EducationWhat is the difference between THC and CBD?

What is the difference between THC and CBD?

11 min read

Sam North

What is the difference between THC and CBD?


Cannabis, more specifically the cannabis sativa L. genus, has gone through what can only be described as a meteoric rise in understanding and acceptance over the past two decades. Even up until just a few short years ago, it would have been hard to imagine where the plant would be today, in terms of societal standing and medical awareness.

This truly fascinating species was almost completely off-limits for close to the last century. With a heavy-handed propaganda campaign starting before its criminalisation back in the late 1920s, it was first lambasted in the media as nothing more than some type of 'snake oil' with zero medicinal value, and then condemned by governments as a dangerous recreational drug while also being demonised as a menacing gateway to harder narcotics. It is only in recent times that we have seen the tide begin to turn.

But with the truly monumental social and political shift in attitude towards medical cannabis globally, and here in the UK (medical cannabis became a legal reality here in the UK in November 2018), there is now an ever-increasing understanding and acceptance of the therapeutic potential of cannabis.

So, back to the question at hand…

What is the difference between THC and CBD?

From a chemical standpoint, THC and CBD are actually isomers. This means that although they have the same chemical formula, their structure differs. They are both classed as phytocannabinoids, or cannabinoids produced by the cannabis plant, but their differences in structure mean that they interact with our body’s receptors in entirely disparate ways – and this is what results in their unique therapeutic properties.

To really answer the question fully, we are going to have to look a little deeper into how these two cannabis compounds work, and the subtle yet significant differences between them. But before we do, we first have to discuss the way they interact with the body.

How THC and CBD interact with the human body

All cannabinoids interact with the human body via what is referred to as the endocannabinoid system (ECS). The ECS was first identified in the late 1980s, and has since become one of the most intensely researched areas within neuroscience and medicine.

The endocannabinoid system explained

The ECS is a vast, intricate network of receptors (CB1 and CB2) which are found throughout the brain and body. 

These receptors interact with endocannabinoids, which are cannabinoids produced naturally within the body, acting as chemical messengers. In addition to the receptors and endocannabinoids, the ECS also involves metabolic enzymes that play a crucial role in the production and breakdown of endocannabinoids. This complex system regulates various physiological processes, including mood, appetite, pain sensation, and immune function, making it a fascinating and essential area of study in the field of neuroscience and pharmacology.

CB1 receptors are mostly found in the central nervous system, where they are involved in processing pain signals, controlling appetite, and regulating mood. CB1 receptors in the brain are abundant, surpassing many other receptor types. They essentially function as "traffic lights", regulating the levels and activity of other neurotransmitters. This intricate control mechanism allows them to adjust various functions such as appetite, body heat, pain perception, mood, alertness, and even how we grasp reality. Through immediate feedback, they finely tune the activity of these systems, ensuring optimal regulation.

CB2 receptors are mostly found in the peripheral nervous system and immune cells, where they mediate inflammation and regulate immune responses. They are also found in the brain, where they regulate the release of neurotransmitters and hormones, such as dopamine and glutamate, which are involved in learning and memory, as well as regulating mood and emotional states.

Now that we have that all sorted, let’s look at the differences between THC and CBD, and how these differences affect how they interact with the ECS, as well as other receptors in the body.

The differences between THC and CBD

As we mentioned in the intro, THC (tetrahydrocannabinol) and CBD (cannabidiol) have the same chemical formula, but they possess different chemical structures. Both compounds are made up of twenty-one carbon atoms, thirty hydrogen atoms, and two oxygen atoms.

They do share some similarities in shape, but it is their subtle differences that give rise to contrasting therapeutic and wellness effects they offer.

While the field of medical cannabis research is still in its infancy, what is known so far is that THC and CBD have pathways of action within the body. Thanks to the increased access that researchers now have to cannabis, and the legalisation of medical cannabis in many countries, we are beginning to gain a clearer picture of the contrasting effects that these two compounds have on our body.

Understanding THC

THC, known for its psychoactive, intoxicating properties, has a 'moderate binding affinity' with cannabinoid receptor CB1 in the brain and central nervous system, resulting in the euphoric, joyful, sometimes overwhelming sensation of being 'high'. THC has a remarkably similar chemical structure to one of our endocannabinoids, anandamide, which is often referred to as the 'bliss molecule'.

THC also been shown to interact in a weaker fashion with CB2, and also binds to other receptors in the body, such as serotonin and dopamine receptors. This helps to explain the variety of effects that THC can have on humans, and why it is showing great potential in helping reduce and control the symptoms of a range of health concerns.

What are the main therapeutic benefits of THC?

