The complete CBD oil guide

What is CBD?

Over the past decade, the CBD boom has taken over the world. At times, CBD oil has even surpassed vitamin C as the most sold supplement in the UK. Yet, despite making a significant mark in the wellness space and on millions of lives, many people are still left asking: what is CBD? 

CBD stands for cannabidiol – the most abundant cannabinoid (a particular type of molecule) found in the hemp plant, and second most abundant in cannabis (marijuana) after its psychoactive sibling, THC. There are over 140 cannabinoids in the cannabis plant, but CBD and THC are the most commonly known. THC is the one that can get you high, while CBD, on the other hand, can’t. CBD oil is a wellness supplement made using hemp plant (or cannabis sativa L) extract, combined with carrier oil.

CBD oil is not a panacea, but you’d be forgiven for thinking it was, because over the past 60 years, thousands of studies have demonstrated the immense and widespread therapeutic value of this molecule. This is in part down to the unique interaction CBD has with the endocannabinoid system (ECS) – a major physiological system, discovered in the 1990s. Found within every other physiological system and every organ, bone, joint and skin cell, the ECS works to maintain and regain equilibrium in all bodily processes, from sleep, to pain transmission to mood. This system is made up of 2 receptors (called CB1 and CB2) and endocannabinoids (neurotransmitters released on demand to activate the receptors and tell them to bring the body into balance). When our endocannabinoids are depleted or deficient, which can occur due to unhealthy lifestyles, diet, poor sleep etc, they won’t be released properly, and that can result in just about any ailment you can think of. 

When CBD enters the bloodstream, it doesn’t directly activate the ECS, but it attaches to the CB2 receptors (primarily found in the immune system and peripheral organs and tissues including the skin, gastrointestinal tract, liver and bones) and inhibits the enzyme which breaks down our naturally produced endocannabinoids. This results in higher levels of endocannabinoids, which, studies suggest, can help the body restore balance as needed. 

CBD oil products with THC content under 1mg per container that have been regulated by the Food Standards Agency are perfectly legal for use and sale in the UK, and have been since 2016. This is separate from prescription medical cannabis, which is accessed through specialist medical cannabis clinics following an assessment by an appropriate clinician. For a broader view of the prescribed cannabis market, you can also explore our listings of medical cannabis clinics available across the UK. Our rankings are weighted using review volume and aggregate scores from both Trustpilot and Google. Based on this methodology, Releaf currently ranks as the highest-rated and most-reviewed medical cannabis clinic in the UK.

CBD oil products with THC content under 1mg per container that have been regulated by the Food Standards Agency are perfectly legal for use and sale in the UK, and have been since 2016.

Full Spectrum vs Broad Spectrum vs Isolate

When you’re trying to choose the right CBD product for you but you’re unfamiliar with the terminology used to describe the variety of oils available, it can feel like a bit of a minefield. Not only are there the strength and form to take into account, but there’s also the choice between Isolate vs Full Spectrum CBD oil in the UK. What’s the difference, and what would be best for your needs? Here, we break it down for you.

CBD Isolate:

If you see a product labelled ‘CBD Isolate’, this means you’re buying an oil that contains the CBD molecule and no other cannabinoid, suspended in a carrier oil. The THC content must be non-detectable (less than 0.01%). This is a great choice if you’re concerned about having any THC at all in your bloodstream, for example if you’re a professional athlete or work in a job where you might be drug tested. 

Broad Spectrum CBD oil UK:

If a product is labelled ‘Broad Spectrum’, this means it contains a variety of cannabinoids and terpenes but the THC is non-detectable. This is a great balance that offers unique benefits from a range of legal cannabinoids, including CBD, without having to worry about there being any THC present in the oil or your bloodstream after taking it.

Full Spectrum CBD oil UK:

Choosing a ‘Full Spectrum’ CBD oil in the UK means you’re opting for the whole range of cannabinoids extract from the hemp plant, including a trace amount (up to 1mg per container) THC. In the UK, industrial hemp is used to create over the counter CBD oil, and this must legally contain no more than 0.2% THC. The extract used in a full spectrum oil is just how it comes from the plant without any alteration. As well as the full range of cannabinoids from the plant, full spectrum oil also contains flavonoids and terpenes – this offers something called ‘the entourage effect’, whereby all of the cannabinoids and terpenes work in synergy to produce what some researchers believe to be superior benefits.

Full Spectrum vs Broad Spectrum CBD: which is best?

If you’re interested in experiencing the full wellness benefits cannabis has to offer without the psychoactive effects, full spectrum is the best choice. The trace amount of THC present isn’t enough to get you high but, combined with the flavonoids, terpenes and additional cannabinoids, it creates the entourage effect. However, if you’d like the make the most of the plant without THC, Broad Spectrum CBD oil is the best choice for you.

