What does CBD oil do? Effects and what the evidence shows

CBD (cannabidiol) acts on several signalling systems in the body, including the endocannabinoid system, without causing a high. The strongest evidence is for a prescription CBD medicine in three rare forms of epilepsy. Research on anxiety, sleep, skin and joint comfort is still developing. CBD is generally well tolerated, but it can interact with some medicines.

What does CBD do in the body?

CBD is one of the main cannabinoids in hemp. Unlike THC, it does not act directly on the CB1 receptors in the brain that cause a high, and it binds only weakly to CB2 receptors. Instead it works on a range of targets at once. The WHO's 2018 review lists the serotonin 5-HT1A receptor, adenosine and glycine signalling, and the GPR55 receptor among them (WHO, 2018).

CBD also acts on the endocannabinoid system indirectly. It slows the breakdown of anandamide, one of the body's own cannabinoids. In a clinical trial, blood levels of anandamide rose with CBD (Leweke et al., 2012). The endocannabinoid system is a signalling network involved in nerve signalling, pain perception and gut, heart and liver function (Izzo et al., 2009). Our guide to the endocannabinoid system explains how it works.

Because CBD touches so many targets, it is studied for many different uses, and researchers are still working out which mechanism explains which effect. The next sections separate what has been shown in people from what is still being researched.

Why do people use CBD oil?

Surveys ask users directly. In a 2021 study of 387 CBD users, three quarters of them in the UK, the most common reasons were anxiety, sleep problems, stress and general well-being. Most respondents used less than 50 mg a day, and 14% applied CBD to the skin (Moltke and Hindocha, 2021).

Surveys show what people are looking for, not what CBD has been proven to do. For that, you need controlled trials, which is what the table below summarises.

What does the research show? Evidence by topic

We graded each topic by the best type of study available in people. Strong means large placebo-controlled trials or a regulatory approval. Moderate means several small controlled trials pointing the same way. Early means research is still developing: lab work, animal studies, or small or first trials.

Strong: epilepsy, tolerability and no high

Epidyolex is a prescription CBD medicine. The EMA has approved it as an add-on treatment for seizures in Lennox-Gastaut syndrome and Dravet syndrome (together with clobazam) and in tuberous sclerosis complex, from the age of two (EMA). In a trial of 120 children and young adults with Dravet syndrome, monthly convulsive seizures fell from a median of 12.4 to 5.9 with CBD, against 14.9 to 14.1 with placebo (Devinsky et al., 2017). A trial of 225 people with Lennox-Gastaut syndrome found similar results (Devinsky et al., 2018). These trials used 10–20 mg of CBD per kg of body weight a day, taken by mouth under a specialist's care. Epidyolex is the only medicine made of CBD alone that is approved in the EU; consumer CBD products, including ours, are not medicines.

On safety, a review of 12 placebo-controlled trials concluded that CBD "is well tolerated and has relatively few serious adverse effects", while interactions with other medicines should be monitored (Chesney et al., 2020). The WHO's Expert Committee on Drug Dependence reached a similar view in 2018: CBD is generally well tolerated with a good safety profile and shows no effects indicating abuse or dependence potential in humans (WHO, 2018).

Moderate: anxiety in stressful situations

In a double-blind trial, 24 people with social anxiety took a single 600 mg dose of CBD or a placebo by mouth before a simulated public-speaking test. The CBD group reported significantly less anxiety and discomfort, and their responses came close to those of people without social anxiety (Bergamaschi et al., 2011). A review of human and animal studies concluded that CBD has considerable potential for anxiety, but that most human studies used single doses and longer trials are needed (Blessing et al., 2015). Our guide to CBD for anxiety and stress covers these studies in more detail.