The therapeutic properties of THC are becoming increasingly clear as more research is done into the plant. To date, it has been shown to help in reducing the severity of conditions such as chronic pain, anxiety, glaucoma, and anorexia. It has also been shown to be effective in decreasing the discomfort relating to the muscle spasms and impaired movements that are symptoms of multiple sclerosis, and reducing the nausea and vomiting associated with chemotherapy and radiotherapy.

It can also be administered to mitigate inflammation (via CB2 receptors), which makes it useful for treating a range of conditions from arthritis to autoimmune diseases.

The intoxicating effects that THC does have on the body mean that its application as a medicinal treatment option is heavily regulated, and here in the UK, it can only be accessed through a prescription from a doctor on the General Medical Council specialist register. Any cannabis-based medical product containing more than 0.2% THC, or 1 mg of THC per container, is classed as a controlled drug and is only legally available through prescription in the UK.

Understanding CBD

CBD is the other major cannabinoid produced by the plant, but unlike THC, it does not offer any intoxicating effects whatsoever. The difference in chemical structure means that it does not have a high affinity for CB1 receptors, instead interacting more strongly with CB2 receptors, 5-HT1A serotonin receptors, and the TRPV1 vanilloid receptors.

It has also been show to have an inhibitory effect on the metabolic enzymes, which are responsible for breaking down our own endocannabinoids, resulting in an increase in the levels of endocannabinoids such as anandamide and 2-AG. This leads to the potential for CBD to have a larger impact on our endocannabinoid system, and by extension, the range of functions that is in charge of regulating.

What are the main therapeutic benefits of CBD?

While much of the research into CBD is still in its early stages, it has already been show to have a variety of therapeutic benefits. It has shown great promise as an anti-inflammatory, a neuroprotective, and as an antianxiety agent. It has also been applied in the treatment of seizures, and is showing great promise in the handling of inflammatory skin conditions such as psoriasis and eczema and neurodegenerative diseases such as Parkinson's.

Given the increasing evidence and anecdotal reports, it is clear that CBD could potentially be an effective and natural treatment for a range of health conditions. CBD is now legal for 'over-the-counter' sale here in the UK, meaning that it is now easier than ever to access.

However, as with any type of medical treatment, it’s important to speak to your doctor before you consider trying it. And even more so when considering implementing CBD as a medical or therapeutic addition to your current treatment plan, as the medical cannabis sector is subject to far stricter regulatory processes than those sourced on the consumer market.

Are there any risks and side effects related to THC and CBD?

As with all medical supplements, THC and CBD do come with some risks and side effects that need to be taken into consideration. Patients often assume that as THC and CBD are both cannabinoids, they will have the same impact on the body and come with the same set of side effects and risks, however this is not the case.

THC has been shown to produce a variety of side effects that range from mild to severe, such as dizziness, dry mouth, hunger and/or thirst, fatigue, red eyes, gastrointestinal discomfort, and an increase in anxiety levels. If consumed in high doses or for extended periods of time, it can cause an increase in heart rate, an elevated risk of psychosis, and cognitive impairments.

As THC is mind-altering, there is a risk of patients becoming dependent on it. Your prescribing doctor will always take this into consideration when deciding if THC should be a part of your treatment plan.

CBD also comes with some unwanted side effects, but these tend to be milder than those associated with THC, and typically only occur when taken in high doses. These include nausea, dizziness, diarrhoea, and changes in appetite or weight.

Both cannabinoids have the ability to negatively interact with some pharmaceutical medications. This is due to the fact that both can affect how the body metabolises certain drugs, which could lead to an increase or decrease in their efficacy.

Final thoughts

Medical cannabis is here in the UK, and it is here to stay!

But understanding the true differences between CBD and THC is key in finding the best option for unique health needs.

THC can be extremely beneficial as a therapeutic agent, but it also comes with some risks and side effects that need to be taken into consideration before beginning treatment. CBD, on the other hand, has no intoxicating effects and offers many therapeutic benefits without any significant risk profile.

By consulting with a doctor who has experience in prescribing cannabis-based medical products tailored for your specific health and wellness requirements, you can rest assured that you will receive the best level of care possible.

If you, or a loved one, would like to learn more about the available medical cannabis approaches, Releaf is here to help. We understand the potential that medical cannabis offers in treating a wide range of medical conditions. With our tailored monthly packages, specialist consultations for medical cannabis, and a unique medical cannabis card for protection, you can access the treatment you require without worrying about the stigma. 

It is important to seek medical advice before starting any new treatments. The patient advisors at Releaf are available to provide expert advice and support. Alternatively, click here to book a consultation with one of our specialist doctors.

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Sam North, a seasoned writer with over five years' experience and expertise in medicinal cannabis, brings clarity to complex concepts, focusing on education and informed use.

Our articles are written by experts and reviewed by medical professionals or compliance specialists. Adhering to stringent sourcing guidelines, we reference peer-reviewed studies and scholarly research. View our editorial policy.

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