Cannabinoids Explained: THC, CBD, CBG, CBN & More | PatientsCann UK

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Understanding Cannabinoids

Cannabinoids are the active compounds in cannabis. They are the reason a cannabis medicine can ease pain, calm the mind, or help with sleep. This guide explains what they are, how they work in your body, and why heating the plant changes everything.

13 cannabinoids Interactive receptor map Accurate chemical structures Plus THC metabolism

What are cannabinoids?

Cannabinoids are a family of natural compounds made by the cannabis plant. Scientists have found more than 100 of them. They are the part of the plant that makes it useful as a medicine.

Each cannabinoid has its own job. THC eases pain and sickness but also causes the "high". CBD is calming and does not make you high. Others, like CBG and CBN, are being studied for focus, sleep and much more.

Your body already makes its own cannabinoid-like chemicals. Plant cannabinoids work by borrowing the same network in your body. Scientists call it the endocannabinoid system, or ECS for short.

Cannabinoids rarely work alone

Alongside the aroma compounds called terpenes, cannabinoids seem to work better together than apart. Scientists call this the "entourage effect". It is one reason a whole-plant medicine can feel different from a single pure cannabinoid. Learn more on our terpenes guide.

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How Cannabinoids Work in the Body

Your endocannabinoid system has two main "locks", called receptors: CB1 and CB2. Cannabinoids are the "keys". CB1 sits mostly in the brain and nerves. CB2 sits mostly in the immune system and around the body. Pick a cannabinoid below to see which locks it fits, and what that might mean for you.

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Raw vs Heated: Why Cannabis Must Be Warmed

Here is something that surprises most people: raw cannabis will not get you high. The plant does not make THC or CBD directly. It makes their acid forms first, called THCA and CBDA. Only when you add heat, by vaping, smoking or cooking, do these acids lose a tiny piece (a carbon dioxide molecule) and turn into THC and CBD. This is called decarboxylation. Follow the pathway, tap any molecule to see its structure, then press Apply heat.

The plant makes acids (left). Heat turns them into the cannabinoids you know (right).

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In Your Body: What Happens to THC

Heating the plant makes THC, but the story does not end there. Once THC is inside you, your liver changes it step by step into new molecules. One of them is stronger than THC itself. This is the hidden reason an eaten edible can feel so different from a vape, and why the same dose can affect two people in completely different ways.

The key player

11-Hydroxy-THC is a metabolite: a new molecule your body makes while breaking THC down. It is not in the plant. It fits the CB1 receptor even better than THC, so it is stronger and reaches the brain more easily.

Does the route change things? Try it

Inhaled: mostly THC reaches your brainRough share of active cannabinoid in your blood
THC11-OH
Delta-9-THC11-Hydroxy-THC (stronger)

Fast and lighter. Inhaled THC goes almost straight to your brain, mostly unchanged. Very little becomes 11-hydroxy-THC. Onset is quick (minutes) and the effect fades sooner.

The breakdown pathway

Full profiles:11-Hydroxy-THC THC-COOH

Why edibles feel stronger

When you eat cannabis, most of the THC is turned into 11-hydroxy-THC before it reaches your bloodstream. A gentle vape and an intense edible can come from the very same flower. (Huestis, 2007)

Why they fail for some

Everyone's liver runs at a different speed. The main enzyme, CYP2C9, comes in different genetic versions, so blood levels from the same dose vary widely between people. (Sachse-Seeboth et al., 2009)

A fast liver can rush THC through to the inactive THC-COOH and clear it before much is felt, so a normal edible seems to do nothing.

Where nano-emulsions help

Nano-emulsified edibles wrap THC in tiny food-safe droplets, so more is absorbed, faster, and some slips past the liver's first pass. They do not make THC more powerful; they make the dose more reliable. (Hermush et al., 2025)

Patients first: because bodies differ so much, never chase an edible with a second dose too soon; give it up to two hours. Ask your prescriber which format and strength suit you best.

At a glance

THC vs CBD: The Two You Hear About Most

THC and CBD come from the same plant and look almost identical under a microscope, yet they behave very differently in the body. Here is the simple version.

