Frequently asked questions How much cannabis can I possess in Illinois with an MMJ Card? In Illinois, you can possess the following amounts with a valid MMJ Card: – Up to 2.5 ounces of cannabis over a 14-day period. Patients may apply for a waiver in order to be allowed to possess more. – Concentrates: 500 mg of THC-infused products or 5 grams of concentrate for all Illinois residents, medical or not. – 250 mg of THC-infused product or 2.5 grams of concentrate for non-Illinois residents as of 01/01/2020.