Written by Stefan K.

Tetrahydrocannabinol and its effects

Tetrahydrocannabinol, otherwise known as THC, is known to many as the intoxicating component of hashish (hemp resin) and marijuana (hemp in its dried herbal form). Fewer people realise, however, that THC can also be used for therapeutic and medical purposes. Which is reason enough to spend some time looking at tetrahydrocannabinol in this article.

What is THC?

THC stands for tetrahydrocannabinol The correct term is actually (-)-Δ9-trans-Tetrahydrocannabinol, but the complexity of this name means that the more usual term, even amongst chemists, is usually tetrahydrocannabinol.

THC naturally occurs in the form of two THC acids in plants of the genus Cannabis (which is in the Cannabaceae family). Heat turns these acids into THC. This process is known as decarboxylation. Since about 2010, heterologous biosynthesis has also made it possible to synthesise THC [1].

This active substance belongs to the group of compounds known as cannabinoids, of which 113 are currently known, and when taken it interacts with the human endocannabinoid system.

Due to its psychoactive effects, tetrahydrocannabinol is subject to strict regulation in the UK and is scheduled as a class B drug. Whilst possession for one’s own use is tolerated (small quantities), the cultivation and trade of products containing THC is not permitted.


The current exception is the rule that industrial hemp must contain no more than 0.2% THC in order to be marketable. This is based on the understanding that consumption in quantities which would result in intoxication is not possible.

Accordingly, other cannabinoid products, such as hemp oil, CBD oil (cannabidiol oil) and CBD capsules, can only contain a maximum of 0.2% THC.

The effects of tetrahydrocannabinol (THC)

Although THC in its pure form has been known since 1964, it must be noted that THC’s mechanism of action has still not been fully investigated. However, there are now of course a number of effects which have been proven.

Desired effects of THC

Patients who suffer from chronic pain value tetrahydrocannabinol for its analgesic effect. This is not least because the side effects are limited in comparison to those of strong painkillers, such as opioids. Among others, patients suffering from chronic pain have the opportunity to obtain medical cannabis on prescription. The hurdles are high, however.

Cannabis-based medication can be prescribed for chronic pain, neuropathic pain, lack of appetite and vomiting.

The positive effect which substances containing THC have on depression, attention deficit hyperactivity disorder (ADHD), anxiety disorders and post-traumatic stress disorder (PTSD) are also being investigated.

Furthermore, it is thought that it has a positive effect on neurological problems (spasticity and motor disorders), skin diseases (especially atopic dermatitis and psoriasis, as well as on excessive sweating (hyperhidrosis)), and glaucoma (an eye disease).

Undesired effects of THC

THC can also have negative effects, if the dose taken is too high. Delayed absorption in the intestine means that the effects of THC when consumed in food cannot be controlled. Those affected feel dizziness, nausea and may experience incessant repetitive patterns of thought. Speech is often also affected, and comprehensible articulation can become impossible. Anxiety and panic attacks are possible, but are fortunately rare.

The difference between CBD and THC

CBD, i.e. cannabidiol, also belongs to the group of compounds known as cannabinoids and acts on the human endocannabinoid system.

The main difference between the mechanisms of action of CBD and THC in the body is that THC primarily binds to the CB1 receptor, whilst CBD binds to both the CB1 receptor and the CB2 receptor.

  • 1. CBD oil is no panacea but it can certainly help!

    Cannabis and CBD surely are no panaceas but for many people it is a natural remedy that can help with more than 65 different medical conditions. CBD is still quite unexplored but many scientists, doctors and pharmacists shed their prejudices and are interested in the health benefits of cannabidiol. Just always remember: CBD CAN be helpful - but it isn't always.

  • 2) CBD addresses the endocannabinoid system

    Pretty much nobody uses CBD without a reason to do so. CBD is a cannabinoid which is a group of substances that can naturally be found in various plants. These cannabinoids address the endocannabinoid system. Every human has such a system. Via various receptors within this system a number of functions in the body can be regulated, renewed or fixed.

  • 3) Breast milk contains CBD

    A study in 2017 has shown that cannabinoids are not only natural components of cannabis but can also be found in breast milk. Cannabinoids are not only valuable for the neurological growth phases but have many other astonishing health benefits. Without cannabinoids in breast milk newborns would would be less hungry and therefore drink less.

  • 4) CBD is the allrounder amongst cannabinoids

    Every cannabinoid has its own effects. Nonetheless, CBD can be called the allrounder among all cannabinoids. It is not only anti-inflammatory but can also slow down growth of diseased cells. It is also anxiolytic and an immunosuppressant. Therefore, CBD makes for a great dietary supplement and should always be the base. You can add more cannabinoids by choosing full-spectrum CBD products.

