteristic of epilepsy (Starting January 1, 2015)
• Sjogren's syndrome
• Spinal cord disease, including, but not limited to, arachnoiditis, Tarlov cysts, hydromyelia, syringomyelia
• Spinal cord injury
• Spinocerebellar Ataxia (SCA)
• Tourette’s syndrome
• Traumatic brain injury (TBI)

Seems to be a longer list than most I've seen here and Aw ya the stuff cost a lot.