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What Is THCa In Cannabis & How Does It Work?

Dr Abraham Benavides


Dr Abraham Benavides

Medical Doctor

When it comes to cannabinoids, THC gets all the attention. But THC wouldn’t exist without its progenitor: THCa.

This little known inactive compound contained in the trichomes of raw cannabis is a fundamental reason we get high when we smoke weed or light up a joint. 

Before THC becomes THC, it’s actually THCa. So if you want to get technical, it’s actually THCa we’re looking for (not THC) when picking the perfect eighth for recreational or medical use. 

Interested in learning more about THCa? 

Keep reading to unravel the mysteries behind this extremely important cannabinoid compound.

tetrahydrocannabinolic acid

What Is THCa? 

Contrary to popular belief, THCa is most certainly not an inactive cannabinoid. Short for tetrahydrocannabinolic acid, THCa is the acidic form of THC.

THCa was discovered in 1965 by German professor Freidhelm Korte who was examining the contents of hashish. 

It’s essentially the immediate precursor to THC. Without THCa, THC wouldn’t exist and we wouldn’t get high when we smoke cannabis. Researchers estimate that up to 90% of the plant’s THC contents are from THCA.

In its raw form, THCa is non-psychoactive. So consuming fresh THCa will not produce intoxicating effects. However, it does work on other receptors in the body – just not the ones that will get you high.

When it comes to their chemical structure both THC and THCa are nearly identical. THCa has one more carboxyl acid chain than THC. This acid chain is what prevents THCa from giving mind-altering effects we commonly associate with cannabis. 

Interestingly, THCA comes in two “isomers” or forms: THCA-A and THCA-B. Little is known about the differences between them or their balance in the plant, however, they both eventually turn into THC upon decarboxylation. The current understanding is that THCA-A is the predominant form of THCA in a plant.

THCa is derived from CBGa (cannabigerolic acid), which is considered the “original” compound of cannabis. You’ll often hear CBGa referred to as the “mother cannabinoid.” This OG cannabinoid is the foundation for three major compounds: CBDa, CBCa and of course THCa.

These eventually turn into the other well-known cannabinoids we’re familiar with: CBD, CBC, and THC. CBGa is the precursor to THCa. So in a way it’s also responsible for getting us high as it gives way to THC.

The cannabinoid that comes after THC is degraded is called CBN, which is non-psychoactive but retains two properties similar to THC: increased appetite and sleepiness.

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Is THCa Psychoactive?

No. THCa is a non-intoxicating cannabinoid. This means THCa does not cause a high like THC does, but can still influence your brain chemistry, inflammation, and mood in other positive ways. 

THCa’s unique molecular structure does not bind strongly to CB1 or CB2 receptors. Research shows that THCa binding affinity to CB1 receptors is approximately 60 times weaker than THC! 

Seeing that THC’s binding affinity to CB1 receptors is what causes us to feel high, it makes sense that we don’t experience mind altering effects when we consume THCa. 

Although the cannabinoid acid doesn’t bind to cannabinoid receptors, it does bind at several anti-inflammatory receptors, such as PPARy, GPR55, and COX-1 and 2, which is why the compound is suggested to positively influence things like mood and inflammation.

Does It Get You High? 

Yes, but not in its raw form. THCa must be heated to a certain point to become psychoactive. When THCa is heated, it’s then converted to THC. Ultimately, this is how THCa will get you high

This conversion process is called decarboxylation. Aside from using a decarboxylation machine, some of the most common ways to decarb THCa and turn it in to THC include: 

  • Cooking cannabis flower in the oven at low temps
  • Smoking cannabis flower in a bowl, joint or blunt
  • Exposing cannabis to sunlight
  • Vaping cannabis flower 

Decarboxylation makes THCa change shape by eliminating its extra carboxyl group. When the additional acid group is gone, the new shape fits better into the body’s CB1 and CB2 receptors.

Basically, this is how we get high from weed. Once decarbed, the acid group in THCa is dropped and it becomes the familiar cannabinoid we all love for getting us high. 

Interestingly, THCa comes in two “isomers” or forms: THCa-A and THCa-B. Little is known about the differences between them, but both eventually turn into THC upon decarboxylation. Currently, it’s understood that THCa-A is the predominant form of THCa in a plant.

tetrahydrocannabinolic acids

What’s the Difference Between THC and THCa? 

