The World Health Organization describes CBD as “generally well tolerated with a good safety profile”. Many people take it regularly without any problems; however, for some, it can produce side effects.
The information we’ve gathered here has been collected from scientific studies. Because scientific studies are usually undertaken to answer specific questions about CBD they’re specifically focused on certain outcomes. As a result, there may be side effects that have not yet been reported.
Note: We are not medical professionals and this article isn’t exhaustive. If you have any concerns or experience any side effects when taking CBD, you should stop taking it immediately and speak to your doctor.
CBD produces slightly different results for each person depending on factors such as health, body mass, body chemistry and age. The same is true of side effects; many people don’t experience any, but some may notice more than one.
The most common are considered to be mild and can include:
Some studies have reported that high doses may increase the risk of more concerning effects such as:
To understand the risks of these side effects, it’s important to know more about how they were discovered. It’s also useful to find out what is known about the causes of these side effects.
The glands that produce saliva are also home to cannabinoid receptors. When you take CBD, it interacts with these receptors, which makes it harder for them to activate the chemical signals to keep producing saliva.
Most CBD products, including hemp extracted CBD oil, spend very little time in your mouth, so this effect will likely be mild. If you do experience it, make sure you have access to a small amount of water when you take CBD. That will help keep your mouth fresh and get the saliva flowing again.
Some studies have reported that large amounts of CBD can produce discomfort, diarrhoea and vomiting. There is no feature of CBD that has yet been pinpointed as the cause of these problems; the current theory is that some people’s digestive systems can’t process the oil.
It’s also likely that these problems could be as a result of higher concentrations, or of other ingredients included in the oil. Hemp seed oil and MCT oil are commonly mixed with CBD to act as a carrier; the coconut in MCT oil known to cause mild discomfort in some people and even diarrhoea.
One of the main studies that linked CBD to diarrhoea looked at the effect of the drug Epidiolex on people with epilepsy. 19% of the participants reported diarrhoea as a side effect. However, they were receiving measures of up to 50mg of CBD per kg of body weight per day, so the high concentration could have been a factor.
Several studies found that more 30% of participants reported a change in appetite. For some, it was an increase, while for others it decreased. It’s likely that over a longer period these changes could affect your weight. It’s worth noting that most of the studies that reported these findings involved children and used daily amounts of more than 150mg of CBD.
CBD has been found to interact with several medications. In most cases, it either slows or speeds up the metabolism of the medicine, particularly those that interact with the CYP450 enzyme. This can have a significant impact on how the medicine works, so the Food Standards Agency doesn’t recommend CBD for anyone taking medication. If you have a medical condition or take pharmaceutical drugs, you must speak to your doctor before using CBD.
In 2019, research conducted with mice found that when they were given CBD regularly, some showed increased levels of enzymes that are used as an indicator of liver damage. However, the damage occurred after regular amounts of CBD that are the equivalent to a human measurement of between 900mg and 1300mg per day.
Even a single measure of highly concentrated CBD can relax the walls of blood vessels reducing blood pressure. If it drops too low, it may cause dizziness and other complications. The study that found this used 600mg of CBD, but some consumers have reported signs of low blood pressure after smaller amounts.
CBD is not known to cause an allergic reaction; however, not all CBD products are produced in the same way. From brand to brand, they’re likely to contain different carrier oils, flavours, additives and other additional ingredients.
Before you try a new product, make sure you know exactly what it contains and check if it has come into contact with any allergens during production. Get to know the brand, make sure it has a reputation for quality and safety. Look for information about where they source their ingredients and if necessary, contact them to get details about their manufacturing practices.
This list is not exhaustive and there are many areas of CBD and its effects that need further study. There are also several other side effects such as irritability, fatigue and drowsiness that have been reported anecdotally but have not yet been reported in scientific research.
It’s also important to follow the latest guidance from the Food Standards Agency which states:
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We are a small but mighty team of experienced natural health researchers. We follow strict selection criteria and test everything we retail: from ground-breaking food supplements to natural skincare products. Our main area of expertise is CBD.