Your guide to CBD

Dr Sarah Brewer provides an overview of everything you need to know about CBD

CBD (cannabidiol) is now one of the most popular supplements in the UK as many people find it can help a wide range of common health problems. As a food supplement, CBD can only be promoted to promote general wellbeing which is why labels are unable to provide guidance on what conditions CBD can help. User surveys, however, show that many people take CBD to help relieve stress, anxiety, sleep difficulties, arthritis and other causes of persistent pain.

What is CBD?

CBD is one of over 100 closely related molecules (phytocannabinoids) which are found in cannabis plants. Different strains of cannabis contain different blends of these molecules. Those that contain CBD plus high levels of THC (tetrahydrocannabinol) cause the mind-altering ‘high’ or ‘stoned’ effects associated with marijuana, and these are strictly regulated as a legally controlled drug. Strains of cannabis that have very low levels of THC are known as industrial hemp and these are grown under strictly controlled conditions within the EU for fibre and as a source of CBD.

How does CBD work?

CBD mainly works by interacting with your body’s own endocannabinoid system. This communication network is involved in almost all our physical and emotional responses from mood, relaxation and sleep through to immune reactions and how we perceive pain.

Altogether, researchers have found at least 65 different ways in which CBD interacts with our cells, including our opioid receptors (involved in pain relief) and serotonin receptors (which regulate mood) which may explain why so many people find CBD beneficial for so many different ailments.

How to use CBD safely

The World Health Organization published a report in 2018 which acknowledged the benefits of cannabidiol for common health issues such as anxiety, chronic pain and insomnia.

It also confirmed that CBD is generally well tolerated with a good level of safety and no evidence of recreational use or any associated public health problems.1

We all respond to CBD in different ways and many people only need a small amount to notice benefits. I recommend starting with a low dose (e.g. 5mg to 10mg once or twice a day) and slowly increasing (e.g. to 15mg up to three times a day) to find what works best for you.

The UK Food Standards Agency recommends that you don’t take more than 70mg CBD per day. Higher doses of CBD are more likely to cause side effects of drowsiness and lethargy.

If you have a medical condition always check with your doctor before taking CBD. If you are taking any prescribed medicines it is also important to check for interactions. If your doctor or pharmacist is unable to help, there is an excellent interactions checker at which includes cannabidiol. Do not take CBD during pregnancy or while breastfeeding.

Different ways to take CBD

CBD is usually taken as drops, capsules, gummies or an oral spray. As drops have a strong, earthy taste, you may prefer filter-clear drops which are flavoured with peppermint, orange or lemon, for example. I like CBD in the form of capsules as these have no flavour.

If using CBD drops or sprays, hold the dose under your tongue for a couple of minutes for more rapid results – this allows the CBD to be absorbed straight into your bloodstream.

CBD balms and salves can also be rubbed into painful or inflamed areas to reduce pain perception and to aid healing.

N.B. For those unable to take CBD (for example due to drug interactions or restrictions in elite sport) an alternative substance with similar effects is PEA (palmitoylethanolamide). PEA is derived from palm trees and also interacts with our endocannabinoid system to aid relaxation and reduce pain.2

Current legislation

CBD does not cause a high and is not addictive. In the UK, CBD supplements are therefore legal to take as long as they are produced by licensed suppliers, from approved strains of seed, and do not contain more than 1mg of THC in total per pack. Laws relating to CBD vary widely across the world, however, and even from state to state. It’s therefore important not to travel with CBD without seeking advice about legal status.

What do the different terms mean?

Many different terms are associated with cannabis products which can be confusing. Here’s a quick guide:

  • CBD (cannabidiol) is the most common phytocannabinoid found in hemp strains of cannabis plants.
  • CBD oil is made by combining CBD with an oil (e.g. hemp seed oil, coconut oil or olive oil) to make a supplement.
  • THC (tetrahydrocannabinol) is the phytocannabinoid that accounts for the ‘high’ associated with marijuana strains of the cannabis plant.
  • Hemp or industrial hemp are strains of cannabis plant that do not produce intoxicating effects as they have only low levels of THC.
  • Hemp seed oil is nutritious oil obtained from the seeds of hemp strains of cannabis plants which should not contain significant amounts of either CBD or THC (although contamination can occur during processing).
  • Medical cannabis refers to the use of any cannabis-based extract to relieve a medical condition such as anxiety or pain. This term can include products that are intoxicating (marijuana) or non-intoxicating (CBD) as both are derived from cannabis plants. In practice, however, the term medical cannabis usually refers to medical marijuana.
  • Medical marijuana is the use of the intoxicating herbal drug, marijuana (which may be vapourised and inhaled or taken by mouth) to relieve symptoms caused by medical conditions. Doctors do not recommend smoking marijuana for medical purposes, but it is one way in which marijuana is used recreationally.

Dr Sarah Brewer is the Medical Director of Healthspan and the author of CBD: The Essential Guide to Health and Wellness (Simon & Schuster, May)


1. World Health Organization. ‘Cannabidiol (CBD) Critical Review Report.’
Expert Committee on Drug Dependence. Fortieth Meeting. Geneva, 4-7 June 2018.

2. Ho W-SV et al. ‘Entourage effects of N-palmitoylethanolamide and N-oleoylethanolamide on vasorelaxation to anandamide occur through TRPV1 receptors’,
British Journal of Pharmacology, 155, 6 (2008): 837–846.

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