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The Ultimate Guide to CBD Side Effects
By Anastasia Myronenko

Anastasiia Myronenko

Anastasiia Myronenko is a Medical Physicist actively practicing in one of the leading cancer centers in Kyiv, Ukraine. She received her master’s degree in Medical Physics at Karazin Kharkiv National University and completed Biological Physics internship at GSI Helmholtz Centre for Heavy Ion Research, Germany. Anastasiia Myronenko specializes in radiation therapy and is a fellow of Ukrainian Association of Medical Physicists.

The Ultimate Guide to CBD Side Effects

 alphagreen The Ultimate Guide to CBD Side Effects


If you’re anxious to know how CBD may affect you, you’ve come to the right place. While CBD is repeatedly noted to be well-tolerated in the body with an excellent side effect profile, side effects can happen on occasion. In this article, we will be guiding you through many of the adverse effects that have been recorded in previous clinical trials, and in the absence of research, those that have been speculated and anecdotally reported.
We’ll also be spilling on how you can minimise your chances of encountering these adverse reactions, and who should be avoiding CBD altogether. Before all this, though, we will be reminding you of the basics to do with CBD, how it works and what it does for our wellbeing.


 alphagreen The Ultimate Guide to CBD Side Effects

In recent years, CBD has been at the centre of a wellness frenzy. Clinical study after clinical study – particularly those done since the beginning of the millennium – has attested to the therapeutic benefits and properties of cannabidiol, prompting wellness fanatics all over the world to adopt CBD as a wellness supplement.

Though CBD may be a relatively novel substance, the cannabis plant from which it is derived is not; cannabis (specifically, cannabis Sativa) has been cultivated for thousands of years. The earliest recorded uses of the plant in medicine date back 1400-2000 BC. In the 19th century, William Osler, who was considered to be a “father of modern medicine” actively promoted the medicinal use of cannabis. Osler believed the plant was an effective medicine for treating migraines.

Besides being used for medicinal purposes throughout the ages, cannabis is widely recognised for its recreational uses as well. Within cannabis, there are more than 100 chemical constituents known as “cannabinoids”. Cannabidiol (CBD) is just one example, and is a non-intoxicating cannabinoid. Cannabidiol is frequently confused with tetrahydrocannabinol (THC), another cannabinoid from cannabis. THC, however, is intoxicating and psychoactive, meaning it will make the user “high” when taken in large enough doses. THC is the reason why cannabis is often used recreationally. CBD does not have the psychotropic effect on users that THC has, so cannabidiol won’t get a person high. On the contrary, CBD has even been shown to counteract the activity of tetrahydrocannabinol (THC). Among the wellness-boosting benefits associated with CBD consumption are better sleep, reduced pain, feeling a sense of calm and so much more.

All drugs and vitamin supplements, whether prescribed or over-the-counter, can cause adverse effects. Reactions mainly occur when a person does not use them as recommended. In this article, we will discuss the possible side effects of CBD products. In general, the potential benefits and adverse effects of CBD are incredibly unique to the individual. What works perfectly for one individual may not work for another at all. Everyone is different, so it is advised to check with a doctor before starting to take CBD products daily. Anyone can encounter unwanted symptoms, but we will discuss and focus on how to minimise your chance of this happening.

What CBD is & what it does

Cannabidiol or CBD is a phytocannabinoid that was discovered in 1940. Cannabidiol is a naturally occurring element found in the resinous flower of cannabis. It is a safe and non-addictive substance and refers to one of more than a hundred phytocannabinoids that are unique to cannabis and give the plant its strong therapeutic profile. Every variety of the cannabis family produces CBD, including both hemp and marijuana. While THC and CBD are the most abundant cannabinoids that have received the most attention, there are also many others.