CBD isolate vs Full Spectrum: which is best?

CBD on its own has a lot to offer, and while there are a whole host of other benefits to be gained from other compounds in cannabis, sometimes it’s better to stick with what makes you feel most comfortable. If you have sensitivity to terpenes or concerns regarding THC or other cannabinoids, CBD isolate is the perfect choice. Many of the studies available are looking at CBD isolate too. It’s also a favourite among CBD users who struggle with the earthy flavour of Full Spectrum CBD oils, as CBD isolate products are often mild, flavoured and very palatable. For those who don’t mind the taste or taking trace amounts of THC, Full Spectrum CBD oil is generally considered a more comprehensive and sometimes more effective product, due to the entourage effect.

Benefits of CBD oil

If you’re reading this, you’ve probably already heard of a number of CBD oil benefits, from using CBD for sleep and CBD for anxiety, to taking a regular dose of CBD for pain, or even giving it to your pets! And it’s true – studies conducted over the past few decades do suggest that CBD may have a multitude of potentially beneficial applications worth researching further, thanks to its far-reaching mechanisms via the endocannabinoid system, serotonin receptors, dopamine receptors and vanilloid receptors. The World Health Organisation agrees, with their Critical Review Report stating that CBD has been demonstrated as “an effective treatment of epilepsy in several clinical trials” (particularly in trials for Epidyolex - the only NHS-approved CBD medicine) with additional “preliminary evidence that CBD may be a useful treatment for a number of other medical conditions”.

While the potential benefits of CBD oil have been extensively studied for serious medical conditions such as Epilepsy, use and approval of CBD as an official Medicine is purely reserved for CBD that is prescribed by medical professionals. CBD oil that can be bought over the counter is currently regulated as a food supplement and does not necessarily meet the same rigorous criteria as medical-grade CBD oil.

Over the counter or not, an estimated number of 200 million people use or have tried CBD oil mainly for self-reported stress (65.3%), sleep problems (51.7%), overall improvement in well-being (52.5%), improved mood (44.9%), and anxiety relief (40.9%), with almost 70% saying they have found CBD to be effective. But let’s take a look at how the science supports that.

CBD for Sleep & Anxiety

Cannabis as a whole has been used for stress management and as a sleep remedy for many thousands of years, supporting calm and somnolence through THC boosting high levels of Anandamide (the ‘bliss molecule’ endocannabinoid), sleepy terpenes such as myrcene, minor cannabinoid CBN (cannabinol) and of course CBD. 

When it comes to using CBD for sleep and CBD for anxiety, two of the key mechanisms involved are the activation of serotonin receptors, and the increase of Anandamide levels in the brain (through the CBD molecules action of inhibiting the enzyme that ordinarily breaks this down in the body). This endocannabinoid acts as a gatekeeper for stress, preventing the cascade of chemicals that create the ‘fight or flight’ response, unless absolutely necessary. Low levels of this endocannabinoid can result in higher anxiety, and poor sleep. Higher levels tend to see improvements in both.

One thing that’s really interesting about CBD (and well worth noting if you plan of using it for sleep) is that it’s biphasic - while one dose might be sedating, another could be stimulating. However, it’s worth considering the underlying cause for sleep issues, as many studies suggest that CBD might serve as a helpful sleep aid due to its suggested anti-anxiety properties, which research has shown occur at lower doses (15 – 50mg) for general anxiety management and higher doses (300 – 600mg) for diagnosed anxiety disorders and recall-triggered anxiety symptoms.

One study monitoring 72 patients over three months, using capsules containing 25mg – 75mg, found anxiety scores decreased within the first month in 57 patients (79.2%) and remained decreased during the study duration. Sleep scores improved within the first month in 48 patients (66.7%) but fluctuated over time. 

Studies exploring using CBD for insomnia have found the best results from high doses of CBD (150-600mg) and other studies have noted sedative effects from taking CBD at similarly high doses. 

But the benefit of CBD oil is not a one-size-fits-all, which is perhaps why so many studies call for further research before jumping to conclusions. Some even find CBD to have no effect on sleep at all. It’s possible that you may experience better results on sleep and anxiety by using a whole plant or raw CBD oil product containing CBDa (the raw precursor to CBD), which has a significantly stronger effect on serotonin receptors (serotonin plays a well-established role in sleep and mood). This is a perfect example of why it can a good idea to access a CBD prescription and receive medical guidance on dosage when treating an actual condition, rather than just using CBD oil as a wellness supplement.