Did you know that cannabis contains over 150 cannabinoids

THC is the main intoxicating and psychoactive cannabinoid of the entire lot. It produces euphoric and inebriating effects we associate with weed. THCa does not. 

THCa in its raw form will not get you high. This is because THCa  binds ineffectively to the CB1 receptors in the brain. THC, however, has a strong binding affinity to CB1 receptors.

THC is the psychotropic form of THCa. They are both “psychoactive” in the sense that they can influence our mood and wellbeing. These terms are still evolving. The biggest difference is that THC causes intoxication and THCa does not. 

The major difference between the two cannabinoids are the shapes of the molecules. THCa has an additional carboxyl group making THCa an acid. And this makes all the difference of how the cannabinoids influence the way we feel. 

Contrary to popular belief, the trichomes in cannabis flower contain THCa, not THC. THC only exists in very small quantities in raw cannabis.

Related Reads: THCa Dabs, THCa Drug Test, THCv VS THCa, THCa Vape Carts, THCA Pre Rolls

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THCa Effects

Since THCa is non-intoxicating, consuming it in its raw form will not produce any noticeable effects.

That said, once THCa is decarbed it turns into THC. So when THCa is heated, it will essentially produce the same intoxicating effects we associate with THC. 

In my own experience, the effects I feel from consuming THC largely depend upon the type of cannabis I consume. For example, sativa strains tend to give me a boost of energy, enhance my mood and produce euphoria. I talk more about this in the THCa flower review.

Indica on the other hand tends to make my uber relaxed, happy and sleepy. My social inhibitions often lessen. 

That said, there’s new research that suggests the common “sativa vs indica distinction” actually relies on a plant’s terpene profile rather than its cannabinoid profile.

Anecdotal evidence of the effects of THCa varies. 

  • In one subreddit, a user depicts the effects of consuming raw THCa. They describe it as being a slightly psychoactive brain and body high that takes significantly longer to take effect than THC. 

When smoked, the user reported THCa to minimize negative side effects such as anxiety. 

  • Another public opinion of THCa went against the grain. This user said that high THCa flower does produce the same effects THC does. The high from THCa flower was mild enough to still function. 

Much like THC, the effects of THCa seem to affect people differently based on their own body chemistry.

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THCa Benefits 

While more research is definitely needed,  so far THCa appears to have some very promising therapeutic potential. 

Personally, I’ve tried both THCa flower and concentrate. In my experience, THCa reduced my anxiety and provided much needed stress relief. I suffer from anxiety so when I’m excessively worried THCa has done the trick so far. 

Though not confirmed by science, I’ve also found THCa to be pain-relieving. When I have a sore back from sleeping wrong or poor posture, I take a dab of THCa. Just one dab makes the pain dull or disappear depending on how severe it is. 

There’s also some anecdotal evidence of the benefits of THCa.. 

  • In a subreddit about the effects of THCa tinctures, one user claimed THCa to help with nausea, pain and sleep. 
  • On the other hand, another user posted that smoking THCa caused some anxiety: 

As with any cannabinoid, all experiences are not the same. It depends on the quantity ingested, percent decarboxylated, how our bodies processes THCa or any compound for that matter. 

There has been some scientific research conducted on THCa. According to various studies, THCa may contain the following possible therapeutic benefits: 


In a 2017 study, THCa was shown to provide superior treatment to patients suffering from inflammatory bowel diseases (IBDs) than CBD. THCa was suggested to be an antagonist that markedly reduced inflammation. 

In the study, THCa appeared to actually increase the lifespan of human colon cells. The authors of the study went so far to suggest that THCa should be used in place of CBD for IBDs. 


Research on the anti-nausea effects of THCa found that THCa significantly reduced vomiting in animal models. Researchers of the study suggested that THCa was more effective in reducing nausea and vomiting than THC. 

This means that smaller quantities (doses) of THCA may be needed compared to THC for nausea and vomiting relief. THCA may work better than CBD or THC alone for anticipatory anti-nausea effects as well.


In a 2017 study, researchers examined the neuroprotective effects THCa had on mice. THCa was shown to be more effective at preventing neurodegeneration and improving motor skills than other decarboxylated compounds.  