CBD is most commonly found in the form of oil, and can be ingested, inhaled or applied topically. Those are not the only ways to administer this cannabinoid, however. Increasingly, there are various ways to get CBD into your system and multiple formats in which CBD can be found.

 alphagreen The Ultimate Guide to CBD Side Effects

Cannabis acts on the endocannabinoid system, a unique system of endogenous receptors, endocannabinoids and metabolic enzymes that is spread throughout every human’s body. The system plays a mediating role in vital functions and processes like nausea, inflammation, pain, memory, sleep, appetite, immune function, motor control, mood, reproduction and fertility, pleasure and temperature regulation, to name but a few examples. Around our bodies, we have cannabinoid receptors, which come in two types: CB1 and CB2 receptors. These specific receptors are affected when we take cannabinoids like CBD or THC, and it is through our receptors that CBD can exert its effects on us.

The ECS is an essential and complex molecular system which helps to maintain internal systemic balance – a state known as homeostasis. Unfortunately, the ECS can become compromised and change over time. Sometimes, it has trouble maintaining proper balance. Disease and injury can also negatively impact the ECS and, as a result, play a significant role in throwing our bodies off balance. When we take CBD, it purportedly stimulates the ECS. Importantly, CBD does not bind to receptors in the endocannabinoid system as THC does. Instead, it exerts indirect actions on our ECS, in turn bringing about therapeutic effects that hold the potential to bolster our wellbeing.

CBD refinements

In the final stages of the production process to get a CBD product from the hemp plant, the CBD oil will be refined according to what kind of CBD the company wants to sell. A company may decide to keep all of the phytochemicals, compounds and active nutrients that can be found in cannabis. These include terpenes, flavonoids, small amounts of THC and other cannabinoids, and a CBD product of this nature is known as a full-spectrum CBD product.

Alternatively, a company may opt to retain all of these extra elements and only eliminate the THC – this is a broad-spectrum CBD product.

CBD isolate is the third type of CBD refinement. This refers to a product that solely contains cannabidiol, and is the purest variety of CBD on the market, as all other elements are completely removed during the extraction process.

Note that full-spectrum products that contain trace amounts of THC will not make you high, as there is not enough to have this effect. According to UK law and that of many other countries, CBD products must not contain anymore than 0.2% THC.

All the ways to take CBD

 alphagreen The Ultimate Guide to CBD Side Effects

There’s a good chance that if you’re new to the CBD world, you will feel immensely overwhelmed by all the choices available on the CBD market. This choice presents itself in the form of sublingual oils, topicals, edibles and CBD vapes, among other emerging products like suppositories and transdermal patches.

CBD oil and tinctures are the frontrunners as the most popular CBD products. These products typically come in a small glass bottle with a pipette to administer the drops of oil beneath your tongue (sublingually). After dropping some oil under the tongue, it is generally recommended to let the oil sit for 20-60 seconds, and then swallow the remainder. Using a CBD oil in this way should start to produce effects in as quickly as 15-30 minutes after consumption.

With the constant emergence of cannabidiol-infused sweet and savoury goods, CBD edibles are rapidly becoming a favourite way for people to get their daily CBD fix. Whether they are CBD drinks, gummies, mints, chocolate, cookies or any other snack, the infused CBD must be digested before it gets absorbed into the bloodstream. This process can take some time, depending on a person’s metabolism and how much they eat when taking a CBD edible. Sometimes, edibles can take up to 6 hours to be digested and their CBD absorbed, so you may be waiting some time before any effects set in.

CBD-infused topicals (creams, lotions, balms, body butters, salves and oils) are frequently used by those wishing to tackle pain or discomfort in their muscles, joints and skin. Though topical CBD does not reach the bloodstream and only works with local receptors on and under the skin, it is still the recommended delivery method for targeted relief, as it allows you to focus on a specific sore area. As for the effect of topicals, these products can take up to an hour and last up to five hours in total.

For those in search of immediate but short-term relief, inhalation products, such as vape oils to go into your vaporiser, may be the product for you. When CBD is inhaled, it is immediately absorbed through the lungs, and its effect sets in not long after. This method is known as the quickest of all, if a person wants the CBD to reach their bloodstream quickly and feel relief that is more or less instant. That said, a few additional doses may be required when CBD vaping, as its effectiveness has the shortest duration.

Benefits of CBD

CBD is believed to have significant therapeutic potential. Nowadays, many people choose to supplement their regular medication with CBD oil, which can have analgesic, anxiety-relieving, antiemetic, mood-managing effects. Better still, if you take no medication at all, CBD can be turned to as a nature-derived remedy to help you manage symptoms afflicting your body.

