CBD oil – its uses and side effects

Cannabis and products derived from cannabis such as CBD oil and Sativex (a mixture of the main active ingredients of cannabis - THC and CBD which is used to treat multiple sclerosis and cancer pain), are very much in the news lately and are being marketed strongly online, in health shops and elsewhere.

These cannabis products are known for their ability to affect our own cannabis receptors CB1 and CB2 as well as a number of our other cannabinoid like receptors, such as GPR018, GPR55 and PPAR-y. As a result of being able to target multiple types of receptor within our own body, cannabis and its products can have a wide range of effects. For more on our cannabinoid receptors please read the article on the endocannabinoid system.

Cannabis related plants

Marijuana and hemp both refer to the cannabis sativa plant and are the best known members of the cannabis family of plants.

  • Marijuana - The term cannabis, when talking about the recreational drug, normally refers to a particular subspecies of the cannabis sativa plant. This is more accurately called marijuana.
  • Hemp - There is a related subspecies of Cannabis sativa which produces hemp, which is much lower in THC, the psychoactive ingredient of marijuana. Historically hemp has been used to produce rope and edible oils.
  • Cannabis indica is another species of the cannabis family. Indica is less able to induce the high of Cannabis sativa and instead produces a dopey “stoned” euphoria.
  • Cannabis ruderalis. Yet another species of cannabis is not very strong, but its effects are possibly similar to those of Cannabis indica.

Cannabinoid products

The two best known chemicals found in the cannabis and hemp plants are THC – tetrahydrocannabinol and CBD – cannabidiol. However there are a number of other compounds found within the cannabis and hemp plants which can modify its effects on us.

There are also synthetic cannabinoids that have been produced in laboratories, some for pain relief such as paracetamol, and some for research purposes. Unfortunately some of those produced for research purposes have entered the public domain, mainly in the form of the illicit drug “spice” which is normally composed of herbs which have been sprayed with these synthetic compounds. Sometimes spice is sold as a super strong liquid. These synthetic compounds have an increased danger of side effects, with products like spice having a much stronger effect on us and compatibility with our bodies than most natural products.

1 - THC [tetrahydrocannabinol]

THC was discovered in 1964. It is the psychoactive component of cannabis responsible for the high that cannabis users get. It is also mainly responsible for any dependency that drug users may experience. It is predominantly active at CB1 receptors in the brain.

2 - CBD [cannabidiol]

Cannabidiol was discovered in 1940, quarter of a century before THC. It differs from THC in that instead of acting directly on a cannabinoid receptor such as CB1 it acts indirectly in at least three different ways:

  • It blocks an enzyme found inside the cells of our nervous system called FABP. This enzyme, FABP moves our own endogenous cannabinoid anandamide inside each cell to another enzyme called FAAH which breaks it down. As such when FABP is blocked our anandamide can’t be broken down as easily and anandamide levels outside the cell remain higher.
  • It enhances the activities of GABA releasing neurons. Given that GABA is a chemical that has a calming influence on us, this explains some of the calming qualities of CBD oil.
  • It also stimulates the production of 2-AG, the other of our two most important endocannabinoids (anandamide and 2-AG).

CBD is not potentially addictive like THC and as such has been legalized in most jurisdictions.

The ingestion of CBD results in a slew of effects, many of which are beneficial, such as relief from pain and anxiety. Other benefits include reducing appetite, which is in contrast to THC, which increases appetite. CBD also reduces acne, improves sleep and has dramatic effects on some forms of epilepsy, especially those experienced in childhood and some which do not respond to any standard anti-seizure medications.

3 – Acetaminophen [Paracetamol]

Paracetamol breaks down into a substance named AH404 which prevents the breakdown of our own pain-relieving endocannabinoids, thus providing pain relief. It also affects a number of other systems such as COX and TRPV, and as such has a wider range of side effects than CBD oils.

Potential side effects of CBD oil

CBD is known to cause diarrhoea and fatigue in some people. It can also affect appetite, normally reducing it which is probably fine if you are looking to reduce weight.

CBD can also interact with some anti-epileptic medications, and so for epileptics taking CBD oil it is important to get professional advice as to the quantity of CBD oil to take and how to adjust the dose of your anti-epileptic medications.

Despite the cautionary note I’ve added below, CBD oil has a pretty low rate of side effects. For instance in comparison to opiate pain relieving medications it appears very much safer and importantly seems to almost never lead to addiction.


CBD oil affects the efficiency of our liver’s detoxification pathway using the enzyme CYP450. Around 60% of prescription drugs use this route. As such anyone on prescription medicine should consider the implication that their medicine could be more effective at lower doses and also last for longer in their system. Most prescription medicines are dangerous at higher levels than those specifically prescribed and so checking with your GP is strongly advised.

To place this into context the CYP450 pathway is also affected in a similar fashion by citrus fruits, particularly lime, lemon and grapefruit. As such the ingestion of these citrus fruits, especially in juice form should be moderated when taking any supplements or oils that contain CBD.

CBD can also interact with other cannabinoids such as THC by enhancing their effects.

