As a medical cannabis patient, the amount of new information can feel overwhelming. There are a lot of new terms and concepts, and it is important to have an understanding of these. A solid foundational knowledge allows for better communication with doctors, pharmacists, and other health care practitioners. Let’s take a look at some of the key elements.


What are THC and CBD?

THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol) are produced by the cannabis plant. They are the main active ingredients found in cannabis, and belong to a group of molecules called cannabinoids1. Interestingly, they are not naturally produced by cannabis, instead they are formed through a process known as decarboxylation 2.

In nature, THC and CBD exist as acidic versions of themselves called THCA and CBDA, and when  cannabis is heated through smoking, vaporizing, cooking or baking the “acidic” portion of the THCA and CBDA molecule (known as a carboxyl) is removed,  forming THC and CBD respectively 2.

It is important to note that our ingestible oils and vape concentrates come pre-activated which means they do not need to be activated through heating before use.

How are Cannabinoids interacting with the Body?

Over 100 different types of cannabinoids are produced by the cannabis plant 1, with THC and CBD being the most abundant. Although THC and CBD are both cannabinoids, when consumed they act very differently in the body.

THC is the main cannabinoid responsible for the feeling of intoxication, commonly known as a “high” 3. THC interacts with the body’s endocannabinoid system (ECS) by activating cannabinoid receptors called CB1 and CB2. The ECS is an ancient signaling system and is responsible for helping regulate cognitive and physiological processes, memory, fertility, mood and appetite, among other functions 4. THC activates these receptors by binding to them in a manner that is similar to a lock and key, when this occurs changes happen in the body .

Understanding THC and CBD cannabinoids in cannabis plants 1

THC activates cannabinoid receptors in the body through a lock and key mechanism.

CBD is a non-intoxicating cannabinoid 1,3, although when vaporized at high doses (400 mg) one study found CBD to be mildly intoxicating . Similar to THC, CBD interacts with the ECS, however it does so in a different manner. As a result, CBD is thought to help counter some of the unwanted side-effects felt from THC such as anxiety 3,6,7. In addition to the ECS, CBD also exerts its effects in the body by interacting with other signaling pathways 8.


Does the Ratio of THC to CBD matter?

Different cannabis products have different ratios of THC to CBD. Some are THC dominant, others CBD dominant, and still others are more balanced in their ratio. But what exactly does this mean?

Understanding the differences between these product types is important as the ratio of THC to CBD will influence the effectiveness and risk of encountering unwanted side effects from each product.


Product Type Ratio THC to CBD Ratio
THC Dominant
High in THC / Low in CBD

Dried Flower: Henik, Holden, Williston, Walker, Great Bear, Mohawk, Bienville, Sachigo, Grower’s Blend

Oil with Dosing Syringe: 20:1

Oral Spray: 20:1

Capsule: 6:0 and 10:0

Vapes: Aspen and Walker

Comparable amounts  of THC and CBD

Dried Flower: Churchill

Oil with Dosing Syringe: 10:13

Oral Spray: 10:13

Capsule: 6:8 and 10:13

Vapes: Churchill

CBD Dominant
High in CBD /  Low in THC

Dried Flower: Treasure Island

Oil with Dosing Syringe: 1:25

Oral Spray: 1:25

Capsule: 1:15 and 1:25


DID YOU KNOW? CBD dominant products still contain small amounts of THC. This means individuals working in worksafe positions may still test positive for THC during random drug screening and should speak with their employer before using cannabis 9.


How to Help Prevent Unwanted Side-Effects?

In general, unwanted side effects from cannabis (i.e. dizziness, increased heart rate, and fatigue) are due to the amount of THC consumed 3,10. Interestingly, studies are beginning to emerge which show that CBD can decrease unwanted side effects caused from THC3. Although further research is still needed to understand this interaction, Canada’s lower risk cannabis use guidelines recommends using products which contain lower amounts of THC or a higher ratio of CBD to THC (i.e. balanced or CBD dominant products)11.


