Guide to THCa

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THCa: The chameleon of cannabinoids.

If you’ve found this guide to THCa page, you’re likely a curious cannabis consumer who has heard the ever-increasing buzz around the cannabinoid du jour known as THCa. Congratulations on making it here because what we’re about to tell you is almost too good to be true. Indeed, THCa is an interesting cannabinoid not only for its potential to provide the same benefits as marijuana — minus the dubious reputation— but also for its unique position in the landscape of cannabis’ federal compliance guidelines.

So, if the rumors are true, and THCa can transform into something that gets you high (even really high), how could it be federally compliant? The answer is a nuanced one that requires the input of prominent cannabis attorneys in order to understand it fully. Keep reading to find out exactly what THCa is, why you may want to obtain it, and whether or not it might get you into hot water.

THCa in a nutshell

One of the hundreds of chemical compounds in cannabis, tetrahydrocannabinolic acid (THCa) is a cannabinoid acid. In other words, it’s the acidic form of THC. THCa is one of the many non-psychoactive cannabinoids in the cannabis plant [1]. 

Learn more in The Future of THC.

But wait. That’s only part of the story. It turns out that something quite extraordinary happens to THCa when it is heated. In short, it’s only non-psychoactive if it is unheated or in raw cannabis. So, does the presence of THCa in cannabis indicate that it is hemp or marijuana? No, what defines hemp and marijuana is the amount of Delta-9 THC that cannabis contains. Don’t worry if you’re confused. Who wouldn’t be? Bear with us while we explain.

Ultimately, the law considers cannabis products federally compliant as long as they do not contain more than 0.3 percent Delta-9 THC per dry weight. Federally compliant hemp is evaluated only on its Delta-9 THC levels [2]. 

Delta-9 THC and THCa have similar chemical structures yet different functions in the body. For example, THCa is a cannabinoid stemming from CBGA, the “mother of all cannabinoids,” which forms as the plant matures. Yet, because THCa has an extra molecular carboxyl ring compared to THC, the cannabinoid can’t bind to receptors to produce the same psychoactive effects as the THC high. But the chemical reaction that occurs when adding heat to raw cannabis changes the molecular structure of THCa to that of Delta-9 THC [1].

Is THCa illegal or legal?

Many people wonder if the legislative authors of the Farm Bills might have overlooked one small point, resulting in a happy accident for cannabis enthusiasts. That is, perhaps the legislators might have turned a blind eye to the fact that THCa becomes Delta-9 THC when utilized in particular ways through heat exposure. These suppositions aside, the convertible nature of THCa has become a topic of much debate as more people become aware of its psychoactive potential. 

As counterintuitive as it may seem, the THCa content of a federally compliant product like high-THCa hemp flower may, in fact, convert to the higher THC levels of its marijuana counterpart, but only if its temperature is raised sufficiently. Put simply, THCa only becomes potentially as psychoactive as marijuana when it is smoked, vaped, or cooked (versus using raw cannabis products), thus turning a federally compliant hemp product into something that could otherwise be considered a controlled substance. In this sense THCa has a unique double agency under the law.

But the million-dollar question is this: is this double agent we refer to as THCa a shady character we should worry about in a legal sense? Maybe, but only because it’s possible that law enforcement officials and/or legal representatives may misinterpret the law and erroneously label a THCa product with less than 0.3 percent Delta-9 as marijuana.

What’s important to keep in mind, is that THCa converts to Delta-9 THC when heated, yet retains the same legal status of its raw, unheated form if evaluated for the hemp market post-harvest. On the other hand, the same plant could be evaluated differently in the regulated marijuana markets and determined to be a marijuana plant because of its “total THC” content. 

These bizarre subtleties in the differences between how hemp and marijuana plants are evaluated could lead to scenarios where the same plant is labeled as both hemp and marijuana depending on who’s measuring it and when it is measured [3].

The Farm Bills and the legality of cannabis

After the 2014 Farm Bill removed hemp from the Drug  Enforcement Agency’s list of Schedule 1 substances, cannabis commercialization exploded. The Bill made hemp, which was designated as cannabis with 0.3 percent or less Delta-9 THC, federally compliant and allowed long-forbidden research to begin after almost a century of prohibition.