THC

Delta-9-tetrahydrocannabinol

Makes you high?
Yes. It switches on CB1 in the brain.
Mainly used for
Pain, muscle spasm, nausea, appetite and sleep.
How it works
Directly activates the CB1 and CB2 receptors.
UK status
Prescription only, from a specialist doctor.
Watch for
Anxiety, a racing heart or dizziness at higher doses.

CBD

Cannabidiol

Makes you high?
No. It barely touches CB1.
Mainly used for
Anxiety, epilepsy, inflammation and calm.
How it works
Acts mostly on other targets, and softens THC.
UK status
Low-THC CBD sold as a supplement; medical CBD is prescribed.
Watch for
Usually well tolerated; can interact with some medicines.

Full library

The Cannabinoid Family

Select any card to open the full profile, with its accurate chemical structure, how it works, what the research says, and safety notes. Use the filters to narrow the list.

    Questions

    Cannabinoids: Your Questions Answered

    What is the difference between THC and CBD?
    THC is intoxicating: it switches on the CB1 receptor in the brain, which causes the "high" and also eases pain and nausea. CBD is non-intoxicating: it barely touches CB1 and works mostly on other targets, and is studied for anxiety, epilepsy and inflammation. Many patients use a medicine that contains both.
    Which cannabinoid gets you high?
    Delta-9-THC is the one responsible for the "high". Delta-8-THC and CBN are only mildly intoxicating. CBD, CBG, CBC, THCV, CBDV and the raw acids (THCA, CBDA, CBGA) do not make you high.
    Do I need a prescription for cannabinoids in the UK?
    Cannabis medicines that contain THC can only be prescribed by a specialist doctor on the General Medical Council's Specialist Register. Some low-THC CBD products are sold in shops as food supplements, but a medical cannabis prescription is a different thing. Our Start Your Journey guide explains how to access one.
    What is the endocannabinoid system?
    It is a network of receptors, natural chemicals and enzymes found all over the body. Its two main receptors are CB1, mostly in the brain and nerves, and CB2, mostly in the immune system. It helps to keep things like mood, sleep, appetite and pain in balance. Plant cannabinoids work by acting on this same system.
    Why does cannabis need to be heated?
    Raw cannabis contains acid forms such as THCA and CBDA, which are not intoxicating. Heating them (by vaping, smoking or cooking) removes a carbon dioxide molecule and turns them into THC and CBD. This is called decarboxylation. It is why eating raw flower will not have the same effect as a heated product.
    Are cannabinoids addictive?
    THC can lead to dependence in some people, especially with heavy, long-term use. Non-intoxicating cannabinoids like CBD are not thought to be addictive. Your prescriber will help you use your medicine safely. Never change your dose without speaking to them first.
    What is the entourage effect?
    It is the idea that cannabinoids and terpenes work better as a team than on their own. For example, CBD and certain terpenes may shape and soften the effects of THC. It is still being researched, but it helps explain why whole-plant medicines can feel different from single pure compounds.
    Why don't edibles work for some people?
    Eaten cannabis is changed by your liver before it reaches the rest of your body. Everyone's liver works at a slightly different speed, mostly because of a gene called CYP2C9. Some people turn THC into its active form and then quickly into the inactive THC-COOH, clearing it before they feel much. Others build up a lot of the strong metabolite 11-hydroxy-THC and feel powerful, long effects. Nano-emulsified edibles are absorbed more fully and reliably, which can help when standard edibles seem to do nothing. Always talk to your prescriber before changing how you take your medicine.
    What is 11-hydroxy-THC?
    11-Hydroxy-THC (11-OH-THC) is a molecule your body makes while breaking down THC in the liver. It is not found in the plant. It is actually stronger than THC and reaches the brain more easily, which is the main reason eaten cannabis can feel more intense and last longer than a vape. Your body then changes it again into the inactive THC-COOH, which is later flushed out.
    Sources: Molecular structures drawn from PubChem canonical data (NCBI, 2025). Receptor and effect summaries simplified from Pertwee (2008), Russo (2011), Izzo et al. (2009) and Morales et al. (2017). Metabolism summarised from Huestis (2007), Sachse-Seeboth et al. (2009) and Hermush et al. (2025). Boiling points and formulas from PubChem. This page simplifies complex science for patients and is not a substitute for advice from your prescriber.