CBD for Pain and Inflammation

As well as the activation of the endocannabinoid system helping the body to regain balance when experiencing pain and inflammation, here we must also look at CBD’s action on serotonin and vanilloid receptors. An animal study exploring CBD’s impact on the latter found that CBD may have a de-sensitizing effect on vanilloid receptors at a low dose, which research suggests can inhibit pain signaling. 

As one of the most studied neurotransmitters related to pain regulation, serotonin receptors are targeted by many activities and are recommended and prescribed for chronic pain and inflammatory conditions. Studies evaluating the relationship between serotonin and disorders such as irritable bowel syndrome, fibromyalgia, migraine, and other types of headaches also suggest a clear impact of this neurotransmitter, which CBD (and CBDa) activates.

Although more research is needed to get a clearer picture of how CBD may or may not help with chronic pain and inflammation, some research certainly suggests a positive outlook. A 94-week observational study with 97 participants prescribed opioid medication for chronic pain found that, after using a daily dose of CBD hemp extract over 94 weeks, 50 out of 94 (53.2%) had decreased their opioid medications by week 8. The secondary outcome reported in this study was that 94% of participants improved quality of life as measured by pain and sleep-related open-ended questions.

Side Effects & Safety

Before taking CBD it’s important to educate yourself on possible CBD oil side effects. Fortunately, they tend to be few and far between but there are some risks to be aware of.

As well as having its therapeutic potential supported by WHO, their 2017 Critical Review Report also states that CBD is “well tolerated with a good safety profile” and has “no effects indicative of abuse or dependence potential”. But, while safe, there are a handful of common CBD oil side effects worth knowing about. There are also some potentially quite serious drug interactions that make CBD less suitable for people taking certain medications, including blood thinners (such as Warfarin), antidepressants (particularly the sedative sort, like Valium or Xanax) and seizure medications (including clobazam, lamotrigine, and valproate). If adverse effects occur, stop taking the oil until symptoms subside, lower your dose or contact your doctor if concerned.

Most people take CBD oil with no side effects at all, however if any are experienced, they usually include dry mouth, drowsiness, reduced appetite and diarrhoea. One study noted more severe side effects in animals, including developmental toxicity, embryo-fetal mortality, central nervous system inhibition and neurotoxicity, hepatocellular injuries, spermatogenesis reduction, organ weight alterations, male reproductive system alterations, and hypotension, although at doses higher than recommended for human pharmacotherapies. These are not frequently noted in other studies and have not been flagged by WHO in their Critical Review Report. 

Drug interactions can present a problem as CBD can affect how medications are metabolised. CBD inhibits certain liver enzymes in the CYP450 enzyme system – particularly CYP3A4 and CYP2D6. These enzymes break down a high percentage of all prescribed drugs, and this interaction could potentially result in a build-up of those drugs to toxic levels if you continue to take them alongside CBD oil. Older adults are at greater risk still, due to age-related physiological changes and a higher tendency to take multiple medications. Dose, method of use, age, weight and purity of product all also play a part in safety and efficacy.

It’s vitally important to recognise that just because CBD is a natural supplement, it can still have a strong impact on the body, whether prescribed as a medicine or bought over the counter as a novel food supplement. 

It’s always best to consult a doctor before taking CBD if you have any concerns, possible underlying conditions or if you’re taking any medication. It is generally not advised to take CBD oil while pregnant or breastfeeding due to lack of research in these areas.

How to take CBD oil

Learning how to take CBD oil is easy! Although it does vary depending on the type of CBD product you choose. Capsules, you swallow; gummies, you chew; vapes, you inhale; patches, you apply. But with sublingual drops (the classic and most popular form of CBD oil), there are some simple tips you should follow to get the most out of your supplement. 

The benefit of using CBD oil sublingual drops is that this method allows the CBD oil to absorb quickly and effectively, directly into your bloodstream in a matter of minutes. It bypasses the lengthy digestive process, offers excellent bioavailability (the amount of the active ingredients that actually get to work in your body), has a fast onset and remains active for a few hours.

Here’s how to take CBD oil (sublingual method step-by-step):

• Place the desired number of drops under your tongue.

• Do not immediately swallow.

• Hold the oil under your tongue for 1-2 minutes. This allows the oil to absorb directly into your bloodstream via your sublingual gland.

• Swallow the remaining oil.

• For further enhanced absorption, take your CBD oil right after brushing your teeth. Studies suggest brushing your teeth can help clean away any additional barriers and boosts blood flow to your mouth, potentially increasing the rate of absorption when an oil is absorbed via the sublingual gland.

CBD Dosage

Most CBD products are clearly labelled with the dose per drop and/or per 1 millilitre (ml), as well as the total milligram (mg) dose in the bottle. If it’s not listed, you can calculate the dose per 1ml by dividing the total mg of CBD by the bottle’s size in ml. 