Expanding on this Bill, the 2018 Farm Bill allowed the production, sale, and consumption of hemp-derived products, making it clear to legal experts that all plant materials and substances derived from legally-defined hemp are federally compliant [4]. Hemp flower with high levels of THCa falls under this category. 

Federal law now defines cannabis plants with less than 0.3 percent concentration of Delta-9 THC on a dry weight basis as hemp plants and allows hemp production and consumption in all 50 states. In contrast, a cannabis plant with more than 0.3 percent Delta-9 THC per dry weight is defined as marijuana, which federal law still treats as a controlled substance on the DEA’s Schedule 1 list. Even so, some states allow medical use and/or adult recreational use of cannabis containing much more than 0.3 percent Delta-9 THC.

Learn more in Is hemp derived Delta-9 THC legal?

What’s the difference between THC and THCa?

The key distinction between THCa and THC is that THCa does not induce the intoxicating effects associated with THC. The natural THCa in a raw cannabis plant has cannabinoid acids that preclude any bond with the cannabinoid receptors in the human body that deal with psychoactive cannabinoids (see more on the endocannabinoid system below). Nonetheless, heat will convert THCa to psychoactive THC. This metamorphosis occurs when one of the carboxyl rings in the THCa is removed, thus enabling it to produce intoxicating effects by binding to the CB1 receptors in our bodies [5].

Regarding other types of therapeutic potential, THCa and THC overlap in some areas. Both cannabinoids have been associated with potential medicinal benefits, but more research is needed to know if they can help with nausea relief, better sleep, chronic pain relief or other issues.

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Is THCa the same thing as Delta-9 THC or Delta-8 THC when heated?

THCa is the acidic precursor to Delta-9 THC, the main intoxicating compound in cannabis.

Delta-8 THC, on the other hand, has the same number of atoms as Delta-9 THC, but their arrangements diverge, impacting their bond with endocannabinoid receptors. 

Delta-8 is also derived from its own version of THCa, called Delta-8 tetrahydrocannabinolic acid, but not much research exists to assess how its effects compare to Delta-9 THC.

However, both Delta-8 THC and Delta-9 THC have varying degrees of psychoactivity when consumed because they have changed from their acidic forms [8].  

What is THCa hemp flower?

In cannabis terms, the flower is the buds, or the main part of the plant that is harvested to use. THCa hemp flower is marketed to people who intend to smoke or vape federally-compliant hemp. This cannabis flower or bud is  processed from freshly harvested cannabis and is unheated. Though the product may contain high levels of THCa, these flowers contain only low levels of Delta-9 THC, rendering them federally compliant hemp as defined by the Farm Bills [4]. More specifically, the Delta-9 THC concentrations in THCa hemp flower must comprise less than 0.3 percent by dry weight.

Many cannabis consumers are surprised to learn that federally compliant THCa hemp flower has little or no difference from certain marijuana strains because of conflicting measurement guidelines between the regulated marijuana and hemp markets. For example, in certain medical marijuana and recreational marijuana markets, cannabis is measured for “total THC” versus being measured only for Delta-9 THC in other markets.

Cannabis attorney Rod Kight wrote in a recent assessment of marijuana in relation to THCa hemp flower, that certain flower could conceivably be sold as federally compliant hemp. The reason for these conclusions, he states, is because a strain’s Delta-9 THC level is often much lower than its THCa level. In the case of Durban Poison, the concentration of Delta-9 THC was only 1.24 percent but its THCa concentration was 22.15 percent, making it a very intoxicating flower if decarboxylated, ie. smoked, vaped, or cooked [3]. This flower would still not be federally compliant hemp, but shows the large difference there can be between the cannabinoids’ levels. 

Durban Poison’s potency potential, Kight says, is not atypical for various strains of marijuana flower. Advertisers of marijuana flower usually refer to “total THC,” of which THCa is often found in the highest concentrations. Although THCa does not have an intoxicating effect when eaten, the reason this total THC profile is acceptable to marijuana smokers, he asserts, is that THCa converts to Delta-9 THC when heated in a process called decarboxylation. Thus, smoking or vaping high THCa hemp flower will convert the cannabinoid to the psychoactive Delta-9 THC [3].

What about the USDA’s “total THC” requirement?

