Skip to content


What is CBD and how does it work?


Cannabis scientist


Cannabidiol (CBD) is the second most prevalent active ingredient (the first being tetrahydrocannabinol or THC) in the cannabis plant (e.g., Cannabis sativa, Cannabis indica). CBD is an essential component of medical cannabis for therapeutic purposes. It can be derived from the hemp plant (containing less than 0.3% THC, making it a non-psychoactive variety of cannabis) or synthesised in a laboratory. CBD is one of several hundred components in cannabis and is considered a non-psychoactive compound, i.e., it does not result in a "high” such as with THC.

CBD belongs to a class of molecules called cannabinoids, which can activate specific receptors in our endocannabinoid system, which regulates critical bodily functions. There is some evidence pointing toward a calming effect produced by CBD, as well as anti-inflammatory and pain-relieving effects.

What impact does it have on our body?

The answer to this question is not necessarily straightforward. Some people report that CBD helps relieve anxiety and pain, while others claim it leads to better sleep. However, it is still difficult to understand its full impacts on the body due to insufficient, robust clinical studies.

CBD has been advertised for a wide variety of health issues; however, there is only sufficient evidence to support its effectiveness in treating some rare forms of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome. These conditions typically do not respond to antiseizure medications, but numerous studies have shown that CBD can reduce the number of seizures and, in some cases, even stop them altogether. CBD is also effective in treating multiple sclerosis-related muscle spasticity, but it is not used alone. Instead, it is combined with THC, a psychoactive molecule that can make you feel "high."

How does CBD oil affect the thyroid?

There have been numerous studies evaluating the impact of CBD on the thyroid. However, there is insufficient evidence to suggest that CBD has a positive impact on certain thyroid conditions. In 2022, the European Food Safety Authority (EFSA) issued a statement concluding that the oral ingestion of CBD may affect the body’s endocrine system. As per the currently available literature, these effects are only observed at exceptionally high levels of exposure, and further studies are needed to reach a robust conclusion.

How does CBD oil affect the liver?

This is currently a significant topic. Both EFSA and the U.S. Food and Drug Administration (FDA) have raised several concerns about CBD as an ingredient in food and drinks, citing potential liver damage as a possible side effect. However, while there is some evidence suggesting a potential risk of liver damage associated with CBD use, it appears to be relatively rare and more likely to occur at high doses, in individuals with underlying liver conditions, or when taken in combination with other drugs. This is why it is so essential that those taking prescription medicines consult with their doctor prior to incorporating CBD, or any other supplements, into their treatment.

What’s the safe dosage of CBD?

This is a difficult question. According to the World Health Organisation (WHO), CBD is generally well tolerated and has a good safety profile. Despite the lack of a robust database on CBD safety, there is no evidence of any public health-related problems associated with using pure CBD. In addition, CBD does not appear to have abuse potential.

Until very recently, I would have answered 70 mg/day. However, the United Kingdom (UK) Food and Safety Authority (FSA) reduced this level from 70 to 10 mg/day on the 12th October 2023. Based on my own research and experience in the cannabis industry, this seems to be a very conservative level for a healthy adult. However, CBD can be found in many different product formats, and the raw materials can vary drastically depending on its source and manufacturing processes. As a consequence, these variables can result in unique safety profiles and corresponding differences in Acceptable Daily Intakes.

What can we do if we feel like we’re being negatively affected?

CBD differs from other cannabinoids since it does not produce the usual psychoactive effects such as the “high” from THC. Although it is generally well-tolerated, high doses of CBD can result in side effects such as nausea, fatigue, and diarrhoea. Furthermore, CBD can impact the metabolism of other medications by competing with liver enzymes responsible for metabolising these drugs. Interestingly, consuming grapefruit can also affect how certain medications work in your body. Even though these symptoms are considered rare, please consult your physician if you experience adverse side effects from CBD use.

Are there any other things we can try if we are worried about CBD and its negative impacts?

All forms of medication, whether natural or not, may have some adverse side effects. The balance that needs to be struck is the benefit-to-risk ratio, i.e., what is the potential benefit of a substance compared to the risks associated with it? Seeking guidance from a licensed healthcare professional will give you access to informed choices of the various treatment options, including the benefits and risks.

If you found this blog interesting, download Cristelle’s whitepaper on CBD and Liver Toxicology, ‘Does CBD really harm the liver?’ here.