Under the Microscope

The Essence of THCa in Cannabis

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13/03/2023 The Scoop on THCa

THCa is buzzing in the cannabis community. Why? What is THCa and why does it matter to know the difference between THC and THCa? 

Go grab the packaging from some marijuana flower or a pre-roll and let's examine a few of the lab test results on a label and what those numbers mean. Have a calculator handy as well.


What is THCa?

THCa or tetrahydrocannabinol acid (yes, it's a mouthful) is the acidic form of THC. Ok, what's that mean? Well, the long and the short of it is, THC is what THCa becomes when heat is applied to cannabis, such as when you smoke, dab, or vape. When you want to know how high something will get you or the benefits you can reap, consider these two measurements to be the key.

THCa is a non-psychoactive cannabinoid, one of the hundreds of compounds found in the raw cannabis plant. When THCa is heated up to the right temperature, THCa changes to psychoactive THC. The secret is in the heat (decarboxylation or decarbing). So if you smoke flower, vape, dab, and cook with cannabis the higher the percentage of THCa the more THC the product will end up with after heat is applied. THCa on its own won't get you high, it needs heat.


What are Those Numbers on Cannabis Labels?

So hopefully you can grab a container of cannabis flowers to look at the label. There are many different components to laboratory testing of cannabis. There are no federal regulatory labeling laws across the board, however, the cannabis/hemp industry is striving for some normalized standards. 

On the label, there are compounds usually listed in percentages such as THC, THCa, CBD, CBN, CBG, and perhaps the individual terpenes listed, as well. For our peek into cannabis today we want to focus on the two percentages of THC and THCa levels, so make note of what they are. We will come back to the numbers later.

The way to figure out how much THC you have after decarbing the cannabis is in a chemistry formula. Yikes! Don't worry, it isn't that hard to figure out. Calculator time! 

Take the THCa percentage listed (% of weight) x .877 + ∆9THC (% of weight). Sounds daunting, I know. Let's see if it can be made clearer than mud.

The THCa percentage listed is the amount of THCa (non-mind-altering) before decarboxylation. The .877 is the weight that is lost during the heating process (shrinkage). The THC percentage is the amount of naturally occurring THC before heating. 

Now plug all those numbers in the right spot and what you have left is the amount of THC in the cannabis product as you are smoking or vaping. The percentage reflects the "activated" THC level in the product. This is the final number to pay close attention to. 


So you can see in this example that if the THCa is 18.842% and the THC is .377% then according to the formula:

Thca (18.842%) x .877 + THC (.377%) = Total THC (16.6%) or 

18.842% x .877 + .377% =16.6%

The percentage of total THC is 16.6%.

As you can see in this example, the stated percentage of THC on the label is only a fraction of what you end up with after you light up a joint or dab some THCa crystals. Usually, cannabis with a final THC percentage over 15% is considered to be potent.


What is Decarboxylation?

Decarboxylation is the act of heating raw cannabis and releasing carbon dioxide from it. Once the cannabis is heated, the weight is reduced because carbon dioxide is released as it converts to THC. Now you have a greater amount of THC than you started with in the raw product. It is now, very psychoactive. THCa alone before decarbing does not seem to bind to the CB1 receptors like THC. 

Each component of cannabis can affect each person consuming it differently. The compounds within cannabis/hemp are many and vary from strain to strain. The combined effects (entourage effect) of all of these compounds within your system can be even stronger. It is important to have an understanding of the possible effects of THCa alone and after it is converted to THC.

But Is it Legal? In Hemp?

Yes, THCa is legal federally. However keep in mind that when THCa is converted to THC, at that point it becomes a mind-altering, Schedule1, illegal substance at the federal level. Possibly, depending on your location, it could be illegal in your state as well. Please check your state and local laws.

Much is needed to be done, from a regulatory standpoint, to bring all laws federal, state, and local in sync with one another. Until then many components of cannabis/hemp will exist in a gray area.

This is how hemp can legally have less than .3% of THC (per federal Hemp laws) in the raw product but can end up having a greater amount of THC after smoking than is allowed by federal law. It could take a theoretically, non-psychoactive product into the realm of mind-altering and possibly an illegal substance.

THCa in Cannabis

What can THCa Do for Me?

THCa in its raw form has indications that it can help with inflammation. So people with diseases and conditions such as Crohn's, arthritis, Lupus, and other inflammatory diseases may benefit from ingesting raw THCa. (salad, smoothies)

THCa has neuroprotective properties as well. Diseases such as Alzheimer's, Dementia, brain tumors, and Parkinson's disease may see beneficial treatment with THCa. 

Early indications suggest that some cancer cell growth may be inhibited by THCa. Nausea can be relieved as well and might be helpful during cancer treatments and the treatment of diseases such as anorexia nervosa.

The study of cannabis is still in the early stages in the United States. As cannabis becomes more mainstream, and independent studies are published by US companies, we will continue to learn more about the benefits of each piece of this wonderful plant. 


CB1 and CB2 

THCa properties 

Hemp Act 2018