CBD oil is increasingly popular, both as a food supplement and for topical use. We asked dietitian Emer Delaney to explain what it is, why people use it and whether it's safe.


What is CBD oil?

Cannabis sativa, the flowers of which are also known as marijuana, is a plant that contains many chemicals. One of these substances, cannabidiol (CBD) has gained widespread popularity in the health world. This chemical compound acts throughout the body, including on certain parts of the brain.

CBD is different from tetrahydrocannabinol (THC) – also a substance from the cannabis plant. The latter is responsible for the 'high' typically associated with marijuana. CBD, however, is non-intoxicating, and some believe it may have potential health benefits. Once extracted from the cannabis plant, CBD is diluted with a carrier oil, such as olive or coconut oil, to improve its bio-availability.

The Food Standards Agency has just updated its advice to recommend that people don't consume more than 10mg of CBD a day (the equivalent of 4-5 drops of 5% CBD oil). Some products available on the UK market will have a daily dose recommendation above this, so check labels carefully.

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Contrary to popular belief, CBD oil is legal in the UK, as it is not a controlled substance. There are, however, strict restrictions over its THC content. CBD oil that isn't medically prescribed can only have a maximum THC content of 0.2%. CBD oil products that have a higher THC content may be available to buy online, but not legally.

A small number of patients in the UK may be prescribed a cannabis-based medicine to treat epilepsy or nausea during chemotherapy. Visit the NHS website for more information on medical cannabis.

It’s worth noting that there are no CBD products authorised for use in animals in the UK. If you are considering CBD oil for your pet, only a vet can prescribe a legal human CBD product.

What is CBD oil used for?

Supporters of CBD oil believe it may help a number of clinical conditions. However, there are few licensed products available in the UK, and caution should be exercised if considering the use of over-the-counter products.

CBD oil is often considered for the following conditions:

1. Chronic pain

CBD oil is often used for chronic pain, because the human body has a system called the endocannabinoid system that helps regulate pain. The body produces natural substances called endocannabinoids, which bind to special receptors in the body and help reduce pain sensations. CBD oil works by interacting with these same receptors, which is why it’s thought to be helpful.

Although studies (such as one in 2022) report that CBD maybe a useful alternative to opioids for pain management, there are currently no licensed cannabis-based products on the market in the UK. This is because the current evidence is not sufficient, and there is a lack of fully tested randomised controlled trials.

2. Epilepsy

A systematic review looking at the use of CBD for epilepsy concluded that there is insufficient evidence to support the efficacy and long-term safety of using it to treat epilepsy.

Some trials, however, have suggested it may be effective in drug-resistant epilepsy (refractory epilepsy), and for this reason, patients with certain types of the condition (including Dravets syndrome and Lennox-Gastaut syndrome) may be prescribed CBD.

For other types of epilepsies, the UK recommendation is that – at present – there is either no or very little evidence showing any benefit with CBD. Further randomised, placebo-controlled studies are needed.

3. Multiple sclerosis (MS)

Evidence supports the use of CBD for reducing pain and muscle spasms in people with with MS-related spasticity. There is, therefore, a licensed product available in the UK that should be used in preference to unlicensed products.

4. Osteoarthritis

Topically applied CBD has shown some promise in animal studies for reducing inflammation and pain associated with osteoarthritis. Human studies have also found associations between CBD use and improvements in patients’ arthritis symptoms, even with reductions in their other medications. However, it has been difficult to attribute the therapeutic benefits to CBT alone.

5. Anxiety and depression

Early evidence looking into the use of CBD in the treatment of anxiety and depression has found some exciting results, although on very small samples or using animal models.

One study assessed anxiety links with public speaking; it found a very specific dose of CBD (300mg) showed anti-anxiety effects. A second study was a standalone case report of one child with post-traumatic stress disorder (PTSD). It found CBD oil helped the child safely reduce her anxiety and improve sleep.

6. Acne

CBD may also have the potential to help reduce acne; this may be because of its anti-inflammatory properties. However, it is important to note that this research is still in its infancy and more studies are needed.

Can I buy CBD oil safely?

Most large health food stores will stock 'pure' CBD oil. However, as it is classed as a 'food supplement' rather than a 'medicinal product', it isn't regulated in the UK, and in most cases lacks the appropriate clinical studies to support many of its claims. This lack of regulation also means you cannot know for sure that the product you buy contains the 'active' ingredients at the amounts listed on the label. Furthermore, the product may contain contaminants such as pesticides, heavy metals and other elements. For this reason, the NHS highlights there is no guarantee that these products will be of good quality or provide the intended health benefits.

Is CBD oil safe for everyone?

If you're considering using CBD oil, you should speak to your GP or other healthcare professional to ensure that it is safe and appropriate for you to do so.

This is particularly important if you are experiencing any concerning symptoms, if you have any pre-existing conditions or if you are taking any medication including statins, blood-thinning medication and calcium channel blockers. CBD oil should not be used by pregnant or breastfeeding women.

The recommended limit on consumption of CBD is due to research suggesting that the more CBD you consume over a lifetime, the greater your risk of longterm side effects – particularly to your liver or thyroid.

Although the use of CBD is controversial, it does seem to be tolerated by most people. It has, however, caused hypotension and light-headedness, as well as other side effects such as dry mouth, diarrhoea, reduced appetite and fatigue.

The oil does not contain the THC part of the cannabis plant, so the oil will not induce a ‘high’.

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Last updated: 23 October 2023.

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