What is THCA, and what does it have to do with THC?

25. 07. 2026

What is THCA
THC vs. THCA: Weaker THC? Not quite
What studies say about THCA
What about THCA’s psychoactivity? Is THCA legal?
THCA flower: How it differs from conventional cannabis
THCA: the cannabinoid from which THC is formed
FAQ

What is THCA

THCA stands for tetrahydrocannabinolic acid, more specifically Δ9-THCA-A. It is a precursor to THC, meaning its acidic form, which occurs naturally in cannabis.

It is formed from CBGA, cannabigerolic acid, which is referred to as the mother cannabinoid from which the acidic forms of other cannabinoids are produced – for example, CBDA (the precursor to CBD) or CBCA (the precursor to CBC).

Cannabis plant and a diagram showing how cannabinoids are formed: CBGA → THCA → THC.

THC vs. THCA: Weaker THC? Not quite

As already mentioned, THCA is a precursor to THC, but they are not the same substance. They differ in their chemical structure and in how they behave in the body.

Tetrahydrocannabinolic acid is sometimes described as an inactive form of THC. However, it is more accurate to describe it as a non-intoxicating precursor to THC that does not produce the psychoactive effect typically associated with cannabis when it has not been heated.

The chemical structure of THCA, specifically the presence of a carboxyl group, limits its ability to bind to receptors in the body’s endocannabinoid system.

Psychoactive THC is formed from THCA through a process known as decarboxylation, in which exposure to heat and time removes the carboxyl group from THCA.

The resulting effect of a product containing THCA therefore depends greatly on whether the THCA is heated during processing or use and converted into THC. While consuming fresh, unheated cannabis leaves containing THCA will not produce an intoxicating effect, heating them, for example by smoking or vaporisation, converts some of the THCA into THC, which has a psychoactive effect.

	THCA	THC
Name	tetrahydrocannabinolic acid	tetrahydrocannabinol
Relationship between the substances	precursor to THC	formed from THCA
Difference in chemical structure	contains a carboxyl group	does not contain a carboxyl group
Form	acidic	neutral
Psychoactivity	no	yes

What studies say about THCA

There are currently significantly fewer studies examining THCA than studies focusing on THC or CBD, and they have not yet produced any definitive conclusions.

A study published in the British Journal of Pharmacology in 2013 focused on the relationship between THCA, nausea and vomiting. The authors examined THCA in preclinical models, specifically in rats and musk shrews. In the rat model of acute nausea, THCA reduced conditioned gaping induced by lithium chloride, while in musk shrews it reduced vomiting.

Another study published in the same journal in 2017 investigated whether THCA can activate the PPARγ receptor, a cellular receptor involved in regulating inflammatory processes, certain protective cellular mechanisms and fat metabolism, among other functions. Tests conducted using cell models and mice showed that THCA affected some of the monitored parameters associated with anti-inflammatory and neuroprotective activity.

A study published in 2023 examined CBDA and THCA in relation to Alzheimer’s disease. The authors reported that CBDA and THCA may cross the blood–brain barrier, meaning that they may pass from the blood into brain tissue, and affected some of the monitored parameters in the in vitro and in vivo models used.

Although this does not constitute direct evidence that THCA can treat Alzheimer’s disease or other neurodegenerative diseases, the study’s findings suggest a potential benefit that warrants further research.

A microscope examining THCA crystals, with icons relating to areas of preclinical research: neuroprotection and nausea.

Is THCA psychoactive? Is it legal?

Simply put: unheated THCA is not psychoactive, but when heated, some of the THCA is converted into THC, which has intoxicating effects.

Because THCA can be converted into THC through heating, legislation often takes into account not only the THC content of cannabis products, but also the THCA content converted into its THC equivalent.

For example, European Commission Regulation 2022/1393 explicitly states that Δ9-THCA may be converted into Δ9-THC during processing. The maximum levels for hemp seeds and products derived from them are therefore established as the sum of Δ9-THC and converted Δ9-THCA, expressed as “total THC potential”.