Some conditions that may benefit from cannabinoids

  • Pain Relief – The use of the drug Sativex for neuropathic pain, whether caused by Multiple Sclerosis – MS, Rheumatoid Arthritis or Cancer is well established. Sativex is a mix of THC and CBD. It is probably a better choice than the standard arsenal of drugs generally used by the medical profession for pain management. This standard arsenal includes opiates (currently in the news as causing massive levels of over dependency in the US and UK), anti-depressants, which have their own set of problems and anticonvulsants.
  • Anxiety and depression – Studies with adults have shown CBD oil to be able to reduce anxiety and possibly depression also. The effects on anxiety have been quite significant and include improvement in sleep as well. The doses that reduce anxiety are around 4mg/kg bodyweight per day. Larger and smaller doses are more likely to have adverse effects on anxiety, showing there is a sweet spot for CBD dosing if you suffer with anxiety. Note also that the other main cannabis derived cannabinoid, THC generally increases anxiety.
  • Cancer – CBD oil has been shown to reduce cancer caused weight loss (cachexia), nausea and pain in those receiving chemotherapy. It has also been found to actually kill many types of cancer cells when tested in test tubes. In particular breast and prostate cancer cells have been killed by CBD administration. In addition it can relieve pain due to cancer and as such is a promising drug for use with many cancers.
  • Crohn’s disease and colitis – Together these inflammatory bowel diseases (IBDs) have been found to respond well to cannabinoid treatments. Symptoms experienced with IBDs that respond well to CBD include diarrhoea, tummy pains and loss of appetite (1).
  • Alzheimer’s – There is evidence that THC can reduce the beta amyloid plaques and other inflammatory markers inside neurons that are a hallmark of Alzheimer’s disease (2). Beta amyloid may not be as important a marker for Alzheimer’s as tau protein however. As with all interventions the end result of reversal of cognitive decline and behavioural changes are the litmus test for whether CBD or THC could actually help with dementia. Another study using CBD on Alzheimer’s in mice found that memory of faces was retained (3). This suggests that CBD could possibly help somebody with Alzheimer’s recognize their family members until the end.
  • Parkinson’s - There are studies also of Parkinson’s and CBD and cannabis use. There have been a number of observational studies that appear to show improvement in both motor and non-motor symptoms of Parkinson’s when patients use CBD or other cannabis related products (4).
  • Heart health and Diabetes – CBD causes widening of the arteries in many studies and protects against blood vessel damage due to high blood sugar levels as occurs in diabetes (5).
  • Autism – Studies with autistic kids have shown that CBD oil can perform as well as the best conventional treatments. For instance it can have the same effect on hyperactivity as Ritalin (6).
  • Rheumatoid Arthritis – A study in rats showed a reduction in swelling around the joints and also in movements associated with arthritic pain when using CBD oil on the skin. (7)
  • Multiple Sclerosis – MS can cause spasticity, inflammation and depression. The first two of these symptoms have been shown in a number of studies to be relieved by CBD oil usage (8).

As you can see from the above list, the range of conditions that could be addressed by CBD oil is vast (9). There is currently a lack of quality research into many of them, but research is ongoing and results remain promising.

Which CBD oils can you trust?

CBD oils sold commercially in health food shops, online and through other outlets are extremely variable in quality and price. For instance there can be a greater than tenfold difference in the amount of CBD present in different products. Also prices for a given amount of CBD vary by at least a factor of 5. In addition up to 70% of CBD products sold in the US have been found to inaccurately state the dose of CBD present in the product.

Added to these variabilities is the fact that a consumer test last year showed that around 70% of CBD products did not actually contain the amount of CBD that was advertised on the label.

To check what exactly you are supposedly getting do make sure the label tells you the amount of CBD rather just a generic term like cannabinoids, which could include a host of other chemicals.

So is CBD oil worth buying?

CBD oil has a good safety profile as far as current research is concerned, with few side-effects. It seems to benefit a large number of diseases and malaises. I would caution against using it for any old pain or gripe. Instead consider using it if you suffer from any of the problems identified above. There are a large number of other problems I have not mentioned which may also benefit from CBD oil, but remember that these are still quasi drugs and will affect the way in which your body can achieve balance. In a perfect world your body will not be reliant on CBD oil or indeed any other drug, so use it with caution.


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388177/ How cannabinoid treatments can improve symptoms for those with intestinal bowel diseases.
  2. https://www.salk.edu/news-release/cannabinoids-remove-plaque-forming-alzheimers-proteins-from-brain-cells/ THC counters inflammation in neurons associated with Alzheimer’s
  3. https://www.ncbi.nlm.nih.gov/pubmed/25024347 Long term CBD usage in mice improves social recognition in models of Alzheimer’s
  4. https://www.liebertpub.com/doi/full/10.1089/can.2017.0002 Italian review of the studies on CBD and Parkinson’s up to the year – 2017 also https://journals.sagepub.com/doi/abs/10.1177/0269881114550355 Parkinson’s
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3579247/ Review of studies showing benefit using cannabinoids for cardiovascular disease and diabetes.
  6. https://www.frontiersin.org/articles/10.3389/fphar.2018.01521/full Autism and CBD.
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4851925/. A study on rats using CBD for arthritis.
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874292/. A summary of studies showing the benefits of CBD oil for Multiple Sclerosis.
  9. https://www.healthline.com/nutrition/cbd-oil-benefits Referenced information about 7 of the benefits of CBD oil.

Photo courtesy of Jhon David