Selecting the Right Ratio can help Predict Therapeutic Effects

Both THC and CBD contribute to the therapeutic effects of cannabis. The type and ratio of cannabinoids present in a product can help to determine its benefits. Research indicates that THC dominant, CBD dominant and THC:CBD balanced products can be helpful for treating certain diseases and/or symptoms including the following:


Therapeutic Use*

CBD dominant

THC dominant Balanced


Suppression of nausea and vomiting as a result of chemotherapy



Improvement of symptoms resulting from multiple sclerosis and spinal cord injury






Pain such as chronic non-cancer or neuropathic pain








Sleep Disorders







* This table has been provided for informational purposes only and is not intended to be used for product selection purposes.

When considering using Cannabis for medicinal purposes it is important to first speak with your doctor so that a proper assessment and diagnosis can be made. It is also important to let your doctor know which types of medication you are taking, as THC and CBD can interact with certain drugs.



  1. Health Canada (2019) About Cannabis.
  2. Solymosi, K., & Koefalvi, A. (2017). Cannabis: a treasure trove or pandora’s box?. Mini reviews in medicinal chemistry, 17(13), 1223-1291.
  3. Health Canada (2019) What you need to know if you choose to consume cannabis. Electronic document,, accessed February 2020.
  4. Health Canada (2018) Information for Health Care Professionals.
  5. Solowij, N., Broyd, S., Greenwood, L. M., van Hell, H., Martelozzo, D., Rueb, K., … & Murray, R. (2019). A randomised controlled trial of vaporised Δ 9-tetrahydrocannabinol and cannabidiol alone and in combination in frequent and infrequent cannabis users: acute intoxication effects. European archives of psychiatry and clinical neuroscience269(1), 17-35.
  6. Robson, P. J. (2014). Therapeutic potential of cannabinoid medicines. Drug testing and analysis6(1-2), 24-30.
  7. Zuardi, A. W., Shirakawa, I., Finkelfarb, E., & Karniol, I. G. (1982). Action of cannabidiol on the anxiety and other effects produced by Δ 9-THC in normal subjects. Psychopharmacology76(3), 245-250.
  8. White, C. M. (2019). A review of human studies assessing cannabidiol’s (CBD) therapeutic actions and potential. The Journal of Clinical Pharmacology59(7), 923-934.
  9. Spindle, T. R., Cone, E. J., Kuntz, D., Mitchell, J. M., Bigelow, G. E., Flegel, R., & Vandrey, R. (2019). Urinary Pharmacokinetic Profile of Cannabinoids Following Administration of Vaporized and Oral Cannabidiol and Vaporized CBD-Dominant Cannabis. Journal of analytical toxicology.
  10. MacCallum, C. A., & Russo, E. B. (2018). Practical considerations in medical cannabis administration and dosing. European journal of internal medicine49, 12-19.
  11. Fischer, B., Russell, C., Sabioni, P., van den Brink, W., Le Foll, B., Hall, W., Rehm, J. & Room, R. (2017). Lower-Risk Cannabis Use Guidelines (LRCUG): An evidence-based update. American Journal of Public Health, 107 (8). DOI: 10.2105/AJPH.2017.303818.—reports-and-books—research/canadas-lower-risk-guidelines-cannabis-pdf.pdf
  12. Meiri E, Jhangiani H, Vredenburgh JJ, Barbato LM, Carter FJ, Yang HM, Baranowski V. Efficacy of dronabinol alone and in combination with ondansetron versus ondansetron alone for delayed chemotherapy-induced nausea and vomiting. Curr Med Res Opin 2007 03;23(1473-4877; 0300-7995; 3):533-43.
  13. Elder JJ, Knoderer HM. Characterization of dronabinol usage in a pediatric oncology population. J Pediatr Pharmacol Ther 2015 Nov-Dec;20(6):462-7.
  14. Musty and Rossi (2001) Effects of smoked cannabis and oral delta-9-tetrahydrocannabinol on nausea and emesis after cancer chemotherapy: A review of state clinical trials. Journal of Cannabis Therapeutics 1(1): 29-56.