Early: sleep, skin and joints

• Sleep. A systematic review of cannabinoid sleep studies found improvements in 7 of 19 randomised trials, most often in self-rated sleep quality and in people with pain-related conditions (Velzeboer et al., 2022). Formula Swiss is involved in a University of Groningen study of CBD and CBN for sleep. See our guide to CBD oil and sleep.
• Skin. In human skin cells and skin samples, CBD reduced oil production and signs of inflammation (Oláh et al., 2014). In patch tests on healthy volunteers, topical CBD products caused no irritation or sensitisation (Maghfour et al., 2021).
• Joints, with CBD on the skin. In a small crossover trial, 18 people with thumb arthritis used a CBD cream or the same cream without CBD for two weeks each. Pain and hand-function scores improved more with CBD, and no side effects were reported (Heineman et al., 2022). In rats, a CBD gel on the skin reduced joint swelling and pain behaviour (Hammell et al., 2016).
• Pets. Research in dogs and cats is growing quickly. Our guides to CBD for dogs and CBD for cats go through the studies.

A review of 35 studies of CBD in patients found improvements in 23, across doses from under 1 to 50 mg per kg a day. The authors called for larger trials to pin down effective amounts for each use (Millar et al., 2019).

What are the common myths about CBD?

• "CBD gets you high." It doesn't. That is THC's effect, through the CB1 receptor. Our guide to CBD vs THC explains the difference.
• "CBD cures everything." Only one medicine made of CBD alone, Epidyolex, is approved in the EU, and only for specific epilepsies. No consumer CBD product is approved to treat, cure or prevent a disease.
• "More is always better." In trials, side effects such as sleepiness and diarrhoea became more frequent as the dose went up (EMA). Follow the label of your product.
• "Natural means it can't interact with anything." CBD is broken down by the same liver enzymes as many medicines and can change their levels. See CBD and medication interactions.
• "CBD is addictive." The WHO found no signs of abuse or dependence potential in humans (WHO, 2018).

How does CBD feel? Does it get you high?

CBD does not cause a high, euphoria or altered perception. In a placebo-controlled trial in Maastricht, 26 people drove 100 km on public roads after vaporising different types of cannabis. CBD-dominant cannabis did not affect driving, while THC-dominant cannabis did (Arkell et al., 2020).

The WHO review describes a placebo-controlled trial in which 600 mg of CBD by mouth felt no different from placebo on scales of intoxication and mood, while 10 mg of THC caused intoxication and euphoria (WHO, 2018). The most common side effect of CBD in trials was sleepiness, especially at high doses, so don't drive if CBD makes you drowsy. If you are drug-tested, read our guide to CBD, drug tests and driving.

How long do the effects of CBD last?

That depends on how CBD enters the body. In human studies, mostly with CBD taken by mouth or as a mouth spray, blood levels peaked within 0–4 hours (Millar et al., 2018). With twice-daily use for a week, it took 56–61 hours for the level in the blood to halve (EMA).

For CBD applied to the skin, fewer data exist. The cream trial above measured its results after two weeks of use twice a day. Our CBD oil dosage guide shows how much CBD is in one drop of each of our oils.

Is CBD safe? Side effects and who should avoid it

CBD is generally well tolerated. In clinical trials the most common side effects were sleepiness, diarrhoea, reduced appetite and tiredness, mostly at prescription doses. At high doses CBD can raise liver enzymes (EMA). Our guide to CBD side effects covers the figures.

How does Formula Swiss approach CBD's effects?

Our human oils and creams are notified as cosmetics for use on the skin (CPNP in the EU, SCPN in the UK). They are not medicines, so we don't promise health effects. We describe what the research shows instead, including where it is still developing. Every production batch is tested, and we publish the certificates of analysis.

We also support the science. Formula Swiss has been a co-founder and shareholder of the EIHA Novel Food Consortium since day one in 2019. The consortium is gathering the safety data that EU and UK regulators require before CBD can be authorised as a food. We funded University of Bologna research that mapped cannabinoid receptors in the gut and mouth of cats (Stanzani et al., 2020; Polidoro et al., 2021). For a broader introduction to what CBD oil is and how it is made, see What is CBD oil?

Our CBD oils, with every batch's certificate of analysis: browse the CBD oil range.