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CBD (Cannabidiol) Benefits, Side Effects & Safety Information

Published: 13th May 2018. Last updated: 21th July 2019.

Shaun Ward MSc ANutr

Editor & Fact Checker


CBD, also known as Cannabidiol, is one of hundreds of cannabinoids found in the cannabis plant.

Cannabinoids are molecules that bind to cannabinoid receptors in the body and signal for a biological effect to occur.

CBD is the second most abundant cannabinoid found in Cannabis after tetrahydrocannabinol (THC), a compound that is responsible for giving cannabis its psychoactive effects.

Due to this, THC is responsible for the euphoric and mind-altering effects of cannabis whereas CBD lacks this psychoactive component, despite both effecting central nervous system activity.

In other words, CBD is an extracted constituent of cannabis that should not be categorized in the same light as marijuana or ‘weed’. User data clarifies this distinction, with CBD being most frequently used as a specific therapy for medical conditions rather than for recreational use.

CBD has gained much support from preclinical trials – stage of research before human clinical trials - with a supposed therapeutic efficacy against a diverse assortment of medical conditions including anxiety, depression, seizure disorders, psychotic symptoms, inflammation, neurodegeneration, and chronic pain.

Some evidence in animal studies also provides some interest to potential disease-treating properties for cardiovascular disease, cancer, and multiple sclerosis.

Although preclinical results look promising, it is clear human research is necessary to progress our knowledge of the drug and to identify the clear mechanistic benefits of CBD.

The Potential Benefits of CBD

Below we've listed every potential benefit we've found with credible scientific backing:

It May Help To Improve Anxiety

Although anxiety is a natural response to our perceptions of threatening situations, excessive anxiety can lead to maladaptive tendencies.

Excessive anxiety is a symptom of a number of neuropsychiatric disorders, including social anxiety disorder, panic disorder, post-traumatic stress disorder, and obsessive-compulsive disorder.

Further, despite not being causal factors, anxiety-related disorders have been associated with a highly diminished sense of well-being, elevated rates of unemployment, relationship breakdowns, and even an elevated suicide risk.

CBD’s most popular benefit is its anxiolytic action; relief of anxiety.

CBD activates cannabinoid receptors and signals a negative feedback of the neuroendocrine stress response, protecting against the adverse effects of chronic stress [1].

Interestingly, CBD has a low binding rate to cannabinoid receptors compared to THC, however it may also function as an indirect activator of receptors, potentially via alteration of the receptors fundamental activity [2].

It is also possible that CBD acts as a modulator to the signaling mechanisms of cannabinoid receptors which underly its anxiolytic effects.

The effect of CBD in animals has been confirmed with well-designed, validated anxiety tests; the elevated plus maze test, the Vogel-conflict test, and the elevated T-maze test. For all these tests, it seems the anxiolytic effects of CBD present a bell-shaped dose-response curve, with improvements in anxiety at moderate but not higher doses.

To add to this, prior stress also appears to influence the extent of CBD’s effects, with stress-promoting effects (anxiogenic) in non-stressed animals but anxiolytic effects in stressed animals. This may indicate that CBD is a beneficial treatment for stress, but is not necessarily effective at preventing its onset.

Findings from neuroimaging studies that assess brain activity and responsiveness also convey that CBD may have certain ‘neurobiological targets’ in the brain for its action [3]. These include the reduction and altered connectivity of neurons in the brains medial temporal lobe; responsible for the processing of emotions. However, current findings are limited by small sample sizes and a lack of independent replication.

It May Help To Reduce Pain

One of the main reasons why individuals take CBD is to relieve pain.

Although the mechanisms for CBD’s involvement in pain relief are unclear, it does seem to have an effect on reducing pain sensitivity.

CBD reduces pain due to its anti-inflammatory and anti-oxidant properties, as well as its interaction with cannabinoid receptors, specifically in the spinal cord.

CBD has shown in preclinical trials to either directly or indirectly potentiate the cannabinoid receptors that are associated with anti-inflammatory activity, which theoretically make it suitable for pain relief treatment [4].

CBD also inhibits the degradation of endocannabinoids (neurotransmitters that bind to cannabinoid receptors), thus increasing endocannabinoid levels and leading to opioid-sparing effects in preclinical models of pain. This is due to the endocannabinoid system directly interacting at many points with the bodies major pain control systems.

Amazingly, in animal models’ cannabinoids have proved to be 10 times more potent than morphine in effecting the neurons that mediate pain.

At least in animals, CBD significantly suppresses chronic inflammatory and neuropathic pain without causing any apparent tolerances over time [5].

Humans that have experimented with CBD also commonly report one of its main benefits to be pain relief, although this evidence is only subjective.

CBD may in future be a novel therapeutic strategy for pain relief, considering nearly all prescription drugs for the treatment of chronic pain currently come along with many unpleasant side effects; indigestion, blood clots, and kidney damage.

It May Have An Anti-Cancer Effect

CBD has an arguable influence on the growth, or inhibition of growth, on various cancer cells.

On the one hand, studies find an upregulated expression of cannabinoid receptors and elevated levels of endocannabinoids in a variety of cancer cells; namely skin, prostate, and colon cancer [6]. To add to this, the concentration of endocannabinoids and the expression of their receptors has been frequently stated in cancer research to be associated with the “aggressiveness” of cancer.

