Known and Potential Side Effects of Cannabidiol (CBD)

Cannabidiol (CBD)Side Effects of CBD

CBD has few side effects and is considered a safe substance to take. These are the known side effects of CBD:

  1. Inhibition of hepatic drug metabolism/decreased activities of p-glycoprotein and other drug transporters
  2. Dry mouth
  3. Increased tremor in certain groups
  4. Low blood pressure
  5. Lightheadedness
  6. Drowsiness

Cannabidiol (CBD) is probably the best-known cannabinoid in the hemp plant, along with THC (which can only be present in quantities of 0.3% or less in legal hemp CBD products). Although the two compounds share the same roots, they don’t carry the same traits and their influences on the human body are very different.

THC is the compound that gets the user high, and it does this by binding to the CB1 receptor in the brain. It does provide some health advantages thanks to its unique properties, but the side effects usually outweigh the benefits. This is why THC is not regarded as a suitable solution for many people.

CBD, on the other hand, has a greater affinity to the CB2 receptor, interacting differently with the nervous system without eliciting any psychoactive results. Instead, CBD health advantages are numerous. CBD is often regarded as a better option than THC, as CBD has fewer side effects.

Moreover, CBD counteracts the psychoactivity of THC. We won’t detail these aspects here, but you can read our previous articles to learn more about the positive effects of cannabidiol and about the differences between THC and CBD.

For now, let’s return to CBD side effects and its actions and interactions inside the human body.

Potential Side Effects of Cannabidiol (CBD)

There are dozens of studies that demonstrate the outcomes of cannabidiol as a modality for various conditions. Most of these studies conclude that this cannabinoid is safe and virtually free of side effects.

This review paper on the safety and side effects of cannabidiol by the NCBI, for example, suggests that controlled cannabidiol administration is safe and non-toxic in humans and animals. It also does not induce changes in food intake, nor does it affect physiological parameters like heart rate, body temperature or blood pressure. Also, according to this review paper, “high doses up to 1,500 mg/day of CBD are reportedly well tolerated in humans.”

In 2018, the World Health Organization updated its stance on CBD , recommending that it be removed from drug schedules worldwide. The  2018 Farm Bill in the U.S. followed , making hemp-derived CBD products legal across the country.

Hemp CBD has been on the rise ever since, so it’s important to know what potential side effects you could experience while taking it. Even though hemp has a good safety profile and has very few known side effects, minor side effects have been reported by some. Here’s what you should know before taking CBD.

1. Inhibition of hepatic drug metabolism

The NCBI study does mention some potential side effects for cannabidiol, such as the inhibition of hepatic drug metabolism and decreased activity of p-glycoprotein. CBD can indeed interact with a series of pharmaceuticals, as it inhibits the activity of some liver enzymes called cytochrome P450 . This family of enzymes metabolizes most of the pharmaceutical drugs used to treat humans.

If one takes high amounts of CBD, the cannabinoid can temporarily neutralize the activity of P450 enzymes and thus alter the way drugs are metabolized inside the body. This action of CBD can be regarded as a side effect, but it’s not always a negative trait, as the deactivation of P450 enzymes is one of the mechanisms through which CBD neutralizes THC as well.

Putting this in perspective, eating a portion of grapefruit would have a similar effect on the aforementioned liver enzymes. So neutralizing P450 enzymes should be viewed as a minor side effect of cannabidiol. However, if you are taking pharmaceutical drugs and wish to take CBD, you should discuss any potential complications regarding reduced P450 enzyme activity with your doctor and/or pharmacist.

2. Dry mouth

Another reported side effect of CBD administration is an unpleasant dry sensation in the mouth. This effect seems to be caused by the involvement of the endocannabinoid system in the inhibition of saliva secretion. A study published by Argentinian researchers back in 2006 showed that cannabinoid receptors (type 1 and 2) are present in the submandibular glands which are responsible for producing saliva.

The activation of these receptors alters the salivary production, leading to mouth dryness (also referred to as “cotton-mouth”). As a side effect, dry mouth is easily handled by drinking plenty of water or using a rehydrating mouth rinse.

3. Increased tremor with high servings of CBD

Early research suggests that CBD taken in large amounts may worsen tremor and involuntary muscle movement in certain individuals . Yet, there are also studies that suggest that cannabidiol is safe and well-tolerated by patients affected by certain severe conditions. If this occurs, reducing the serving should reduce this potential side effect.

People whose conditions include tremor should consult their doctor before taking CBD–and also begin any regimen by taking smaller amounts.

4. Low blood pressure

Higher amounts of CBD oil can cause a small drop in blood pressure, usually within a few minutes of the CBD entering your system. This drop in blood pressure is often associated with a feeling of lightheadedness. If you are taking medication for blood pressure, you should consult your doctor before taking CBD.

5. Lightheadedness

Lightheadedness can be caused by the drop in blood pressure that can affect those using higher servings. This side effect of CBD is temporary and can often be resolved by drinking a cup of coffee or tea.

6. Drowsiness

In higher servings, CBD can cause drowsiness. If you are affected this way, you should not operate machinery or drive a vehicle. In most cases, however, CBD appears to encourage alertness during the day .

If you need to know more about the side effects of CBD, please contact us – we are happy to help answer any questions you might have.


  1. Safety and side effects of cannabidiol (NCBI/NIH)
  2. Safety and Side Effects of Cannabidiol, a Cannabis sativa Constituent (ResearchGate)

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