THC vs. CBD: differences between key cannabinoids
The cannabis plant is a botanical marvel that houses a wide range of molecules with therapeutic potential. Of the 480+ natural molecules found within cannabis, there are perhaps none more important than cannabinoids. In fact, these molecules are so prominent that the system they interact with in the body is named after them.
The endocannabinoid system (ECS) is a complex network of cannabinoid receptors (e.g. CB1 and CB2 receptors) located throughout the body. The human body is also capable of producing its own cannabinoids (i.e. endocannabinoids) that interact with this system to stimulate a wide range of vital functions. The ECS is responsible for maintaining homeostasis and achieves this by regulating memory, mood, appetite, pain, sleep, body temperature and immune responses.
The efficacy of medicinal cannabis products is a result of the interaction between the ECS and the cannabinoids found in cannabis plants (i.e. phytocannabinoids). THC (Δ9-tetrahydrocannabinol) and CBD (cannabidiol) are the most abundant and clinically relevant phytocannabinoids. As such, you will often see comparisons between the two. While they share some similarities, THC and CBD interact with the ECS in different ways, resulting in unique effect profiles.
THC is perhaps the most well-renowned cannabinoid. The reason being, THC produces psychoactive effects through its interaction with the ECS. CB1 receptors located in the brain (and spinal cord) are directly stimulated by THC, resulting in the sensations associated with the cannabis “high”.
The structure of the THC molecule is identical to the neurotransmitter anandamide, which is also an endocannabinoid. Anandamide is responsible for the “runner’s high” that can be experienced after intense exercise and THC mimics this effect when interacting with CB1 receptors.1 Feelings of euphoria and relaxation are the most commonly reported benefits associated with the THC-mediated activation of CB1 receptors. THC’s interaction with both CB1 and CB2 receptors may also produce analgesic, anti-inflammatory, antiemetic, appetite-stimulating, and sedative effects.2
CB1 receptors also regulate functions such as movement, memory, cognition, and sensory perception. Over-stimulation of these functions caused by THC use may result in short-term side effects, such as impaired coordination, memory recall, and reaction times.3 Other potential short-term effects include an increase in heart rate or anxiety. It is recommended that patients monitor their symptoms and safely titrate the dose of THC-containing products to reduce the risk of encountering unwanted side effects.
Some of the conditions that THC has displayed promise in managing include:
· Chronic pain
· Muscle spasticity
· Insomnia & other sleep disorders
· Nausea and vomiting
· Suppressed appetite
· Crohn’s disease
· Irritable bowel syndrome (IBS)
CBD is a cannabinoid that is well-renowned for a different reason – its safety profile. Unlike THC, CBD does not directly stimulate the CB1 or CB2 receptors that comprise the ECS. Instead, CBD encourages the natural production and actions of endocannabinoids, such as anandamide.4
CBD also inhibits the activity of CB1 receptors, which means that its effects are non-intoxicating and will not get you “high”. In doing so, CBD is also able to reduce the potency of THC’s psychoactive effects.5 CBD-based products are a popular choice amongst patients who require some of medicinal cannabis’ therapeutic benefits without impairments to their daily functioning.
Although CBD is not as potent as THC, it can still contribute to a wide range of health benefits through its analgesic, anti-inflammatory, and anti-convulsant properties.6 CBD possesses a good safety profile with a low risk of encountering adverse effects. However, CBD has the potential to interact with other prescription medications, so it is recommended that patients consult with their healthcare professional before using CBD-containing products.
Some of the conditions that CBD has displayed promise in managing include:
· Some forms of epilepsy
· Chronic pain
· Nausea and vomiting
· Substance addiction
Medicinal cannabis products contain varying ratios of THC and CBD. The product format and cannabinoid content have an impact on patient outcomes due to having different therapeutic and side effect profiles.
