Your allotment: one number, many forms
An Illinois patient's adequate supply is 2.5 ounces of usable cannabis per 14-day period, from an Illinois source. There is one combined limit for every product type, not a separate bucket for flower and edibles. A state explainer from CROO and IDPH puts it in capital letters: "THERE IS JUST ONE LIMIT, AND IT HAS NOT CHANGED."
| Product | Full 14-day allotment | Conversion |
|---|---|---|
| Flower | 70.87 g | 2.5 oz |
| THC concentrate | 21.3 g | 1 g concentrate = 3.33 g flower |
| Edibles | 21,300 mg THC | 100 mg THC = 0.33 g flower |
The state counts everything in flower equivalents. Someone who buys 10 g of concentrate has used about 33.3 g of the 70.87 g. If your practitioner thinks 2.5 ounces isn't enough, they can submit a waiver to IDPH for a larger allotment.
Flower, pre-rolls, vapes, concentrates, oils, edibles and beverages are all sold to patients. Minor patients are limited to infused products, which the caregivers and minors page covers.
Growing at home
Only registered medical patients may grow cannabis at home in Illinois, up to 5 plants, and additional restrictions apply. Adult-use consumers can't grow at all, which makes this one of the clearest reasons to hold a card. Since June 12, 2026, patients may also buy seeds from licensed dispensaries. The home grow guide walks through it.
One rule surprises people: medical patients may not give or gift cannabis to anyone, home-grown or bought.
Where you can't use it
The card doesn't open any public space. Illinois prohibits use:
- In any public place, meaning anywhere you could reasonably expect to be seen by others
- In any motor vehicle
- On school buses and school grounds, except as allowed under Ashley's Law
- In correctional facilities
- Near anyone under 18
Smoking medical cannabis is also banned in health care facilities. Private businesses and colleges may ban use on their property, and landlords may prohibit smoking cannabis on their premises. Local governments may authorize consumption lounges, so the legal places to use outside your home depend on where you live.
Driving
A registry card gives no protection for operating a car, aircraft or motorboat while impaired. State guidance says Illinois prohibits driving with 5 nanograms or more of THC per milliliter of whole blood within 2 hours of driving.
Transport has its own rule. In a vehicle, cannabis has to be in a reasonably secured, sealed container that's reasonably inaccessible while the vehicle is moving. The trunk is the obvious answer. The cup holder is not.
Need the certification first?
IDPH won't open your application until an Illinois practitioner certifies you. Book an online evaluation with a licensed practitioner; code DRWDY85872 takes 5% off. The practitioner, not the booking site, decides whether you qualify.
Book an Illinois evaluation →Work, guns and travel
The Act bars employers, schools and landlords from penalizing you solely for being a registered patient, unless federal law requires it. It also lets employers enforce drug-free workplace policies and act on specific, articulable signs of impairment. The employment page goes through what that means at work.
Gun owners need to read the FOID and medical cannabis page. Illinois State Police won't revoke a FOID for the card alone, but federal law is a separate problem.
Illinois doesn't accept other states' medical cards; visitors fall under adult-use limits, as explained on the out-of-state cards page.
A change coming November 12, 2026
Under Public Act 104-0463, consumable and topical products with more than 0.4 mg total THC per container become "cannabis" on November 12, 2026. From then on they may only be sold under the Cannabis Regulation and Tax Act, Illinois' adult-use cannabis law.
Before your first purchase
Know your 14-day window, keep your card with you, and plan where you'll store and use cannabis at home. If you're still weighing whether the card is worth having, the medical vs adult-use comparison sets the rules side by side. To find a store that sells to patients, use the state map on our dispensaries page.
Questions people ask
How much can an Illinois patient buy?
2.5 ounces of usable cannabis per 14-day period. That one limit covers all product types; 2.5 ounces equals 70.87 g of flower, 21.3 g of THC concentrate or 21,300 mg of THC in edibles. A practitioner can request a waiver for a larger allotment.
Can I smoke medical cannabis in my apartment?
Landlords may prohibit smoking cannabis on their premises, so check your lease first. Use is also banned anywhere you could reasonably be seen by others.
What is the Illinois THC driving limit?
State guidance says Illinois prohibits driving with 5 nanograms or more of THC per milliliter of whole blood within 2 hours of driving. A medical card gives no protection for impaired driving.
Can I give some of my cannabis to a friend?
No. Medical patients may not give or gift cannabis away.
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Sources
Last updated:
General information about Illinois law as of October 2026, not medical or legal advice; IDPH and the statute control, and a licensed practitioner decides whether you qualify.