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Does CBD Oil have Side Effects?

What are the side effects of CBD oil?

In 2018, CBD oil hit national headlines when the government agreed to legalise medical cannabis. This came about after families campaigned for their children that were suffering with severe epilepsy to be able to use it, with CBD a proven treatment. Since then, cannabis-derived products have hit the mainstream. Now it’s easier than ever to get hold of CBD — just pop down to your local Boots or order it online. 

An important aspect of Dragonfly CBD’s mission is to inform and educate people about the trustworthiness of CBD oil. And some people worry about its usage and side effects, so we’re here to clear things up.

The World Health Organisation's view of CBD

If taken properly, taking Dragonfly CBD does not cause any side effects — it’s generally considered safe. In 2018 the World Health Organisation (WHO) stated the following: “CBD is generally well tolerated with a good safety profile. Reported adverse effects may be as a result of drug-drug interactions between CBD and patients’ existing medications. Several countries have modified their national controls to accommodate CBD as a medicinal product. To date, there is no evidence of recreational use of CBD or any public health-related problems associated with the use of pure CBD.”

Side effects found in high-dose clinical trials

Although often mild, not long-lasting and easy to eliminate, CBD has been proven to cause some side effects in high-dose clinical trials, however. A case in point is a 2017 study whereby 120 people were prescribed high daily doses of CBD for 14 weeks. This was more than is typically found in an entire bottle of CBD oil. As a result, some side effects did come up, including somnolence (sleepiness), loss of appetite and diarrhoea. However, for nearly all the patients, these adverse effects occurred during the first few weeks while they were quickly raising their dosage. All the symptoms tended to subside after their dosages were lowered.

If you’re new to CBD and experience any of these side effects, it’s worth keeping to a moderate dose and experimenting until it gives you a balanced effect. Begin with the minimum dosage stated on the packaging for at least a week before slowly adjusting to your individual needs. This allows your body to get accustomed to the CBD and all-but eliminates the risk of side effects. To begin with, a low-concentration oil such as our Narrow Spectrum 1000mg would be your best bet. 

For a more detailed guide on CBD dosage and how to take it, see our full guide.

Taking CBD

Other potential minor side effects

Although CBD shouldn’t cause any major side effects if dosed properly, you might still experience minor side effects when taking it, including:

Dry Mouth

Dry mouth is a reported side effect of taking CBD. Specifically, this is when your mouth and eyes feel dry, which is why this is sometimes called ‘cotton-mouth’. To get rid of it, just make sure to keep hydrated.


Although the most common form is oil, CBD comes in a variety of forms, such as isolate, vapours, gums and cream. Because of this, the amount of CBD absorbed can vary with each product, meaning the chances of experiencing nausea will change too. This all also depends on how sensitive you are to getting nauseous. Once you settle into a regular dosage though, this shouldn’t be a problem.


While this is affected by other factors like dehydration and lack of food, light-headedness is another potential side effect of CBD. To avoid it, have some food in your system and water to hand when taking a CBD product.

Does CBD cause any side effects when taken with medication?

As noted by WHO, any side effects are likely to be the result of drug to drug interactions.

Prescription drugs are processed by your body in different ways. CBD is capable of occupying enzymes that your body uses to process certain medication. Like grapefruit, CBD is a more potent inhibitor of these enzymes. This means that if you take it with some prescribed pharmaceuticals, the CBD could pose a health risk by either increasing or decreasing levels of these medications in your bloodstream.

In short, a person currently taking prescription drugs needs to speak with a medical professional before using CBD. They will be able to give you accurate, personal advice on how to proceed in regards to dosage, timings and dealing with potential side effects.