Another appealing aspect of CBD use is that it is extremely well-tolerated in the body, with few side effects; it is also non-intoxicating and non-addictive – so there is no risk of becoming hooked on it, as you might with opioids. Let’s take a look at the benefits in greater detail.

CBD & Inflammation

 alphagreen The Ultimate Guide to CBD Side Effects

CBD has been explored for many years as a successful anti-inflammatory agent. There is evidence to suggest that this cannabis-derivative could help us manage inflammatory symptoms affecting us on both our external bodies as well as internally.

By engaging with our CB2 receptors, which modulate immune responses such as inflammation, CBD could potentially soothe inflammatory responses and in turn, relieve the associated pain of inflammation. To put it into the words of Nagarkatti et al. in their 2009 study, cannabinoids can induce apoptosis (cell death) in activated immune cells, suppress cytokines and chemokines at inflammatory sites and upregulate FoxP3+ regulatory T cells – all of which are the pathways by which CBD can regulate and calm inflammation.

CBD & Seizures

Seizures may be caused by illnesses affecting neurological health or by neuronal injury. Fortunately, CBD could offer an effective and efficient way of managing the frequency of seizures, according to multiple pieces of research. Studies published by the Journal of Epilepsy Research in 2017 and by Neurotherapeutics in 2015 have dubbed cannabidiol a worthy anticonvulsant.

CBD is thought to reduce seizure frequency via its interaction with both our CB1 and CB2 receptors, and by interfering with the signalling pathways in the brain. When CBD engages with our CB2 receptors, it may modulate and reduce neuroinflammation. As for our CB1 receptors, CBD can help these control and regulate neuronal activity in the brain. CBD may also help to safeguard our neurons by purportedly blocking any toxins from penetrating and infecting the neurons. High toxin levels are a factor in greater seizure occurrence.

CBD & Skincare

CBD may help clear up your skin. Studies have alleged that CBD can reduce the amount of sebum in the skin. Sebum is produced by the sebaceous glands- too much of it and you will suffer acne breakouts.

As highlighted in research, such as that published in 2014 by the Journal of Clinical Investigation, cannabidiol can regulate the amount of sebum we produce. As we saw above, CBD is anti-inflammatory, meaning it could also help in the battle against inflammatory skin disorders such as psoriasis and eczema. In patients with psoriasis, the proliferation of keratinocytes is the key factor in causing inflammation and raised lesions on the skin that are characteristic of psoriasis. A 2007 study indicated that cannabinoids inhibit keratinocyte proliferation, and therefore support a potential role for cannabinoids in the treatment of psoriasis.

A 2019 study looked into how topical CBD may reduce scarring and marks affecting the skin. The study concluded that topical treatment using CBD-enriched ointment significantly improved the appearance of the skin. What’s more, no irritant or allergic reactions were documented during the period treatment of this study.

CBD & Mental balance

According to statistics presented by Anxiety UK, mental health is in dire straits throughout the UK: in 2013, there were 8.2 million cases of Anxiety disorders in the UK. In 2017, the global figure for those suffering from anxiety was 284 million, and there were estimated to be 264 million people suffering from depression worldwide that same year, says Our World In Data.

On a brighter note, CBD has been highlighted in research to help manage our moods and alleviate feelings of stress and anxiety. It is thought that cannabidiol can work with important mood-balancing neurochemicals in our brain to positively impact our mental state, according to studies such as those done by Blessing et al. in 2015, De Mello Schier et al. in 2014 and Crippa et al. in 2009. In fact, Crippa and his team asserted that CBD could have “a pharmacological profile comparable to that of mood stabilisers”. Studies on animals have reached similar conclusions about the mood-balancing effects of CBD.

As such, many people use CBD to supplement, or even as an alternative to, prescribed medications. A huge bonus of using CBD for these ends is that it possesses fewer side effects and doesn’t lead to a possible dependence.

CBD & Sleep

Improved sleep quality is one of the most apparent benefits of CBD.

By virtue of its work with our neurochemicals, such as adenosine, CBD can enrich the way we sleep and serve as a herbal remedy for insomnia and other sleep-related disorders, such as sleep apnea and Parkinson’s-related REM sleep disorder.

