Posted: 8:30 a.m. | Updated 11:45 a.m.

Big changes are coming to medical marijuana in Colorado, after Gov. John Hickenlooper signed a bill into law today designed to limit bogus prescriptions for pot, among other things.

Nearly every medical pot recommendation from a doctor in Colorado is for severe pain, which works out to 93 percent of the 114,000 Red Card-registered Coloradans.  After that, and far less common: muscle spasms, with 16 percent. 

State data also shows that 65 percent of the approved applicants are male, with an average age of 42, and  56 percent of those on the registry live in the metro Denver area.

Now, state health officials are being told to develop guidelines for which patients actually deserve medical marijuana -- which is cheaper, and can be more potent, than recreational pot.

This new law also adds tighter restrictions on caregivers, who grow marijuana on behalf of patients. They are are not commercially licensed, so regulators fear they are a conduit to the black market. With the new law, caregivers are mostly limited to cultivating only 36 plants at a time. 

And, children with valid medical cards can now use marijuana on school grounds with the aid of a parent or medical professional.  But only if the school district allows it. The state registry shows that 467 patients are minors under the age of 18.