For example:

A 1000mg CBD oil in a 10ml bottle would contain 100mg per 1ml. 

To find the dose per drop, divide the resulting number by 20 (the estimated number of drops in a bottle).

But what’s your CBD dosage? 

The Food Standards Agency currently advises healthy adults to consume no more than 10mg of CBD oil per day. However, almost all clinical trials researching the potential therapeutic use of CBD oil use considerably higher doses than this (in fact, CBD oil has been tested safely with no serious adverse effects up to 6000mg in a single dose). Some CBD products, such as capsules, also contain more than 10mg in a single dose. Really, CBD dosage is often quite individual and can be affected by a number of factors, including body weight and existing endocannabinoid level and function. 

When buying a product, a 500mg oil is generally considered a good low starting product, 1000mg is medium strength, and anything over that is strong. 

Start low and go slow

To find the best CBD dosage for you it’s a good idea to start low and go slow. Begin with the lowest recommended dose and increase gradually, adding a drop or two each time you take the oil, every week or two.

It can be helpful to keep a journal of your progress, noting the CBD dosage you’re using and tracking how you feel every day. This will allow you to spot if/when any noticeable changes occur and if/when things plateau, so you can avoid taking more than you need to. 

How long does CBD oil take to work?

Technically, CBD oil has an immediate effect and becomes active in the body via sublingual drops in 15-30 minutes, edibles in 30-90 minutes, topicals in 15-45 minutes and vapes in 1-3 minutes. But the cumulative benefits take longer. It can take several days or even weeks for endocannabinoids and CBD to build up in your body before you start to see results. 

If you’d like to keep a steady flow of active CBD in your bloodstream during this time, you’ll need to top up throughout the day. Sublingual oil remains active for around 3 hours, CBD vapes for approximately 1-2 hours, CBD capsules for roughly 4-6 hours. Some CBD patches offer slow release over 24-48 hours. However, CBD can remain in the body for days (albeit, inactive) after taking and it varies from person to person.

Try taking the oil consistently for at least a month (and regularly throughout the day, the number of times depending on the type of CBD product you use and its active duration) before you decide whether or not CBD oil is working for you.

For a more interactive guide, use our CBD dosage calculator below as a guideline.

CBD and Medical Cannabis – What’s the Difference?

Although CBD is usually in medical cannabis products, they are not the same thing. It is only possible to buy food grade CBD oil over the counter without a prescription, whereas you must have a prescription to gain access to medical cannabis in the uk (or medical grade CBD oil) which has been legal in the UK since 2018. 

Obtaining a medical cannabis prescription is very straightforward, legal and safe with a reputable clinic. When you’re prescribed medical cannabis, you’ll be assisted on dosage and appropriate use by a medical consultant. Three licensed medical cannabis products (Epidyolex, Sativex and Nabilone) are also available on the NHS – access to a prescription for these can be initiated by a specialist hospital doctor for severe epilepsy, multiple sclerosis-related muscle spasticity, and chemotherapy-induced nausea (when other conventional treatments have failed).

CBD is just one of over 140 cannabinoids in the cannabis plant. While broad and full spectrum over the counter CBD oil can contain some other cannabinoids, more can be included in prescribed medical cannabis. These include controlled cannabinoids, such as THC and CBN. 

All over the counter CBD oil in the UK must, by law, be derived from hemp stalks and leaves, which are traditionally used for making clothing, paper and industrial products, rather than medicine. This plant naturally contains trace amounts of THC (and in the UK must legally must contain no more than 0.2% THC). Medical cannabis products, on the other hand, are derived from cannabis (marijuana) flower, which results in a more potent oil and the presence of THC. Cannabis flower is also available on prescription to vaporise, but it is illegal to smoke medical cannabis. It also remains illegal to use and possess in cannabis in the UK without a prescription, even if it is used for medicinal purposes. 

CBD oil and medical cannabis are also regulated by totally different bodies (the Food Standards Agency, for OTC CBD, and The Medicines and Healthcare products Regulatory Agency (MHRA) for medical cannabis), and therefore adhere to different regulatory criteria. 

Over-the-counter CBD oil products will likely be enough for most people looking for a general wellness boost. You can choose between isolate (CBD only), broad spectrum, full spectrum and even raw whole plant products which contain a range of cannabinoids and terpenes, with up to 0.2% THC. However, you might consider opting for a medical cannabis prescription if you have a more serious medical need to be met. If you have a condition that has been diagnosed and has led you to try other medications or therapies, from anxiety disorder and insomnia to chronic pain and gastrointestinal conditions, you could be a good candidate for medical cannabis.