Anxiety may be a leading cause or poor sleep. Studies on CBD’s ability to calm anxiety-induced insomnia, such as a recent one from 2019 by Shannon et al., suggest that CBD is a fantastic pacifier of anxiety, so this cannabis-constituent could indirectly help you sleep by calming your nerves.

Besides cannabidiol, other parts of cannabis are also alleged to aid sleep. One of cannabis’ abundant terpenes, myrcene, seems to have soporific effects, with research testifying that myrcene can enhance muscle relaxation and increase sleep time.

CBD & Nausea

According to the literature, CBD can tackle nausea and vomiting by manipulating the ECS. In 2011, Parker and her team of researchers postulated that  “cannabinoids, including CBD, may be effective clinically for treating both nausea and vomiting produced by chemotherapy or other therapeutic treatments”.

The researchers believed that CBD could actually suppress one’s urge to vomit, and could thus serve as a useful antidote to the emesis experienced by patients receiving chemotherapy. This sentiment has been echoed in multiple studies ever since (Merisades et al., 2017).

Possible side effects of CBD

 alphagreen The Ultimate Guide to CBD Side Effects

For many people, it may seem as though CBD has sprung up out of nowhere. Indeed, within a few years, this cannabis constituent has transformed from being an unknown term to a household name embraced by millions all over the world, who swear by its wellness-enhancing impact.

Though CBD products may be a recent trend, prompting a “green rush”, scientists and researchers have actually been studying cannabidiol since the 1970’s, alongside THC. The World Health Organization (WHO) has even given it their stamp of approval, recently reporting it as safe and useful. Additionally, the FDA’s 2018 approval of Epidiolex (a CBD-based medication for severe forms of epilepsy) and subsequent 2020 approval of this same medication for another rare genetic disorder, says it all.

As we mentioned earlier, cannabidiol is generally well-tolerated, has an excellent side effect profile and does not appear to pose a risk of dependence or abuse. CBD critics are correct when they claim that definitive clinical evidence is lacking, though. While numerous clinical studies and reviews attest to the therapeutic powers of CBD, there are still gaps in research that need to be filled before CBD can be wholly embraced in mainstream medicine.

Currently, the only prescription medications that have cannabis as their foundational ingredient are Epidiolex for epilepsy-related disorders and Nabiximols (Sativex) for MS patients. Nabilone is an anti-emetic and analgesic medication given to either chemotherapy patients to tackle their nausea and vomiting, or to those suffering from severe neuropathic pain. Still, even Nabilone is made of synthetic cannabinoids, designed to mimic the action of THC. These cannabis-based medications were only backed after years of research, trials and mounds of clinical evidence. There is still some way to go before CBD is fully adopted by the medical community, but importantly, there are hundreds of published papers investigating cannabidiol, and they largely point to CBD’s safety and efficacy for a wide variety of symptoms.

Not only are there hundreds of studies investigating the therapeutic potential of this cannabis derivative, but also many dedicated to identifying the possible adverse reactions. There are numerous studies and reviews available which have named such reactions as potential drug-on-drug interactions, diarrhoea, hepatic abnormalities, vomiting, fatigue, and lethargy.

The most comprehensive results available are those from the 2015 research into Epidiolex, the FDA-approved CBD drug prescribed for certain forms of epilepsy. During a series of clinical trials, young people between ages two and eighteen were prescribed high daily doses of CBD for fourteen weeks. Examples of the side effects they endured were tiredness and gastrointestinal problems. Other clinical trials demonstrated that for most people, the side effects were noticed during the first few weeks while they were rapidly raising their dosage. But after lowering the dosage, the adverse reactions seemed to decrease. Aside from these physiological reactions, some healthcare professionals have expressed concerns that exposure to CBD products could serve as a “gateway” to marijuana use.

Adverse effects of CBD are possibly made more likely when it is consumed alongside medication(s). Despite a study conducted in 2011 evidencing that persistently high doses (up to 1,500 mg/day of CBD) are pretty well-tolerated in people, there’s no reason why anyone should test this by taking such high doses on a regular basis. CBD could inhibit hepatic drug metabolism, jeopardise fertility, bring about alterations of in vitro cell viability and decreased activities of p-glycoprotein and other drug transporters. Further studies are required to learn more about in vitro and in vivo side effects.

