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Cannabidiol, CBD Oil

Cannabidiol CBD Oil

Cannabidiol (CBD) oil has reached its presence in most pharmacies and supermarkets in the UK. It is widely available online and due to its coverage in media, it is growing in popularity.

CBD oil (also sold under name of hemp oil) is produced by extraction of cannabidiol from the hemp plant. Cannabidiol is one of over 100 cannabinoids that are present in the cannabis plant.

Hemp plants are normally used in the production of CBD oils as these are high in cannabidiol and do not contain tetrahydrocannabinol (THC) in large amounts. THC is the psychoactive cannabinoid that makes people ‘high’ when they use cannabis.

Quick FAQ

Is it possible to overdose on CBD oil?
It would be impossible to overdose on CBD oil due to the high tolerance of humans. According to one study, the deadly dose would be around 20,000 mg given all at once.

What Is CBD Oil Used For?

Most manufactures of CBD oil claim the following:

  • Reduce anxiety and stress and
  • Pain relief
  • Reduction in inflammation


THC and cannabidiol are currently widely researched for medical purposes and have shown to help possibly with anxiety.

A small study involving 72 patients who took CBD resulted in a reduction in patients’ anxiety and improved sleep.

A small number of patients however reported worsening of both symptoms throughout the duration of the trial (Shannon et al, 2019). Overall results proved ‘a more sustained response to anxiety than for sleepover time’ (ibid).

This study however had its limitations for example lack of randomization and a very small sample of patients. The antidepressant and anxiolytic properties of CBD oil is possibly due to its partial agonist properties for the serotonin 5-HT1A receptor (Russo et al, 2005).

No human studies involving CBD preparations exist to support its claimed anti-inflammatory properties, however, an animal study has shown a significant reduction in joint swelling in response to transdermal treatment with a gel containing CBD (Hammell et al, 2015).

The strongest evidence for cannabidiol effectiveness is in the reduction of seizures in Lennox-Gastaut syndrome (LGS), supported with a randomized, double-blind, placebo-controlled trials (French et al, 2017).

Why CBD Oil Is Placed Under The Tongue?

Placing CBD oil under the tongue allows for quicker absorption into your body as compared for example with oral ingestion. Sublingual absorption is very effective, and generally more products will be absorbed and available in your body.

Higher bioavailability increases the effectiveness of the product. That is why oil drops or spray formulations are preferable for CBD oil.

Is CBD Oil Legal In UK

CBD oil is legal in the UK, however, products containing CBD cannot contain more than 0.02% of THC. CBD oil cannot be advertised for medical purposes.

Does CBD oil get you ‘high’?

No. CBD oil sold in the UK cannot contain more than 0.02% of THC, the psychoactive cannabidiol which makes people ‘high’.

What are the common side effects of CBD oil?

Some studies identified the following side effects when taking CBD oils (SPS NHS, 2018):

  • Somnolence (sleepiness) ,
  • Decreased appetite,
  • Vomiting,
  • Diarrhea and
  • Elevated liver enzymes

Does CBD Oil Interact With Other Medications?

Like many other drugs, CBD oil is metabolized by the liver. In vitro studies (in the laboratory) suggest CBD oil is a potent inhibitor of different liver enzymes. Liver inhibitors can increase the plasma concentration of other drugs metabolized by the same enzyme.

Some interactions known to be reported with CBD oils include interactions with anticoagulants (e.g. warfarin) and antiepileptic medicines, however, the exact degree of interactions is not known.

You should inform your doctor if you are planning to use CBD oil and currently take other medications. For more information visit ‘Cannabis-based medicinal products potential drug interactions‘ (ibid).

What other cannabis/cannabidiol preparations are available in the UK?

The only licensed preparation containing both THC and CBD in the UK is Sativex, which contains a mix of THC and CBD. Sativex is only licensed for the treatment of spasticity in multiple sclerosis. Due to the high cost of this medication, NICE does not recommend prescribing it to patients.

I heard the news on Tv about medicinal Cannabis, what is it?

Epidiolex is currently going through a process of licensing approval. Epidiolex is a highly purified liquid containing CBD’ (NHS, 2018). Epidiolex does not contain THC. Epidiolex has already been approved in the USA for the treatment of two epilepsy disorders.

In the UK is can currently be prescribed as unlicensed medicine for the treatment of Lennox-Gastaut syndrome and Dravet syndrome (rare forms of epilepsy).


More research is needed to support the benefits claims and safety of CBD oil. Large, well-designed clinical studies would be preferable; however, this is unlikely to happen due to the costs involved and due to the fact that CBD oils are already sold as food supplements.

Understanding how CBD act in the body would be also beneficial since the mechanism of action of cannabidiol is not fully determined.

Quick FAQ

Is there an age limit to purchase CBD oil?
It depends on where you reside. To acquire CBD oil in many places, you must be 18 or 21 years old. Check the laws in your state.
Is CBD safe to consume when pregnant?
While pregnant or nursing, the FDA advises women not to consume cannabis or any CBD product. It might be harmful to you and your child.
  • French, J., Thiele, E., Mazurkiewicz-Beldzinska, M., Benbadis, S., Marsh, E., Joshi, C., Roberts, C., Taylor, A. and Sommerville, K., 2017. Cannabidiol (CBD) significantly reduces drop seizure frequency in Lennox-Gastaut syndrome (LGS): results of a multi-center, randomized, double-blind, placebo controlled trial (GWPCARE4)(S21. 001). French et al (2017). Cannabidiol (CBD) significantly reduces drop seizure frequency in Lennox-Gastaut syndrome (LGS): results of a multi-center, randomized, double-blind, placebo controlled trial. Available at: https://n.neurology.org/content/88/16_Supplement/S21.001.short Accessed on 06/03/2019
  • Hammell, D.C., Zhang, L.P., Ma, F., Abshire, S.M., McIlwrath, S.L., Stinchcomb, A.L. and Westlund, K.N., 2016. Transdermal cannabidiol reduces inflammation and pain‐related behaviours in a rat model of arthritis. European Journal of Pain20(6), pp.936-948.Hammell et al (2015). Transdermal cannabidiol reduces inflammation and pain-related behaviours in a rat model of arthritis. Available at: https://onlinelibrary.wiley.com/doi/abs/10.1002/ejp.818  Accessed on 06/03/2019