  • 5) CBD does not get you stoned

    Cannabidiol is the so-called antagonist of THC. THC means Tetrahydrocannabinol. It is psychoactive and can be found in certain cannabis strains. CBD counteracts with the part of THC that gets consumers 'stoned'. Therefore, the very small amount of THC that can be found in many CBD products is kind of neutralized by the CBD. As a result, CBD products are totally legal and non-psychoactive.

  • 6) WHO rates CBD as harmless

    The World Health Organization WHO published a 27 pages long report where they classify CBD as harmless. The organization states that pure CBD and products that contain less than 0.2% THC are in no way taken into the drug conventions. A reason for that is that CBD is not predicating and there is no danger of abuse. Therefore, CBD is as harmless as water.

  • 7) CBD is not a doping substance and is used in professional sports

    CBD can help reduce inflammations and can support regeneration after physical activities. As a result, many professional athletes (especially in the US) in football, basketball or martial arts use CBD. Many famous athletes also advertise respective compounds. In August 2019 UFC champion Nate Diaz caused a lot of furore when he smoked a CBD joint before a big fight. Nonetheless, it was totally legal since CBD is specifically excluded from the WADA doping list.

  • 8) CBD can be prescribed

    In conventional medicine cannabidiol is not very popular yet. First, doctors need to be informed about CBD in order to shed their prejudices and gather experiences. Nonetheless, even nowadays there are numerous specialists and general practitioners who have trust in the medical potential of cannabis. In some cases doctors also prescribe CBD to their patients.

  • 9) CBD and cannabis can help to cleanse the environment

    Cannabis is a plant that can naturally grow almost everywhere in the world. Additionally, it consumes up to four times as much CO2 as trees. Cannabis is also known for absorbing toxic substances and radioactive chemicals from the soil. Therefore, cannabis is able to cleanse the environment und is good for the earth's climate.
  • 10) CBD exists in all kinds of shapes

    Most people know CBD in the shape of CBD oil. CBD oil is so popular because it is easy to dispense and is well absorbed by the body. Nonetheless, there are numerous other kinds of CBD products such as e-liquids, salves, creams, pastes, flowers, sweets, food or crystals. On you can find many of these products!

Whilst THC is intoxicating / psychoactive, this is not the case for CBD. On the contrary: CBD can counteract the intoxicating effects of THC, having the effect of modulating tetrahydrocannabinol. CBD is therefore often referred to as the antagonist of THC.

At the right dose, THC primarily has relaxing and pain-relieving effects. The pain-relieving properties of CBD are similar, but CBD also helps against anxiety.

Buying tetrahydrocannabinol – what kinds of THC products are there?

With the exception of medical prescriptions, tetrahydrocannabinol is not legally available in the UK at the kinds of concentrations which have a demonstrable analgesic or intoxicating effect. 

In hemp oils, CBD oils and similar preparations, THC is permitted at concentrations of up to 0.2%, so this is the maximum concentration of this active substance that is available. Tetrahydrocannabinol may work better in combination with the other cannabinoids [2].

Tips on using THC the right way

THC is only legal in the UK on prescription. Obtaining the substance by other means constitutes a violation of UK law. THC is generally available in the form of medical cannabis (cannabis flowers and cannabis extracts), as well as in the form of hashish and marijuana.

While medical products containing THC are available as oral sprays, and in the form of pills and drops (oil), hashish and marijuana are inhaled (using a variety of methods, e.g. in a joint or pipe or via a vaporiser) or taken orally (swallowed). For oral consumption, the product is often incorporated into food. As already described in the section entitled “The effects of tetrahydrocannabinol”, special attention needs to be paid to taking the right dose when it is taken orally.


  • THC is the most well-known cannabinoid. Due to its psychoactive (intoxicating) effects, THC is illegal, generally speaking. In the UK, products containing cannabinoids are only permitted to contain THC concentrations up to 0.2% THC.



Taking products containing cannabinoids may result in interactions with various medications. If you are already taking medication, the use of CBD and other cannabinoids should be discussed with your doctor beforehand.

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About the author

Stefan K.

Stefan K.

Stefan is not only a valuable part of the CannaTrust magazine but also convinces with his sound knowledge about the effects of cannabinoids. As an author in Austria he gathered valuable experiences when writing for 'Stadtblatt Salzburg'. He got in contact with cannabis through several positive media reports. Nowadays he writes about everything around the most popular cannabinoid these days: CBD.