As you change or up your dose of CBD, keep in mind that the effect it has on you might also change. It is highly advised to keep a close eye on your body’s response when taking CBD.

Specific side effects of CBD products: Oral administration

 alphagreen The Ultimate Guide to CBD Side Effects

Although products made with CBD are becoming more widespread and popular among consumers, there is still a lot of misinformation circulating about this agent of wellness. Thus, it is important to get to know CBD properly so that you can separate fact from fiction.

As we already know, CBD alone is non-intoxicating, and its consumption, no matter how large the dose, will not lead to euphoric sensations as you would have from THC-rich products. As a result, hemp-derived CBD products that comply with the legal requirements of less than 0.2% THC can be considered safe and harmless. The CBD concentration may vary significantly per product. As a result, different formats of CBD may cause different side effects, according to the way they are consumed.

While every person has unique biological makeup, the vast majority of people can ingest CBD oil without feeling any unpleasant side effects.

In rare cases, CBD oil consumers will experience minor symptoms like stomach upset or dry mouth due to decreased saliva secretion, according to the studies we cited above. Minor adverse effects could be the result of numerous factors: there could be impurities adulterating the CBD product, or the dose could be incorrect for that individual.

With regard to doses, every source has something different to say on the matter: some say that up to 200 mg doses of CBD every day are well-tolerated, while Iffland and Grotenhermen claim in their 2017 review that CBD can be consumed in doses of up to 1200-1500 mg daily for up to a month. However, we here at Alphagreen espouse the guideline given by the Food Standards Agency, which tells us to not exceed a daily dose of 70 mg CBD if you are a healthy adult.

Some examples of side effects which may occur when you orally consume CBD include lightheadedness, dry mouth and drowsiness.

Dry Mouth

According to studies, such as one from 2006, dry mouth can occur due to the inhibition of cannabinoid receptors present in the salivary glands. Most works examining adverse reactions cite the presence of THC as a probable cause of dry mouth, and this symptom is often associated with marijuana use.

Drinking plenty of water before and after consuming CBD can help avoid and potentially offset this adverse reaction.


Higher doses of CBD can occasionally induce drowsiness or fatigue. This side effect has been established in studies exploring CBD’s effectiveness in improving sleep, such as the 2019 study by Shannon et al. that we mentioned earlier. While high doses of CBD helped increase the time participants were dormant, some individuals reported increased daytime sleepiness. If you are prone to drowsiness after consuming CBD, experts recommend avoiding CBD before or while driving.


Diarrhoea is another item on the list of potential side effects caused by CBD.

The Epidiolex research we touched on earlier (2015) that was researching the effects of cannabidiol on patients with treatment-resistant epilepsy reported diarrhoea as a side effect of Epidolex, the CBD-based epilepsy drug. Of the 214 participants between the ages of 1 and 30 with severe epilepsy, 19% reportedly experienced diarrhoea. Though this may seem like a huge proportion, it is important to remember that the concentration of CBD and dosage in the study were much higher than the typical concentration found in a commercial CBD product. Participants were receiving 2-5 mg of 99% pure CBD per 1 kg of their body weight per day. Later on, their doses were increased, so they were eventually taking up to 50 mg of CBD per kg of body weight per day.

If you are suffering from diarrhoea after your CBD consumption, it is also possible that some of the product’s ingredients may be causing diarrhoea or contributing to gastrointestinal distress. MCT oil is frequently used as carrier oils in commercial CBD products, and has been known to cause loose stool and diarrhoea in consumers who are not used to taking it. Of course, do not continue to take your CBD product if you are experiencing this reaction, or lower your dose significantly. As always, consult your doctor if you do have concerns.

Specific side effects of CBD Products: Topical administration

Unfortunately, there is not much reliable information out there regarding the potential side effects of topically-applied CBD. This could be taken as a positive, as it is indicative of few reports of adverse reactions when using CBD in this format. However, side effects are by no means an impossibility, so if you do experience an allergic reaction to a CBD topical, do not continue to use it and seek medical attention if necessary.