When Δ9-THC and Δ9-THCA are determined separately, THC potential is calculated using the following formula: Δ9-THC + 0.877 × Δ9-THCA.

The coefficient 0.877 is based on the difference in molecular weight between THCA and THC. During decarboxylation, the carboxyl group is removed from THCA, meaning that the resulting THC molecule has a lower weight than the original THCA molecule.

As far as legality is concerned, in practice it always depends on the analysis, the laws of the country in question, how the product is marketed and the legal regime applicable to the relevant category. Different rules may apply to industrial and medical cannabis, food, cosmetics, smoking products, extracts and collectors’ products.

THCA flower: How it differs from conventional cannabis

THCA flower is cannabis flower with a higher tetrahydrocannabinolic acid content ranging from several percent to tens of percent. At first glance, it is virtually indistinguishable from other cannabis flower, but the difference lies in its laboratory profile.

THCA occurs naturally in cannabis. It is produced in the trichomes, the plant’s resin glands. In fresh flower, most of the potential THC is therefore present in the form of THCA, while THC itself appears in larger quantities only after decarboxylation.

The amount of THCA contained in cannabis depends mainly on the strain, the plant’s maturity, cultivation method, drying, storage and other factors.

Industrial hemp generally has a low THCA content because the plant is bred to have a low total THC potential. By contrast, strains cultivated for a high THC content have a higher THCA content.

THCA flower can be produced in two ways. The first possibility is that it consists of naturally grown cannabis flower from strains with a high THCA content. The second possibility is that conventional cannabis flower is subsequently enriched with an extract.

THCA flower may have a naturally high THCA content or be enriched with THCA extract.

In addition to flower, other products are also available on the market, ranging from THCA isolates to THCA edibles. The availability of these products depends on their THCA concentration and the legislation of the country in question.

THCA: the cannabinoid from which THC is formed

THCA is the acidic precursor to THC and occurs naturally in fresh cannabis. In the plant, it is formed from CBGA and is converted into THC through decarboxylation.

The main difference between THCA and THC is the presence of a carboxyl group in THCA, which causes it to behave differently in the body. .

The effects of THCA are not fully understood, as sufficient scientific data are not yet available. The substance is being investigated in relation to nausea, inflammation and neuroprotection.

The legal status of THCA varies from country to country. New regulations generally focus not only on the amount of THC, but also take the THCA content into account because it can be converted into THC during decarboxylation. The so-called total THC potential is therefore important for products and is determined by converting THCA into its THC equivalent on a molecular basis.

FAQ

1. Can the THCA content be determined from the appearance of the flower?

The THCA concentration in cannabis flower can be determined reliably only through laboratory analysis, not by its appearance.

2. Can the concentration of THCA in a product change over time?

Yes, THCA can be converted into THC over time, particularly under unsuitable storage conditions. It is therefore important to follow the manufacturer’s instructions and check the expiry date of THCA products.

3. What is the difference between flower with a naturally high THCA content and flower enriched with an extract?

In flower grown for a high THCA content, the concentration is determined not only by the plant’s genetics, but also by its growing conditions. As a result, each harvest may not be exactly the same, and the concentration may be affected by changes in temperature or soil conditions. It is common for the THCA content to vary slightly between batches.

Flower enriched with THCA extract is produced by applying a concentrated extract to plant material. As a result, it generally contains a higher amount of THCA.

4. Can THCA show up on a drug test?

Drug tests do not detect THCA, but THC metabolites, particularly THC-COOH. The risk of a positive result depends on the amount of THCA in the product, the method and frequency of use, the individual’s metabolism and the sensitivity of the test.

Given the chemical similarity of the two substances and the ease with which THCA can be converted into THC, there is a possibility of a positive drug test.

Sources:

Author: Natálie Kubíčková

Photo: AI

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