On the other hand, there are other reports indicating that an activation of the cannabinoid receptors can impair cancer development and hence signaling from cannabinoids can be deemed to inhibit tumor growth [7]. In the same manner, an increased level of endocannabinoids has shown to cause a reduction in tumor growth rate in some preclinical trials [8]. Limited research has also demonstrated that endocannabinoids can work to stop the growth of prostate cancer cells in a dose-dependent fashion.

Clearly, the current research cannot define CBD as having pro- or anti-cancer properties.

CBD’s protumorigenic or antitumorigenic effects seem to be largely circumstantial, with both being possible given the right biological environment.

Human clinical research is essential to clarify the relationship between CBD and cancer.

The Legality of CBD

The worldwide regulatory and legality status of CBD is complex and constantly changing, and people are advised to check for eligibility in their resident country before purchase or use.

Recently, grants in many countries are currently being approved by the Food and Drug Administrations for prescription use for conditions such as pediatric seizure disorders.

However, for recreational use the laws are very complex and largely depend on the strength of the CBD and its origin – with hemp-derived CBD being approved more than marijuana-derived CBD as it comes attached with a much lesser amount of THC (0.3% vs 30% THC).

Currently, hemp-derived CBD is legal in most countries, but marijuana-derived CBD is not legal in most countries because the growth and cultivation of marijuana is not legal.

How Much CBD Should You Use?

As the acceptance and use of CBD as a therapeutic substance is in its infancy and human trials need to be conducted in the future, there is currently no recommended daily amount or universal dose. With multiples variables (weight, metabolism, genetics, product consistency) to consider it is also not possible to predict a universally accepted dosage.

Based on user reviews and the current information about CBD, the most common serving size seems to be 25mg, taken twice daily - 50mg total.

It is suggested to increase the amount of CBD by 25mg every month if there are no noticeable results or side effects. Similarly, doses should be reduced by 25mg if side effects occur.

In any case, users should start with the minimal suggested CBD dosage on any product, then gradually increase the dose until they achieve the desired results.

However, it is also important to consider the route of administration of CBD when determining the best possible dosage as bioavailability can be affected. CBD can be taken via many different routes; ingestible, smokable, and topical solutions.

Ingesting CBD will take longer to notice the effects as it has to be processed by the digestive system and the liver, potentially reducing the amount of active CBD available for your body to use. On the other hand, products applied under the tongue or inhaled are more efficiently and quickly absorbed directly through the mouth and into the blood stream where they are immediately available.

What Are The Different Forms of CBD?

There are 3 main forms of CBD:

  • CBD Oil – This is probably the most popular form of CBD and can be found in capsule and edible products. It is also available in topical products such as balms and lotions.
  • CBD Wax - Wax is a highly concentrated form of CBD, made by treating the extract so that it solidifies and crystallizes. CBD wax is very potent and should be used with caution due to the high concentration.
  • CBD Isolate – This is the most pure and natural form of CBD, as the processing of CBD isolate removes the chances of contaminants or other chemicals. It is as near to 100% pure CBD as you can get, making it easy to measure dosages.

How to Take CBD?

There are 3 main ways to take CBD:

  • CBD “drops” - A common form of CBD, and usually come with a “suggested serving size” and total milligrams of CBD listed on the packaging. This makes it simple to determine the amount of CBD you would like to ingest. To consume, place the correct amount of ‘drops’ under the tongue, using a dropper, and leave the CBD oil under the tongue for at least 60 seconds. This allows for better absorption via the blood vessels underneath your tongue – efficiently bypassing first-pass metabolism.
  • CBD E-Liquid/Vape Cartridges - Vaping and inhalation is the fastest way to deliver CBD and provide an immediate response. To use simply inhale through the mouthpiece slowly for ~3 seconds. Fill the lungs with an additional breath and hold for a few seconds. Exhale when ready. There are pre-filled vapes available for purchase that are generally cheap, or more expensive vaporizers that can be re-filled with CBD e-liquid.
  • CBD Edibles – This process is as easy as it sounds. Eat! Edibles are better for those seeking sustained effects, or for those who want to control their usage, as there is typically a delayed onset until one notices the effects.

Side Effects and Safety Information

Overall, studies have demonstrated no common adverse effects with CBD [9].

It is noted that there have been reports of infrequent, yet notable, reported side effects of dry mouth, fatigue, diarrhea and decreased satiety following CBD use.

From preclinical studies and reported human use, CBD in physiologically normal amounts is generally safe, but side effects may appear with excessive doses, or by interactions with prescription medications.

These questions reinforce the need for long-term CBD research that may clarify any potential unanticipated side effects.

It is also very important for users to realize that CBD products are largely unregulated, and there is no detectable way for users to know the quantity of CBD, or other constituents, which may be present in the products they purchase.

If you're considering taking CBD, check with your doctor first - especially if you have any health conditions.

CBD has not been linked to any deaths. It does not seem as though it is possible to overdose on CBD, although extremely high doses have not been tested in humans.

Also, CBD does not cause intoxication like THC, or alcohol and opioids, so it is unlikely to be responsible for indirect deaths and fatal decisions.


CBD is an active cannabinoid found in the cannabis plant.

CBD acts on cannabinoid receptors to improve anxiety, depression, seizure disorders, psychotic symptoms, inflammation, neurodegeneration, and chronic pain.

CBD has no common side effects and generally appears to be safe. It is recommended to take 25-50mg per day, split into two dosages.

The most popular way to take CBD is by placing CBD “drops” under the tongue.

The legality of CBD is largely dependent on the country, although hemp-derived CBD is legal in most countries.

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