What will CBD not do?

As we keep saying, research into side effects is continual, so we cannot say for sure what CBD definitely won’t do to you, as everybody is different.

What it should not do (based on previous research), is any of the following:

  • Intoxicate you
  • Slow down your reaction times
  • Affect your memory
  • Cause heart palpitations
  • Cause a lethal overdose
  • Cause hallucinations
  • Turn your eyes red
  • Make you dependent
  • Heighten your blood pressure
  • Affect your kidneys
  • Cause headaches

Who should avoid CBD?

Although CBD has been considered safe by the WHO and other significant health organisations, not enough research has been done to find out if there are any groups for whom CBD products are unsafe. However, some experts suggest that certain groups should avoid taking CBD.

Taking CBD alongside certain medications could pose a health risk. Put simply, CBD may occupy enzymes that the body needs to process drugs such as HIV antivirals, warfarin, antiepileptics and many others – according to leading experts such as Harvard Health. Getting the green light from a medical professional is thus hugely important before self-medicating with CBD, to ensure there will not be any potential interactions with your medication(s).

Due to ethical reasons, testing the safety of CBD in children and pregnant women is extremely rare, meaning there are few studies out there to inform us about its effects and potential dangers. Nevertheless, if we take the testing of Epidiolex as an example, this examined the reactions of children with epilepsy after taking CBD for their condition. The fact that today, Epidiolex is approved as a prescription drug in many parts of the world for children over the age of two speaks for itself. That’s not to say that we should start giving CBD products to children, though, unless absolutely necessary and approved by a doctor.

 alphagreen The Ultimate Guide to CBD Side Effects

Individuals who suffer from liver problems might need to be cautious about their CBD intake. It is currently unclear whether CBD products directly affect the liver or interact with pharmaceuticals associated with liver problems. Monitoring liver enzymes is highly recommended when introducing CBD into your daily routine. Avoiding CBD altogether or sticking to microdoses may be advisable.

According to some studies, CBD can lower blood pressure. Those who experience hypotension, then, might need to monitor their blood pressure when trying new CBD products, and cease their intake if necessary.

For couples who are trying to conceive, it is important to note that the effect CBD has on fertility is not yet entirely known. Some studies claim it may harm your chances of conceiving by affecting your fertility. For instance, a review by Payne et al. posited that cannabis may play a role in “reducing sperm count and concentration, inducing abnormalities in sperm morphology, reducing sperm motility and viability and inhibiting capacitation and fertilising capacity”. In other words, this 2019 study estimates that cannabis use could harm male fertility. So, if you are trying to start a family, it is recommended to avoid using CBD.

A woman who is pregnant or breastfeeding shares everything she consumes with her unborn or newborn baby. Molecules in the mother’s bloodstream can be transferred to the child’s body via breast milk or the placenta. CBD has been detected in breast milk, but it is currently unclear how CBD might affect a developing foetus. In accordance with advice from the FDA, we recommend abstaining from CBD use during pregnancy and nursing, just to be on the safe side.

Some medical professionals worry that CBD intake could harm individuals whose immune systems are impaired, such as HIV sufferers. Equally, there are studies – such as one by the BMJ from 2019 – to suggest that CBD is well-tolerated by and even helpful to HIV sufferers. Most important to remember is not to substitute any prescribed medication(s) or treatments with CBD unless instructed by a medical professional.

Avoiding adverse effects

 alphagreen The Ultimate Guide to CBD Side Effects


Finding the right dose is crucial to minimising the chances of an adverse reaction. Even though CBD is becoming more and more popular throughout Europe and beyond, there are no specific universal instructions or recommendations on how to use it. The reason for this is that finding the right dosage is dependent on so many variables: age, diet, weight, tolerance, CBD concentration, health conditions, the CBD product itself and many more. Moreover, our bodies change over time, meaning doses may not be static, and one that works for you one year may not work so well the next.

