Is THCA Flower Legal in Illinois? (2025 Update)

THCA flower is likely illegal in Illinois under the state’s updated hemp laws. While the product remains available in stores and online, its legality depends on how Illinois interprets “total THC” in finished hemp products.

What Is THCA Flower?

THCA flower is raw hemp rich in tetrahydrocannabinolic acid (THCA). When heated, THCA converts into delta-9 THC—the psychoactive compound in marijuana.

In its natural state, THCA is non-intoxicating. Many users prefer it for potential wellness benefits without the “high” associated with THC.

How Illinois Defines Legal Hemp

Illinois uses a “total THC” standard to define legal hemp. This includes both delta-9 THC and the amount of THCA that could convert to THC after decarboxylation (heating).

To be legal, hemp products must contain no more than 0.3% total THC by dry weight. This stricter definition goes beyond the federal standard, which only measures delta-9 THC.

Why THCA Flower Is Likely Illegal in Illinois

Most THCA flower exceeds Illinois’ total THC threshold after heating. Even if delta-9 THC levels are below 0.3%, the high THCA content often pushes the total over the legal limit.

As a result, THCA flower is treated similarly to marijuana under Illinois law. Its hemp origin does not exempt it from regulation if it can produce illegal levels of THC when used.

Can You Still Buy THCA Flower in Illinois?

Yes, THCA flower is still sold in Illinois both in stores and online. Vendors often rely on federal definitions or third-party lab reports showing low delta-9 THC levels.

However, purchasing THCA flower carries legal risk. Illinois law considers total THC, including potential THC from THCA, not just what’s present at the time of sale.

Is THCA a Controlled Substance in Illinois?

No, THCA is not listed as a controlled substance in Illinois. The state’s Controlled Substances Act does not specifically mention it.

However, products with high THCA levels may be regulated due to their THC conversion potential. This means THCA flower could be restricted even if THCA itself isn’t scheduled.

Are There Possession Limits on THCA Flower?

Illinois does not set explicit possession limits for THCA flower. Because it’s not formally classified like cannabis, it isn’t bound by the same rules.

Still, possession may lead to legal consequences if the product exceeds total THC limits. Enforcement decisions may vary by jurisdiction.

How Federal Law Compares

Federal law allows hemp with less than 0.3% delta-9 THC by weight. The 2018 Farm Bill does not restrict THCA levels in finished products.

Illinois takes a stricter approach by including THCA in its total THC calculations. In any conflict, state laws take precedence in local enforcement.

Final Verdict: Is THCA Flower Legal in Illinois?

THCA flower is likely illegal in Illinois under the state’s “total THC” rule. While still available for purchase, most THCA flower exceeds legal THC limits after decarboxylation.

Buyers should verify lab results, understand local laws, and weigh the legal risks before purchasing. Legality depends not just on what's in the flower now—but what it can become when used.