    References

    1. Baram, L. et al. (2022) 'Major cannabis terpenes, applied individually and in combination, activate endogenous cannabinoid CB1 and CB2 receptors', Frontiers in Pharmacology, 13, 1040962. doi: 10.3389/fphar.2022.1040962.
    2. ElSohly, M.A. and Gul, W. (2014) 'Constituents of Cannabis sativa', in Pertwee, R. (ed.) Handbook of Cannabis. Oxford: Oxford University Press, pp. 3-22.
    3. Gaoni, Y. and Mechoulam, R. (1964) 'Isolation, structure, and partial synthesis of an active constituent of hashish', Journal of the American Chemical Society, 86(8), pp. 1646-1647. doi: 10.1021/ja01062a046.
    4. Grotenhermen, F. (2003) 'Pharmacokinetics and pharmacodynamics of cannabinoids', Clinical Pharmacokinetics, 42(4), pp. 327-360. doi: 10.2165/00003088-200342040-00003.
    5. Hermush, V. et al. (2025) 'Enhancing cannabinoid bioavailability: a crossover study comparing a novel self-nanoemulsifying drug delivery system and a commercial oil-based formulation', Journal of Cannabis Research, 7, 31. doi: 10.1186/s42238-025-00294-8.
    6. Huestis, M.A. (2007) 'Human cannabinoid pharmacokinetics', Chemistry & Biodiversity, 4(8), pp. 1770-1804. doi: 10.1002/cbdv.200790152.
    7. Izzo, A.A. et al. (2009) 'Non-psychotropic plant cannabinoids: new therapeutic opportunities from an ancient herb', Trends in Pharmacological Sciences, 30(10), pp. 515-527. doi: 10.1016/j.tips.2009.07.006.
    8. Morales, P., Hurst, D.P. and Reggio, P.H. (2017) 'Molecular targets of the phytocannabinoids: a complex picture', Progress in the Chemistry of Organic Natural Products, 103, pp. 103-131. doi: 10.1007/978-3-319-45541-9_4.
    9. National Center for Biotechnology Information (2025) PubChem Compound Database. Bethesda: U.S. National Library of Medicine. Available at: https://pubchem.ncbi.nlm.nih.gov (Accessed: 29 July 2026).
    10. Pertwee, R.G. (2008) 'The diverse CB1 and CB2 receptor pharmacology of three plant cannabinoids: delta-9-tetrahydrocannabinol, cannabidiol and delta-9-tetrahydrocannabivarin', British Journal of Pharmacology, 153(2), pp. 199-215. doi: 10.1038/sj.bjp.0707442.
    11. Russo, E.B. (2011) 'Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects', British Journal of Pharmacology, 163(7), pp. 1344-1364. doi: 10.1111/j.1476-5381.2011.01238.x.
    12. Sachse-Seeboth, C. et al. (2009) 'Interindividual variation in the pharmacokinetics of delta-9-tetrahydrocannabinol as related to genetic polymorphisms in CYP2C9', Clinical Pharmacology & Therapeutics, 85(3), pp. 273-276. doi: 10.1038/clpt.2008.213.
    13. UK Government (2018) The Misuse of Drugs (Amendments) (Cannabis and Licence Fees) (England, Wales and Scotland) Regulations 2018. London: The Stationery Office.
    14. Watanabe, K. et al. (2007) 'Cytochrome P450 enzymes involved in the metabolism of tetrahydrocannabinols and cannabinol by human hepatic microsomes', Life Sciences, 80(15), pp. 1415-1419. doi: 10.1016/j.lfs.2006.12.032.
    Important: This page is for education only. It is not medical advice. Cannabinoid research is still developing, and many studies have been done in cells or animals rather than people. Always speak to your prescriber before changing your treatment. PatientsCann UK does not recommend any specific cannabis product.