  15. Vaney et al. (2004) Efficacy, safety and tolerability of an orally administered cannabis extract in the treatment of spasticity in patient with multiple sclerosis: a randomized, double-blind placebo controlled crossover study. Multiple Sclerosis 10:417-424.
  16. Flachenecker et al. (2014) Nabiximols (THC/CBD Oromucosal Spray, Sativex ®) in clinical practice -results of a multicenter non-interventional study (Move 2) in patients with multiple sclerosis spasticity. European Neurology 71:271-279.
  17. Freidel et al. (2015) Drug resistant MS spasticity treatment with Sativex ® add-on and driving ability. Acta Neurologica Scandinavia 131:9-16.
  18. Ferre et al. 2016. Efficacy and safety of nabiximols (Sativex ®) on multiple sclerosis spasticity in a real-life Italian monocentric study. Neurol Sci 37:235-242.
  19. Bloom et al. (2012) Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial. CMAJ 184(10): 1143-1150.
  20. Wilsey B et al. (2016) An exploratory human laboratory experiment evaluating vaporized cannabis in the treatment of neuropathic pain from spinal cord injury and disease. J Pain 17(9):982-1000
  21. Devinsky et al. (2016) Cannabidiol in patients with treatment-resistant epilepsy: An open-label interventional trial. Lancet Neurol 15(3):270-8.
  22. Devinsky et al. (2017) Cannabidiol in Dravet Syndrome Study Group. Trial of cannabidiol for drug-resistant seizures in the dravet syndrome. N Engl J Med 376(21):2011-20
  23. Devinsky et al. (2018) Effect of cannabidiol on drop seizures in the lennox-gastaut syndrome. N Engl J Med 378(20):1888-97.
  24. Tzadok et al. (2016) CBD-enriched medical cannabis for intractable pediatric epilepsy: The current israeli experience. Seizure 35:41-4.
  25. Svendsen et al. (2004). Does the cannabinoid dronabinol reduce central pain in multiple sclerosis? Randomized double blind placebo controlled crossover trial. BMJ 329:253-60.
  26. Rog et al. (2005) Randomized, controlled trial of cannabis-based medicine in central pain in multiple sclerosis. Neurology 65: 813-819
  27. Nurmikko et al. (2007). Sativex successfully treats neuropathic pain characterised by allodynia: A randomised, double-blind, placebo-controlled clinical trial. Pain 133: 210-20
  28. Hoggart et al. (2015) A multicentre, openlabel, follow-on study to assess the long-term maintenance of effect, tolerance and safety of THC/CBD oromucosal spray in the management of neuropathic pain. J Neurol 262(1):27-40
  29. Wilsey B, Marcotte T, Tsodikov A, Millman J, Bentley H, Gouaux B, Fishman S. A randomized, placebo-controlled,crossover trial of cannabis cigarettes in neuropathic pain. J.Pain 2008 06;9(1526-5900; 1526-5900; 6):506-21.
  30. Wilsey B, Marcotte T, Deutsch R, Gouaux B, Sakai S, Donaghe H. Low-dose vaporized cannabis significantly improves neuropathic pain. J.Pain 2012 12/10;14(1528-8447; 1526-5900; 2):136-48.
  31. Flach AJ (2002) Delta-9-tetrahydrocannabinol (THC) in the treatment of end-stage open-angle glaucoma. Trans Am OphthalmolSoc 100:215-22.
  32. Tomida et al. (2006) Effect of sublingual application of cannabinoids on intraocular pressure: A pilot study. J Glaucoma 10: 349-53.
  33. Roitman et al. (2014) Preliminary, Open-Label, Pilot Study of Add-On Oral ∆9-Tetrahydrocannabinol in Chronic Post-Traumatic Stress Disorder. Clin Drug Investig 34:587-591.
  34. Brady et al. (2004) An open-label pilot study of cannabis-based extract for bladder dysfunction in advanced multiple sclerosis. Multiple Sclerosis 10:425-433.
  35. Whiting (2015) Cannabinoids for Medical Use: A Systematic Review and Meta-analysis. JAMA 313(24):2456-2473
  36. White, CM (2019) A review of human studies assessing cannabidiol’s (CBD) therapeutic actions and potential. The Journal of Clinical Pharmacology 59(7):923-934.
  37. Bergamaschi et al. (2011) Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naïve social phobia patients. Neuropsychopharmacology 36:1219-1226.
  38. Linares et al. (2018) Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Brazilian Journal of Psychiatry 41(1): 9-14.