The potential fly in the ointment regarding the above analysis is that the US Department of Agriculture (USDA) requires that hemp must pass a pre-harvest test to make sure its total THC levels do not exceed 0.3 percent. The agency’s testing guidelines issued on January 15, 2021 state: “Tests shall measure the total THC concentration in a sample submitted to a laboratory for analysis. The laboratory will perform chemical analysis on the sample using post-decarboxylation or other similarly reliable methods where the total THC concentration level considers the potential to convert delta- 9-tetrahydrocannabinolic acid (THCA) into THC [7].” At first glance, this statement seems to be the final word on THCa legality, rendering pre-harvested plants with total THC levels higher than 0.3 percent Delta-9 THC after decarboxylation unlawful. But there’s more to the story.

Here’s where the legality gets tricky. The USDA’s “total THC” guideline only applies to hemp cultivation. Once it has been harvested and determined to be lawful hemp, there is no more USDA regulation, only DEA regulation, which only tests for Delta-9 THC, not total THC. The obvious question at this point is: how could the total THC of federally compliant hemp be higher than 0.3 percent if it has passed the initial pre-cultivation test by the USDA?

Here’s the answer: In contrast to USDA testing guidelines, the DEA only relies on the Delta-9 THC concentrations when determining its legal status, regardless of whether the plants passed the USDA pre-harvest total THC test. Thus, it is possible for hemp with high THCa concentrations to be deemed federally compliant, even if total THC passes 0.3 percent [3].

Effects and benefits of THCa

Fresh cannabis derived THCa does not produce a psychoactive high if consumed without “decarbing” it first (decarbing is a shortened version of decarboxylation). Even so, THCa has been associated with certain health benefits, though more research is necessary to determine if THCa can provide users pain relief or other medical advantages. [8]. 

Preliminary studies show promising potential for THCa’s neuroprotective qualities, however, more research is necessary to validate and confirm these initial findings [9]. 

Of course those looking for psychoactive effects from hemp will be more interested in what happens when high THCa hemp flower is decarboxylated. 

What’s the difference between THCa, THC, and CBD?

We’ve established that the main difference between THCa and Delta-9 THC is that the former is non-psychoactive unless decarbed, and the latter is psychoactive. Cannabidiol (CBD), on the other hand, is an entirely different cannabinoid with no psychoactive component. Having emerged into the cannabis market in recent years as a therapeutic cannabis superstar, CBD is associated with wide ranging benefits of its own.

What is the endocannabinoid system?

Most people know about body systems such as the nervous system or the lymphatic system, but fewer know much about the endocannabinoid system (ECS). The ECS is a network of chemical signals and receptors operating throughout the human body. Important for many aspects of human functioning, the ECS has a unique relationship with cannabis because of the relationship between the endocannabinoid receptors and the cannabinoids found in cannabis.

Receptors in our bodies get stimulated by our endogenous endocannabinoids: the molecules that have a structural likeness to molecules in the cannabis plant. These cannabis-like molecules affect our sensations, functions, and perceptions. Likewise, the effects of the cannabis plant occur when cannabis molecules (cannabinoids or phytocannabinoids) engage our bodies’ cellular mechanisms and link with the cannabinoid receptors [10].

CB1 and CB2 receptors are stimulated by either endocannabinoids (made by our body) or phytocannabinoids (made by plants). These receptors seem to influence neural activity in response to hunger, sexual desire, temperature, and other sensations. CB1 receptors mediate most of the psychoactive effects of cannabinoids, whereas CB2 receptors are associated with anti-inflammatory and immunosuppressive responses [10].

How to use THCa

Many cannabis consumers and patients use THCa (converted into THC) daily by smoking, dabbing, or vaping cannabis high in THCa. When used this way, THCa becomes a vehicle to reap the benefits of Delta-9 THC. Yet others find good reasons to use THCa for its own benefits before it is heated.

If your desired effects do not involve psychoactivity, eating raw cannabis is a great way to utilize THCa. Or, you may prefer juicing it or making a tincture out of raw cannabis. THCa tinctures and topicals can be taken as a regimen or used in a massage.

How to activate THCa

THCa is activated, and converted to THC, when it is decarboxylated, or in practical terms, when it is heated. The easy way to turn THCa into Delta-9 THC is to smoke or vape it. But these activities are not for everyone and can also lead to health repercussions. There are other ways to decarboxylate cannabis to make edibles, tinctures, and topicals such as baking your cannabis around 200-245 ºF for about half an hour. But be careful. If you bake it at 300ºF or higher, the heat will burn away its cannabinoids. Cooking it for too long will likewise degrade it [6].