Researchers went so far to suggest that THCa should be considered as a viable treatment of neurodegenerative and neuroinflammatory diseases such as Huntington’s disease. 

THCA also displays anticonvulsant properties, making it potentially useful in seizure disorders. Early research indicates it may be ten times more effective than FDA-approved Epidiolex (pharmaceutical CBD) at reducing seizures.

Reducing Adiposity

A recent 2020 study found THCa to be a selective PPARγ (receptors that control fatty acid storage and glucose metabolism) modulator in mice. Researchers suggested that THCa had the potential to prevent metabolic syndrome and inflammation caused by obesity. 

Inhibit Cancer Growth

An extensive 2006 study found that six major cannabinoids, including THCa, had antitumor properties. While the overall data was scarce, THCa was shown to inhibit cancer cell proliferation in human breast and prostate cells. 

In particular, cannabinoids such as THCa were suggested to produce anti-inflammatory activity that also slowed the growth of colon cancer cells in a lab.

Inhibit Tumor Necrosis Factor (TNF) 

Research has also discovered that raw THCa may also inhibit TNF, a substance in the body that causes inflammation. The reduction in TNF levels caused by THCa also appeared to last for an extended period of time with greater efficacy than THC.

THCa Side Effects & Risks

The side effects of consuming THCa aren’t well-documented. Since THCa hasn’t been researched in depth, there’s still a lot to learn about the cannabinoid. 

We can assume that THCa that is decarboxylated and turned into THC will have similar side effects. Research shows that there are some acute and long-term negative side effects associated with THC consumption. 

Some of the  risks and side effects associated with THC consumption include:

I’ve personally experienced both an increase and decrease in anxious feelings when consuming THC.  Some strains seem to cause more worry than others. In terms of sleep, most cannabis ultimately makes me drowsy. Overall, I’ve found that hemp helps me achieve deep sleep.

Wrapping Up THC-A

THCa definitely deserves some solid recognition. Considering we wouldn’t get stoned without it, THCa is one of the most important cannabinoids that exists. It even contains some impressive therapeutic properties.

THCa’s potential seems promising, but more research needs to be conducted, which is typically the case with most things cannabis. That said, the future looks bright for the acidic precursor to THC. 

We know that THCa is the foundation of THC. And as such it deserves praise for gatekeeping the cannabis  hallmark of psychoactivity we’ve come to love and associate with weed.  

THCa is essential to achieving the quintessential cannabis high. We predict THCa will continue to steadily rise in popularity as the future of cannabis continues to progress.

Frequently Asked Questions

What Does THCa Mean?

THCa stands for Tetrahydrocannabinolic acid. It’s the acidic form of Tetrahydrocannabinol (THC) hence the similar names. THCa is simply the acidic form of THC. THCa is a non-intoxicating cannabinoid that can be converted to THC. Once exposed to heat, THCa becomes psychotropic THC

What’s The Legal Status of THCa?

THCa is technically legal, but would be very minute to harvest from a legal hemp crop. The FDA (Food and Drug Administration) categorizes cannabis as a Schedule 1 substance. However, THCa excluded from this distinction.  

The 2018 Farm Bill categorizes hemp as legal if it contains less than 0.3% of Delta 9 THC on a dry weight basis. But THCa is not included in the bill’s definition of hemp. So its legality remains a gray area.

Current loopholes in the 2018 Farm Bill make THCa legal since it’s not considered a federally controlled substance. 

The real understanding lies in the scientific basis that that legal hemp is a Type 3 chemovar, meaning it is naturally CBD-dominant. This means that the plant will naturally make very small to negligible amounts of THCA as opposed to large quantities of CBDA. Type 1 chemovars are THCA/THC dominant, and type 2 are 1:1 THC:CBD.

Since THCa is not included in the legislation it is therefore permitted. Even though THCa seems to lie outside of federal laws, the cannabinoid is still illegal in certain states. 

Be sure to check with your local municipality before buying or trying!

Will THCa Appear on a Drug Test?

Probably, if not definitely. Most drug tests look for the metabolite THC-COOH. THCa is often metabolized into that compound in which case it will show up on a routine drug test. 

If you consume decarboxylated THCa it is converted to THC in the body. So whenever you heat or consume THCa it will most likely appear on a drug test. 

For these reasons, it is highly recommended that you avoid any THCa products.