Many sources offer rough guidelines on how to identify the appropriate dosage of CBD. Generally speaking, the more a person weighs, the greater the concentration of CBD required. One formula for calculating an initial CBD dosage involves using your body weight as a guide, and gradually increasing your dose. Some recommend taking 1–6 mg of CBD for every 4.5 kg of your body weight. For instance, a daily CBD dose of 15 mg may be beneficial for a 68 kg individual. However, it’s important to remember that this is not a universal rule, and should be taken with caution and used as a very rough guide.

Online CBD dosage calculators may be a useful tool if you’re in need of a helping hand when trying to establish a dosage. Calculators take user-specific factors into account and generate an initial dosage based on what you tell them. A calculator may offer more than one option as a potential dosage, including an initial dosage and further higher doses. Once the desired effects have been achieved, a user can settle on that dose. Just as with the formula we mentioned above, though, online calculators may not give the right answer to absolutely everybody in terms of the optimal CBD dose, so take their recommendations lightly.

A more traditional method would be to keep a journal of your dose and record how your body responds to the CBD, gradually increasing the dose after some weeks and monitoring and writing down your reaction each time.

We get it, finding the right dose seems like a headache; but trust us when we say it is totally worth putting in the work in the short-term, for the benefits that CBD can provide in the long-term!

Speak to a doctor

 alphagreen The Ultimate Guide to CBD Side Effects

As we’ve reiterated throughout this entire read, doctors are a resource that are there to be used, so if you have concerns about a reaction whether a potential reaction or one that has happened already, consulting a doctor is a must.

That said, not all doctors will feel comfortable consulting on CBD use. If this is the case, ask them if one of their colleagues could advise you. The advice of your doctor should be prioritised above your own desires, as they usually know best. This means following their advice if they don’t believe CBD consumption is appropriate in your health circumstances.

Avoid medication clashes

Prescription medications can be affected by CBD. How? CBD inhibits the cytochrome P450 enzyme system. The cytochrome P450 enzymes are found in the liver and are responsible for metabolising toxic substances, as well as most medications. Because CBD slows down the metabolisation of drugs, it may take longer for the body to process certain medications if CBD has been consumed. This leads to a more significant amount of medication being present in the body, and may lead to adverse reactions or overdose.

For patients currently taking prescribed medication(s), including antibiotics, steroids and antidepressants, it is highly recommended to talk to a healthcare professional before using CBD. An adjustment in the dosage of the prescribed medication(s) may be necessary if taking it in conjunction with CBD products.

Select trustworthy brands and products

Not all CBD products and brands are created equal. Thus, when it comes to CBD products, their source and purity matter.

The hemp plant is an excellent hyperaccumulator because it quickly absorbs elements present in the ground where it is grown, even such things as heavy metals and pesticides. The EU has some pretty stringent farming and pesticide laws, meaning many prefer their hemp-derived CBD products to have grown on European soil. Importantly, hemp plants that are grown in fertile soil will produce a final CBD product of the highest quality. The best quality CBD also typically comes from companies that are present throughout the entire manufacturing process of CBD products, from seed to shelf.

Thanks to the huge number of CBD brands pervading the market nowadays, and the unfortunate lack of regulation over CBD marketing, it can be difficult to weed out the dodgy companies from the good ones. Some products may contain ingredients or additives that could pose a danger to your health. Another significant issue is that of labelling: the labelling of CBD products is frequently unclear and inconsistent, making it confusing for people to know what they are buying. Toxicologists Virginia University examined a number of e-liquids that claimed to be 100% natural CBD extracts in their 2017 study. The researchers found one with dextromethorphan, or DXM, which is used in over-the-counter cough medications. This substance is considered addictive when abused. Four of the vape oils being studied contained a synthetic cannabinoid that had the potential to cause psychosis, anxiety and tachycardia. We know this is a little scary – our intention is not to scare you but to give you the reality of what we reputable CBD companies are up against. The more you know, the better-equipped you will be to buy good quality CBD products from reliable brands!

An excellent way to avoid the potential side effects of CBD is to check the seller’s credibility. This can be done by looking for a Certificate of Analysis (COA) for every CBD product you select. A COA is a crucial indicator of a company’s reliability, as it is proof of a third-party lab examination. The document should list the cannabinoid and terpene profile of a product, and should confirm that no heavy metals or harmful toxins have been detected in the product. The THC content should also be stated on a COA (which should be less than 0.2% for UK and many EU products, or less than 0.3% for US products). COAs should be made public by the company, and if they are not, do not hesitate to request one from the company – a brand that has nothing to hide will not hesitate to oblige! Pay close attention to product labelling, and ensure its contents match up to those on the COA.