Does THCa show up on a drug test?

The simple answer is yes. Both THC and THCa will show up on most drug tests. So, it’s best to avoid any heated or unheated THCa products for a period of time before taking a drug test [11].

Can I buy THCa hemp flower without inviting trouble?

Though THCa content is not considered by regulators once hemp is harvested, the issue is complicated and misunderstandings by law enforcement are easy to imagine. That said, if you purchase hemp products with less than 0.3 percent Delta-9 THC, the products should be federally compliant even if they have a high THCa content. However, it’s important to know your state’s local regulations before drawing conclusions.

Where can I find THCa?

Myriad cannabis dispensaries and boutiques carry high THCa hemp flower and other products with THCa. Reputable companies worth your patronage will provide you with a lab report detailing extensive breakdowns of what’s in your product. This report is known as a certificate of analysis (COA). and it’s packed with an alphabet soup of capital letters: THC, THCa, CBD, CBG, CBN, and many more. Each one is a cannabinoid that will have its amount listed on the COA. 

In many cannabis products, you’ll likely notice that THCa often has a much higher content than Delta-9 THC and other cannabinoids. That’s okay, but know that if you smoke, vape, or cook the product, it will turn to higher levels of the psychoactive cannabinoid Delta-9 THC.

Conclusion to the Guide to THCa

With respect to harvested hemp, the Farm Bill informs us that the only distinguishing factor between lawful hemp and unlawful marijuana is its concentrations of Delta-9 THC, not total THC. Yet, how these legal subtleties will play out as more hemp producers, sellers, and consumers educate themselves remains to be seen. But for now, many of us are thrilled to have access to this amazing cannabinoid. You can even buy THCa flower online for delivery right to your door!  

Though people continue to debate the idiosyncrasies of THCa legality, cannabis attorneys appear to be satisfied that high THCa hemp products are protected by the Farm Bill just the same as other hemp products.  For example, attorney Rod Kight asserts that post-harvested hemp plants with more than 0.3 percent concentration of total THC, (but less than 0.3 percent Delta-9 THC), are indeed federally compliant [12]. This is great news for people who seek the benefits of marijuana while still intending to comply with federal guidelines.

Medical Disclaimer / Legal Disclaimer – Information is provided for educational purposes. It does not and is not intended to constitute legal advice or medical advice. We attempt to be accurate and up-to-date, but the legality of cannabinoids and the science of cannabis are evolving. The author is neither a legal professional nor a medical expert. Before buying or using any products, you should check with your local authorities and medical providers


  1. Tetrahydrocannabinolic Acid
  2. H.R.2 – Agriculture Improvement Act of 2018
  3. THCa Flower – The Next Big Thing in Hempland
  4. HIA Position Statement on Delta-8 and Hemp Cannabinoids
  5. What Is THCa and Why Is It Different than THC
  6. What is THCa and What Are the Benefits of This Cannabinoid?
  7. Testing Guidelines for Hemp
  8. THCa vs THC – What Are the Differences?
  9. Tetrahydrocannabinolic Acid is a Potent PPARγ Agonist With Neuroprotective Activity
  10. Endocannabinoid System
  11. THCA vs. THC – More Different than You’d Expect
  12. Total THC and Harvested Hemp
  13. Δ9-Tetrahydrocannabinolic Acid Markedly Alleviates Liver Fibrosis and Inflammation in Mice
  14. The Role of Cannabinoids in Prostate Cancer – Basic Science Perspective and Potential Clinical Applications
  15. Cannabinoids As Potential Treatment for Chemotherapy-Induced Nausea and Vomiting

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Frequently Asked Questions

Yes, it is very likely that THCa could show up on a drug test. Drug tests screen for a wide variety of compounds. Though only a few cannabinoids possess psychoactive qualities, tests sometimes do not know the difference between THC and THCA molecules.

Yes, THCa is a primary cannabinoid.

Yes, THCa is non-psychoactive and non-psychotropic. Yet, when it is heated, it is turned to Delta-9 THC, which is psychoactive and psychotropic.

The cannabinoids will degrade and lose their potency.