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THCA (Tetrahydrocannabinolic acid)


THCA (Tetrahydrocannabinol-acid) naturally occurs in cannabis plants, and it's the precursor of THC (Tetrahydrocannabidiol). THCA is slightly different from THC, as it contains an extra acid group. This acid group detaches when cannabis is heated.

When you smoke weed, all THCA is converted into THC. The extra acid group in THCA also automatically detaches over time. This is why old weed contains much more THC than fresh weed. Unlike THC, THCA has no psychoactive effect. However, research has shown that THCA can treat certain physical problems. 

This is why THCA oil, alongside CBD oil, is vastly increasing in popularity. THC, THCA and CBD are all cannabinoids. These are specific substances that only occur in cannabis plants. In this article, we will take a further look at the biochemical aspects of THCA. We will also explain how to make your own THCA oil, which requires a very different process from making THC or CBD oil. Due to THCA converting into THC when heated, this extraction method should be performed at room temperature. We will also discuss how to test if the oil you made is indeed THCA oil.

The history of cannabis oil

Over two and a half thousand years before Christ, Chinese emperor Shen Nung discovered the healing effect of cannabis. This emperor was also known as the father of Chinese medicine. He advised taking cannabis for treating constipation, rheumatism, and pain. The Greek used the cannabis plant to improve bowel movement. The Romans used it for earaches and menstrual cramps. 

Do keep in mind that the cannabis they used thousands of years ago, is in no way comparable to the super strong "Nederwiet" you find in Dutch coffeeshops. This weed generally contains mainly THC, and hardly any CBD. Would you like to know more about CBD? Read our encyclopaedia article on CBD here. This article explains how the demand for stronger weed resulted in a disbalance between cannabinoids found in Nederwiet.

It was Irish doctor William Brook O’Shaughnessy who first introduced weed as a medicine in the ninetieth century in West Europe. In 1833, he moved to India to work as a doctor. He became aware of the customs of the indigenous people of the country and found out about the healing effects of cannabis. O’Shaughnessy made tinctures of the cannabis plant’s flowers, making the first weed oil in history. The Irish doctor used the oil to treat rheumatic pain, migraine and muscle spasms. This made cannabis increase in popularity in Europe. Even the Royals were into it. Queen Victoria, for example, used weed to relieve her menstrual pain. Around 1840, stronger painkillers entered the market, including aspirin and morphine, making cannabis oil as a painkiller obsolete.

In 1937, as a result of the war on drugs, any use of cannabis was made illegal. Using a lot of propaganda, cannabis was demonised, followed by a worldwide ban on weed. Cultivating industrial hemp was, still allowed, albeit under strict surveillance. However, consuming cannabis, even for strictly medical purposes, was prohibited. Unfortunately, this ban made is practically impossible to do any research on the medicinal effects of cannabis.

In 1964, THC was first isolated. This discovery was the start of several research trials on the biochemistry of the many different cannabinoids. However, this was very difficult to do; due to cannabis being illegal, funding was hardly available.

Fortunately, a revised version of the opium law was implemented in 1976. This led to decriminalisation of weed. Then, in 1996, medicinal cannabis was legalized in California. In Washington, recreational use was legalized in 2012. Worldwide decriminalisation of cannabis makes it possible for proper research to be performed on cannabinoids and their possible medical purposes. This also includes research on THCA, which has a completely different effect from its degradation product; THC. In some ways, THCA seems to even be superior to THC.


Due to the fact that THCA easily degrades into THC, both substances have the same legal status. In the Netherlands, you are allowed to own and use THC oil. But selling it in a store or on the internet is illegal. Coffeeshops have an even harder time selling THC oil; they’re legally not allowed to sell more than 5 g of weed per customer, and 25 ml of THC oil (depending on the strength) contains more than 5 g.


The A in THCA stands for acid. This shows how much the chemical structure of THCA resembles THC. The only difference is the extra acid group THCA has. In chemistry, an acid group is called a carboxyl group. THCA is the precursor to THC.

THCA biochemistry

Due to THCA’s extra acid Group, the THCA molecule does not attach to CB1 cannabinoid receptors, like THC does. This is why THCA doesn’t have a psychoactive effect. THCA, however, attaches to the TRPM8 receptor (the one that makes us experience a sensation of cold when we taste mint) and activates the TRPA1 receptor (which makes us feel the spiciness when we eat things like mustard or cinnamon). It is possible that the therapeutic effect of THCA is caused by it blocking MAGL enzymes. This type of enzyme is responsible for breaking down the cannabinoids produced by the body, which bind to CB1- and CB2 receptors. Unfortunately, not a lot of research has been done, making it unclear how exactly THCA works.


Depending on the quality of the THCA oil, it is not psychoactive. Only very sensitive people might notice a slightly calming effect. However, not all THCA oil is produced properly, making the possibility of it containing quite some THC very real. In addition to that, THCA degrades very quickly into THC. At room temperature, THCA is stable for only four days, although at -20 °C it can be stored for two months.

After this time period, THCA oil will contain THC. The longer you wait, the higher the level of THC. THCA oil made of older weed flowers will contain more THC than oil made of fresh flowers. Make sure you’re careful when you open a new bottle, or when you switch to a new supplier. Always start with a very low dosage to test if it contains any THC.