The importance of reviews is also not to be understated. Checking out trusted review sites will inform you of the quality of the products you’re about to buy and the company from which you’re buying. Look for things like adverse reactions, how the company was to deal with, how they responded when things went wrong and how the products worked or did not work for their customers. Your fellow consumers are your most trusted resource!

The risk of adverse effects increases if you purchase low-quality CBD products from unreputable manufacturers. Products may not have undergone testing, may contain heavy metals, residual pesticides, higher levels of THC, contaminants and/or synthetic cannabinoids. In some scenarios, poor-quality products may not even contain CBD at all. Higher levels of THC can cause side effects like hunger pangs, dry mouth and an altered state of mind.

In summary, buying from reliable and trusted sources is one of the best ways to ensure your CBD is safe, and to minimise your chances of encountering side effects.

Bottom line

Everything we take, herbal or otherwise, carries some risk of side effects, and CBD is no exception to that rule. The good news is that no cases of toxicity from CBD use have thus far been reported, and it doesn’t seem as though any amount of CBD can lead to lethal overdose.

Overall, in the rare instances that adverse reactions do occur, symptoms are generally mild, dose-dependent, and tend to resolve themselves within a few hours.

Research into the potential long-term effects of CBD products is still ongoing; naturally, it takes time to obtain the results of these longitudinal studies that take place over the course of some years. When more research emerges around the potential adverse effects of CBD, we will, of course, update our existing information so that you’re fully up to speed! In the meantime, we hope this extensive guide provides a full and clear picture of all you need to know about the potential adverse effects of CBD.

Anastasiia Myronenko

Verified by a Healthcare Professional

Anastasiia Myronenko

Anastasiia Myronenko is a Medical Physicist actively practicing in one of the leading cancer centers in Kyiv, Ukraine. She received her master’s degree in Medical Physics at Karazin Kharkiv National University and completed Biological Physics internship at GSI Helmholtz Centre for Heavy Ion Research, Germany. Anastasiia Myronenko specializes in radiation therapy and is a fellow of Ukrainian Association of Medical Physicists.


What are the side effects of CBD?

Adverse effects associated with CBD are rare, and CBD is well-tolerated in the body. Some of the previously reported side effects include diarrhoea, dry mouth, lowered blood pressure, nausea, drowsiness, fatigue, lightheadedness, changes in appetite and changes in weight.

Does CBD cause liver problems?

Research into the effects of CBD on the liver is conflicted and unclear. Generally, small daily doses of CBD are unlikely to do any harm to the liver. On the other hand, taking doses that exceed the maximum recommended daily dose (70 mg) chronically are not recommended, in case of causing damage to the liver, among other things.

Studies suggest that those with liver damage should limit the amount of CBD they consume, and consult a doctor’s approval before taking it. CBD may cause the development of high liver enzymes, as in one study. Taking medication(s) alongside CBD poses a health risk as CBD may delay the liver’s metabolisation your medication(s). Contrasting research suggests that CBD may actually improve liver function.

Does CBD cause headaches?

While it is not impossible, headaches are not usually a side effect associated with CBD. Headaches are not typically cited as an adverse reaction in research, but you may hear anecdotal reports of headaches after CBD use. If you feel that CBD is causing you headaches, do not continue to take it, or pause your intake for a few days to verify whether CBD is behind your headaches.

Does CBD affect the kidneys?

There is no evidence to suggest that CBD has any negative effect on kidney function.

Does CBD cause hallucinations?

In studies investigating CBD and neuropsychiatric health, cannabidiol was actually seen to reduce psychotic symptoms and unusual patterns of neural behaviour, such as hallucinations, delusions and others. In short, CBD should not have any effects of this severity on your neurological health. If these effects are taking place, it is possible that you have purchased a product containing illegal amounts of the psychoactive cannabinoid, THC.

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