Delta-8, delta-9, THCA? What sets the different THC forms available in regulated cannabis products apart

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Aaron W. Harrison, Trinity University

(THE CONVERSATION) Hemp products have exploded across the United States, even in the majority of states where recreational marijuana remains illegal. This surge came after the 2018 Farm Bill removed hemp from the Controlled Substances Act and made cannabis products derived from hemp, defined as those containing less than 0.3% delta-9 tetrahydrocannabinol – commonly known as THC – legal. But the types of THC products available and the regulations around them, which vary by state, can be confusing.

A common question I get as a chemist is about the differences between the various delta THCs, and about the actual amounts of THC in the available products. There’s delta-8, delta-9, delta-10 and THCA. The amounts of THC in legally infused drinks and edibles also varies, with products most often containing 5 or 10 milligrams.

Knowing the difference between these compounds, and how much THC is in what you’re buying, goes a long way toward making informed choices as a consumer.

THCA and delta-9 THC

THC compounds are a subset of cannabinoids, which include any compound that interacts with the cannabinoid receptors in your body. THC is technically a family of compounds including delta-8, delta-9 and delta-10 THC, which all have similar chemical structures and are psychoactive – meaning they can alter your mood and perception and produce a “high.”

However, not all cannabinoids are psychoactive. For example, cannabidiol, or CBD, interacts with the same receptors, but through different mechanisms, so it does not produce a high.

9-tetrahydrocannabinolic acid, THCA, is the major cannabinoid found in the cannabis plant. THCA itself does not produce a high, however. It first needs to undergo a chemical reaction that generates a psychoactive compound: delta-9 THC.

These two compounds have different chemical structures. THCA has an extra group of atoms attached that must be removed to produce delta-9 THC. Under heat, this group breaks away from the rest of the compound, creating delta-9 THC. So, when the plant is burned or cooked, THCA transforms into delta-9 THC.

The 2018 Farm Bill measured only the delta-9 THC – not THCA – present in a hemp plant. So a hemp plant could have, say, 25% THCA and only 0.2% delta-9 THC and still be legal, as it has less than 0.3% delta-9 THC. But as soon as you heat it, the THCA will convert to psychoactive delta-9 THC.

However, in November 2025, the Agriculture Appropriations Act redefined hemp by limiting the total THC, including THCA, to 0.3% on a dry weight basis.

Changing regulations

This new rule will go into effect in November 2026 and significantly affect the potency of smokable hemp products. In the plant itself, the cannabinoids make up a large percentage of the flower’s dry weight. High-potency cannabis strains have THCA concentrations from 20% to 30% by dry weight – far above the 0.3% total THC threshold. This redefinition would effectively render the majority of these products illegal under federal law.

The math for edibles like gummies and seltzers is different, so the dry weight rule alone does not affect these products.

Consider a 12-ounce THC-infused drink: The total dry weight of the product would only need to be about 3.3 grams per 10 milligrams of delta-9 THC – a common higher-end dosage – to fall at exactly the 0.3% threshold. A 12-ounce can of seltzer weighs around 355 grams, so 10 milligrams of delta-9 THC in a 12-ounce drink easily passes the weight threshold.

Even a very small edible like a gummy easily meets this weight threshold. For instance, a single Starburst candy weighs 5 grams, well above the 3.3-gram minimum needed for a 10-milligram dose to be under the 0.3% limit.

To close this loophole, the new law adds a separate rule: Any final hemp-derived product containing more than 0.4 milligrams of THC per container is no longer legal. That’s well below a single dose of any commercially marketed THC beverage or edible.

However, the debate isn’t over. Lawmakers introduced amended legislation in April 2026 that will give states autonomy in hemp regulation as opposed to a blanket federal ban.

What about delta-8 and delta-10 THC?

Delta-8 and delta-10 THC are what chemists call isomers of the delta-9 THC. They have the same chemical formula but different chemical structures. It’s hard to even tell the difference looking at the molecules. One of the double bonds just shifts its position by one spot in the ring.

Like delta-9, delta-8 and delta-10 THC are also psychoactive and bind cannabinoid receptors in the body in a similar way.

While they do occur naturally in cannabis plants, the concentrations are far lower than THCA and delta-9 THC. For commercial products, they must be produced synthetically, which has raised concerns about chemical contamination from manufacturing.

Some evidence suggests that these alternate forms are less potent than delta-9, but scientists will need to conduct more research to determine whether that’s true.

These compounds fell outside the original calculation in the 2018 Farm Bill, which limited only delta-9 – effectively acting as another loophole. But the recently proposed total THC standard closes it by accounting for all types of THC. State legislation still varies substantially when it comes to hemp-derived products.

In April 2026, the Trump administration rescheduled medical marijuana from Schedule I to Schedule III. This move could potentially add to the regulatory confusion, but it will lower research barriers and help scientists address basic questions about THC’s potency, how the body metabolizes it and its therapeutic potential.

Underlying all these complex debates around the legality of hemp versus marijuana and recreational versus medical uses at the state and federal levels lies a single molecule: delta-9 THC.

This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/delta-8-delta-9-thca-what-sets-the-different-thc-forms-available-in-regulated-cannabis-products-apart-280008.