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Can CBD cause side effects — if so, which ones?

Focus on Ingredients 17.11.21 5 min. read

The list of possible benefits to taking CBD is long: Initial studies suggest possible applications in multiple areas, from epilepsy to pain and perhaps anxiety as well.


This leads other relevant questions to arise: Does CBD have side effects? Is CBD known to interact with medications? Is CBD safe for pregnant women and nursing mothers? (Hint: Yes, yes and no.)


What the WHO says about CBD


In a 2017 report, the World Health Organization (WHO) stated that ‘CBD is generally well tolerated with a good safety profile’ based on a number of open and controlled studies [1]. They also mentioned that:

  • ‘CBD has been found to have a relatively low toxicity.’
  • ‘CBD alone produces no significant psychoactive, cardiovascular or other
  • effects.‘
  • ‘CBD does not produce the adverse effects typically seen with THC.’
  • ‘Controlled, human studies regarding the potential physical dependence effects (e.g. withdrawal and tolerance) of cannabidiol have not been reported.’

It’s a matter of application


The onset of potential side effects obviously depends on the kind of product we use, how we use it and how much of it we use.


Hemp seed oil, which is sometimes mistaken for CBD oil, usually contains negligible amounts of CBD or no CBD at all. Unless an extract or isolate of CBD (or of another cannabinoid) has been expressly added to it, hemp seed oil is simply a food supplement that is used much like other oils such as sunflower seed, sesame and peanut oil.


CBD oil that contains significant amounts of cannabidiol can be ingested orally via drops or a spray, or infused into other edible products such as chocolate and gummies. These types of products can bring about some known side effects, which are mentioned in the next section.


Inhaled CBD takes many forms and can also present side effects. In some regions, CBD is available in liquid cartridges that can be inserted into vape pens. However, not all liquid cartridges and vape pens are safe for use. CBD is also available in dry flower from that can be vaporised in safe machines that are registered medical devices. Those who smoke CBD dry flower in cigarettes or ‘joints’ face the risk of developing serious lung diseases, including cancer, as the resulting combustion is very harmful, just like with other tobacco products.


CBD is also available in CBD creams. At this time, there have been no reports of adverse side effects, apart from occasional contact allergies to the cannabis plant.


CBD side effects, from A to Z


Allergic reactions

Some people are allergic to the pollen of the cannabis plant. However, this is typically a minor issue because female plants are used almost exclusively in the manufacture of cannabis products such as CBD oil, and female plants don’t produce pollen.


Increased intraocular pressure

Results from a study on mice show that CBD can increase intraocular pressure in the eyes [2]. While the mechanisms behind this phenomenon are still unclear, those who already suffer from increased intraocular pressure and conditions like glaucoma, should exhibit caution.


Loss of appetite

Some people report that CBD causes them to lose their appetite — an effect that usually disappears after a few hours.


In some cases, a reduced appetite might be desired, for example to combat obesity, yet those who prefer to maintain their current appetite levels might want to try a different dosage form or avoid CBD altogether.


Low blood pressure

CBD has the potential to dilate blood vessels, which can lower blood pressure [3]. While this might be desirable for some, it might lead others to feel dizzy or lightheaded. Those with low blood pressure — or regardless of our blood pressure condition — should always consult a doctor before trying CBD.



Diarrhea is one of the most commonly reported side effects of CBD [4]. Those affected might benefit from a lower dose.



Drowsiness and fatigue are also potential side effects of CBD [4]. Whether or not this is an unwanted side effect  depends on the situation. While some use CBD specifically as a sleep aid, others might not be interested. It’s also important to know that CBD also affects each person differently. What might provoke sleepiness in one person might provoke sleeplessness in another person, which leads us to...


Sleep disorders

As mentioned, CBD can lead to feelings of tiredness. However, according to some testimonials, in rare cases CBD can lead to the opposite effect, to conditions such as insomnia. The exact reason for this is still unknown.


By the way, such seemingly paradoxical occurrences are not all that unusual: For example, one of the officially reported side effects of aspirin? Headaches.


Dry mouth

Dry mouth is the most often-reported side effect of CBD [5], as CBD that’s ingested via sublingual drops or mouth sprays can influence saliva formation.


To avoid this possible effect, CBD capsules might be a better alternative to CBD oil, as well as CBD creams or gels. Yet CBD that’s applied topically can produce different effects than CBD that’s ingested. 


CBD drug interactions

Taking CBD with other medications might increase the risk of unwanted symptoms of toxicity. Drug interactions have been reported with:


  • warfarin (anticoagulant or blood thinner)
  • amiodarone (antiarrhythmic for irregular heartbeats)
  • levothyroxine (thyroid conditions)
  • clobazam, lamotrigine and valproate (anti-seizure)

Who else should avoid CBD?


Pregnant and breastfeeding women are advised against using CBD because there are signs that it could influence labor contractions [7], and the results of an animal study suggest that CBD might impair embryo growth [8].


It still has not been confirmed whether or not CBD can damage the human liver. A study on mice concluded that ‘CBD exhibited clear signs of hepatotoxicity’ (or liver damage), ‘possibly of a cholestatic nature’, meaning decreased bile flow, and raised ‘serious concerns about potential drug interactions as well as the safety of CBD’ [9].


Critics of that study argue that the amount of CBD used on those mice was far above what might have been appropriate — as any ingredient will likely cause issues when taken in excess.

Those who suffer from a liver condition should consult a doctor before trying CBD. 


Conclusion: Potential side effects of CBD


Pregnant and breastfeeding women should avoid CBD, as studies suggest negative side effects during pregnancy, and there has not been enough research into CBD’s effects on breastfeeding. 


Those with liver issues, increased intraocular pressure or other pre-existing conditions, and those who take the aforementioned medications should always speak with a doctor before trying CBD.


Apart from that, CBD is considered to have a generally good safety profile for the general population. 


In addition, it’s particularly important to pay attention to the quality of the CBD and other ingredients contained in each CBD product. When buying CBD creams or CBD oils, always opt for high quality products that can demonstrate proof of safety and purity in order to guarantee that the product contains no impurities and that it doesn’t exceed the maximum limit of THC permitted by local authorities.


  1. CANNABIDIOL (CBD) Pre-Review Report Agenda Item 5.2 More Info
  2. CBD in marijuana may worsen glaucoma, raise eye pressure More Info
  3. A single dose of cannabidiol reduces blood pressure in healthy volunteers in a randomized crossover study More Info
  4. An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies More Info
  5. A Cross-Sectional Study of Cannabidiol Users More Info
  6. CBD and other medications: Proceed with caution More Info
  7. Effects of abnormal cannabidiol on oxytocin-induced myometrial contractility More Info
  8. Cannabinoids Exacerbate Alcohol Teratogenesis by a CB1-Hedgehog Interaction More Info
  9. Hepatotoxicity of a Cannabidiol-Rich Cannabis Extract in the Mouse Model More Info