Getting the Facts Straight: THCa vs. THC

These days, it seems that almost every few months there’s a new marijuana referendum up for vote or a new cannabis bill in committee or awaiting a state governor’s signature. Fully legal in 10 U.S. states including Washington D.C., and medicinally legal in over 20 additional states, marijuana legalization is gaining ground across the nation, leading many to believe that we are on the cusp of full U.S. legalization within the next five to 10 years.

As social and legal barriers to marijuana use and education continue to fall and both medical and recreational marijuana markets continue to mature, our understanding of the complex cannabis plant is growing by leaps and bounds. But we still have much more to learn about the plant's unique makeup. A good first step, laboratory testing is increasingly becoming a requirement for marijuana or marijuana-infused product manufacturers, and many products sold today come with labels defining their contents.

But as marijuana use in the U.S. continues to rise, more and more users are starting to ask questions about the complicated makeup of marijuana and how it interacts with our bodies and minds. And if you’ve ever been confused by all the acronyms — THCa vs THC vs CBD and more — just keep reading.

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Marijuana’s Cannabinoids

Did you know that cannabis is made up of at least 113 different cannabinoids, many of which are still being studied by scientists? Legalization should make it easier to dive deeper in the coming years as the market and science behind it all continues to mature, but there’s a lot we do know about cannabis and its makeup.

Most people know about marijuana’s main psychoactive ingredient, THC, and awareness is slowly rising around CBD, another well-known cannabinoid, but many don’t know that THC (as well as CBD) actually has a related cannabinoid known as THCa (the CBD version is similarly called CBDa).

What is THCa?

Simply put, THCa is kind of like THC before the plant dries out. It’s a precursor to THC before the chemical reaction that releases carbon dioxide takes place, converting the existing THCa to THC. In a sense, it’s the raw form of THC, and is THC before THC exists. In a marijuana plant, THCa converts itself during the drying process to THC. This happens as buds are “cured,” and also during combustion or heating such as while smoked, vaped, or cooked.

However, even as the march of time will convert THCa to THC due to the unstable nature of THCa, traces of THCa can be found in dried buds and even in users that have smoked marijuana by combustion or another heating method. Over time, the THC itself further breaks down into cannabinol, or CBN, which is most commonly associated with aged cannabis, and has a much milder psychoactive effect than THC.

Unlike with dried flower or edibles, THCa is often the primary marijuana extract found in resins such as hashish and other oils, sometimes exceeding 90 percent of the product’s weight. Note that when burnt, the THCa is converted to THC, which produces the psychoactive effect common to marijuana usage.

What Is the Difference Between THCa and THC?

thc molecule drawing

The main difference between THC and THCa is that while THC is most directly linked to the “high” users experience after smoking or otherwise heating dried marijuana for consumption, THC is actually the result of a chemical reaction that takes place within marijuana during the drying (or combustion) process, which sees THCa turn into THC. But what is the difference? And should you care?

Expressing the differences between the two cannabis plant compounds can be done by examining the two cannabinoids at the molecular level. THCa, shorthand for delta-9 tetrahydrocannabinol acid, is the carboxylic acid form of THC, also known as delta-9 tetrahydrocannabinol.

What Is a THCa to THC Conversion?

Under normal circumstances, the carbon in THCa prevents the psychoactive THC from showing itself. Unlike THC, THCa — much like both CBDa and CBD — produces no psychoactive "high" or related euphoria. The process of removing the carbon and oxygen molecules, known as decarboxylation, is done simply by adding heat, either through a drying or curing process or through combustion or vaping. Believe it or not, it’s why eating raw marijuana will not get you stoned, but smoking, cooking or otherwise heating it will.

It is also important to note that laboratory labels on medical or recreational cannabis usually list both THCa and THC concentrations, which many add together to gauge the full potency of the product. So, if the THCa vs THC ratio tests at 18% THCa and 1.5% THC, the product, once activated by heat, common sense tells us, will contain 19.5% THC. However, this is inaccurate. THCa percentages must be multiplied by the molecular mass of THC before it can be translated into the final THC potential. To do this at home, you can try the following equation to get a better idea:

THC total = (%THCa) x 0.877 + (%THC)

The long and short of it is that the THCa vs THC debate is actually the comparison of two different but complementary roles in the efficacy of the cannabis plant. When it comes to users, THC is what gets you high, but THCa is the plant’s potential to get you high once combusted. They’re sort of the same, but not at all, and the only thing you need to remember is that when you light up, THCa becomes THC. And while some debate the beneficial effects of THCa sans combustion, it won’t give you the giggles or have you staring endlessly at the wall.

If you’d like to learn more about THCa, check out our blog for the most potent cannabinoid of them all: THCa crystalline. Cannabis diamonds are another type of super-concentrate if you’re looking to move on from flower or edibles.