THCA Medicinal use

Now that we learned that THCA oil in some ways works better than THC oil, more and more research is being done on the possible medical effects of the substance. Due to THCA not inducing a high, it’s easier to use as a medicine. What follows is a list of results of scientific research. Do keep in mind that these are not medical claims – in order to make proper claims, much more research needs to be done. When you receive treatment, always consult your doctor before you try THCA oil.  

  • THCA increases appetite. In a society where obesity is considered a massive problem, this might not seem like a positive effect at all. However, if someone who, for example, has cancer, loses a lot of weight and has hardly any appetite, THCA might offer a solution. THCA also relieves feelings of anxiety, gives more energy and effectively prevents vomiting. When it comes to preventing nausea after chemotherapy, THCA is proven to be superior to THC. It’s possible that THC is not even responsible at all for preventing nausea; it might always have been the small amount of THCA still present in the THC oil. THCA oil could work really well for eliminating some of the negative effects of chemotherapy. [1]
  • THCA can diminish certain types of epileptic seizures, and in some cases, it can even make them stop. In this case, a higher doesn’t always make for better results. [2] It also seems that CBD can diminish epilepsy. CBD does not degrade into THC, which might make CBD oil a safer option.
  • THCA possibly has a nerve protecting effect, making it a possible treatment for neurodegenerative conditions like Parkinson. [3][4]
  • It might also have an anti-inflammatory effect; THCA lowers COX1 levels with 50% and COX2 levels with 30%. COX1- and 2 make for the inflammatory response in the body. [3]
  • On top of that, there is more and more scientific proof that certain cannabinoids, including THCA, can reduce certain types of cancer. [5]

Making your own THCA oil

First of all, it’s important to use fresh buds from plants with high THC levels. This, by the way, is not entirely true, as cannabis plants contain only THCA, until right after harvest. When the weed is heated, THCA converts into THC, creating a ‘stoned’ effect. If you’d eat some fresh, raw buds, you wouldn’t notice a psychoactive effect. The longer you wait, the more THCA will convert into THC. This is why you should grow your own plants, and make the THCA oil right after harvesting your buds.

Then, cut or grind the buds and add at least 500 ml medicinal alcohol to 20 g of weed. Leave this in a cool space for one day. Then, filter the buds from the alcohol; you could use a panty for this. Filter the liquid again through a coffee filter. You’re now left with a green, clear, flammable liquid.

Now, make the alcohol evaporate, keeping the temperature under 40 degrees, to minimalise conversion into THC. You can make the alcohol evaporate using a temperature controlled water bath. A dehydrator, often used in the raw food movement, is another option. You could also put the extract on a flat bowl, and put it under a fan. If you do this, watch out, because alcohol fumes are very flammable. It’s very important to make sure the room is well ventilated. When the alcohol has evaporated, you’re left with a thick, hash-like substance. You can dilute this with olive oil.  

Testing your THCA oil

If you feel stoned after taking THCA oil, there is no doubt that it contains THC. By trying it out, you can easily test if it contains THC. If you want to work in a more serious way and find out what the exact levels are, you could consider getting your oil tested at a special laboratory. Now that making weed oil is increasing in popularity, more and more test labs will test your oil for you. 

Of course, you have to choose a lab where they can test your sample the same day. Another option is to ask them to store the oil at -20 °C. Also make sure you know what equipment they use; gas chromatography is not suitable to test THCA levels, as it uses high temperatures, making all the THCA convert into THC. An HPLC analysis, however, is done at room temperature, making it a very suitable method for testing your cannabis oil. 


Het mag duidelijk zijn dat THCA een heel andere uitwerking heeft dan THC. Omdat THCA echter zeer snel tot THC degradeert, is voorzichtigheid geboden. Wanneer stoned worden zeer onwenselijk is, bijvoorbeeld omdat een kind de olie gebruikt, is het mogelijk verstandiger om CBD-olie te gebruiken. CBD heeft namelijk veel eigenschappen die overeenkomen met THCA. Toch is THCA een heel interessante stof die kan worden ingezet als uitgangsstof binnen farmaceutisch-onderzoek. Vanuit THCA kunnen waarschijnlijk medicijnen worden vervaardigd die veel op THCA lijken, maar wel stabiel zijn.

It's obvious that THCA works differently from THC. THCA easily degrades into THC, so caution is advised. When getting stoned is absolutely not desired, for example, when a child uses the oil, using CBD oil might be a safer option, as CBD has many similarities to THCA. Still, THCA is a very interesting substance that  


1. Tetrahydrocannabinolic acid reduces nausea-induced conditioned gaping in rats and vomiting in Suncus murinus, http://onlinelibrary.wiley.com/doi/10.1111/bph.12316/full

2. Medical Marijuana for Seizures, https://www.projectcbd.org/medical-marijuana-seizures- sulak-saneto-goldstein

3. Non-psychotropic plant cannabinoids: new therapeutic opportunities from an ancient herb, http://www.sciencedirect.com/science/article/pii/S016561470900128

4. Tetrahydrocannabinolic acid is a potent PPARγ agonist with neuroprotective activity. https://www.ncbi.nlm.nih.gov/pubmed/28853159

5. Non-THC cannabinoids inhibit prostate carcinoma growth in vitro and in vivo: pro-apoptotic effects and underlying mechanisms. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3570006/

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