Research has shown that the synergy between THC, CBD, and other phytochemicals (e.g. terpenes and minor cannabinoids) can provide a wider range of benefits than isolated cannabinoid preparations.7 Inhalable formats (e.g. dried medicinal cannabis flower and vaporiser oils) facilitate the combined consumption of these compounds and have rapid onset times (e.g. 1-10 min) to provide instant relief.
Capsules and lozenges are both consumed orally. Capsules can contain full-spectrum cannabis extracts (i.e. THC, CBD, and other phytochemicals), broad-spectrum cannabis extracts (i.e. no THC), or isolated cannabinoids. They have a longer duration than inhalable formats (e.g. 4-12 hours) but a slower onset time (e.g. 30-90 min).8
Oils and sprays are both consumed sublingually. Like capsules, they can either contain full-spectrum extracts, broad-spectrum extracts, or isolated cannabinoids. They have the longest duration of all product formats (e.g. 12-24 hours) and relatively quick onset times (e.g. 5-30 min).8
In Australia, medicinal cannabis products that have a CBD content of 98% or more (where the content of other cannabinoids is less than 2%) are classified as Schedule 4 Prescription Only medicines. Any products with a THC content greater than 2% of their total cannabinoid content are classified as Schedule 8 Controlled Drugs.9
Aside from Epidyolex (an oral CBD oil) and Sativex (an oral THC:CBD spray), medicinal cannabis products are not registered medicines in Australia. However, patients can still access CBD and THC-containing medicinal cannabis products through the Special Access Scheme B (SAS-B)10 and Authorised Prescriber (AP) pathways.11 If you believe THC or CBD may be beneficial for your condition, book a consultation with your doctor to see if you are eligible to access these medicines.
1. Pertwee, R. (2008). The diverse CB1 and CB2 receptor pharmacology of three plant cannabinoids: Δ9-tetrahydrocannabinol, cannabidiol and Δ9-tetrahydrocannabivarin. British Journal of Pharmacology [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2219532/ [accessed 11 March 2022].
2. Zou, S., Kumar, U. (2018). Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System. Internation Journal of Molecular Science [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5877694/ [accessed 11 March 2022].
3. Kroon, E., Kuhns, L., Cousijn, J. (2021). The short-term and long-term effects of cannabis on cognition: recent advances in the field. Current Opinion in Psychology [online]. Available from: https://www.sciencedirect.com/science/article/pii/S2352250X20301135 [accessed 11 March 2022].
4. Leweke, FM., et al. (2012). Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia. Translational Psychiatry [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3316151/ [accessed 11 March 2022].
5. Lapraire, RB., et al. (2015). Cannabidiol is a negative allosteric modulator of the cannabinoid CB1 receptor. British Journal of Pharmacology [online]. Available from: https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bph.13250 [accessed 11 March 2022].
6. Pisanti, S., et al. (2017). Cannabidiol: State of the art and new challenges for therapeutic applications. Pharmacology & Therapeutics [online]. Available from: https://www.sciencedirect.com/science/article/abs/pii/S0163725817300657 [accessed 11 March 2022].
7. Russo, E. (2011). Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British Journal Pharmacology [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3165946/ [accessed 11 March 2022].
8. Grotenhermen, F. (2003). Pharmacokinetics and pharmacodynamics of cannabinoids. Clinical Pharmacokinetics [online]. Available from: https://pubmed.ncbi.nlm.nih.gov/12648025/ [accessed 11 March 2022].
9. Australian Government Federal Register of Legislation. (2022). Poisons Standard February 2022 [online]. Available from: https://www.legislation.gov.au/Details/F2022L00074 [accessed 16 March 2022].
10. Therapeutic Goods Administration. (2021). Special Access Scheme [online]. Available from: https://www.tga.gov.au/form/special-access-scheme [accessed 11 March 2022].
11. Therapeutic Goods Administration. (2021). Authorised Prescribers [online]. Available from: https://www.tga.gov.au/form/authorised-prescribers [accessed 11 March 2022].
Learn about the different standards used to ensure medicinal cannabis is safe in Australia