CBD Oil Side Effects: What to Know Before You Buy

CBD Oil Side Effects

Does CBD oil have any side effects? Whether you’re a newbie or veteran CBD user, it’s always a good time to ask this question. In this article, we’ll provide the science that speaks about CBD oil side effects and the safety profile of CBD as a whole.  

What the science shows

One of the most recent and comprehensive studies on the side effects of CBD took place during 2011. The researchers from the University of Sao Paulo, Brazil, wanted to learn about the safety profile and side effects of cannabidiol in humans and animals. 

So, they analyzed a series of reports on this topic and came to the following conclusion. 

“CBD does not affect physiological parameters (heart rate, blood pressure, and body temperature), it does not affect gastrointestinal transit and it does not alter psychomotor or psychological functions.” 

In addition to these positive findings, the researchers concluded that CBD could be safe in humans and animals, but more clinical trials were necessary.  

A follow-up study performed in 2017

Fortunately, in 2017, two researchers updated and extended the scope of this 2011 study. Not only did they update the literature, but there were more clinical trials to assess. 

Having this extra information to study, meant they could make more definitive conclusions about the safety of CBD. 

Based on their research, they found that the side effects of CBD fared much better compared to the side effects of other drugs. The side effects they noted in patients included feelings of tiredness, changes in appetite, and diarrhea. 

We’ll explore the reasons patients experienced these CBD oil side effects. 

CBD oil side effects

The 2017 study found a few minor side effects in patients with epilepsy and psychotic disorders who used CBD oil in conjunction with their medications. We’ll explain each side effect in detail.


There are two main reasons why digestive upset may occur when consuming CBD oil. The first is consuming a poor quality CBD oil and the other is taking too high of a dose. 

To prevent this possible side effect from happening, it’s important to always buy CBD oil from a reputable company that lab tests its products for purity and potency.  

Change in appetite

When people consume CBD oil they may or may not experience a change in their appetite. Studies show that a shift in appetite can go either way — an increase or decrease. This could depend on the particular needs of each person. For instance, the body may take into account weight composition, age, the overall health of the person, and other factors. 

Science isn’t exactly sure why appetite changes occur. As more clinical trials take place, the answers will become clear. 


Those who take CBD oil regularly may have an easier time falling asleep. That’s because cannabis-based products like hemp-derived CBD oil can contribute to feelings of drowsiness or tiredness. This may not happen with everyone, but it’s one of the side effects that several studies have found. 

Even though CBD oil has been reported to have minimal side effects, the World Health Organization (WHO) found that, in general, CBD has a favorable safety profile in humans.

Report on cannabidiol from the World Health Organization (WHO)

In June 2018, the World Health Organization issued a report called Cannabidiol (CBD) Critical Review Report. Based on their findings, they concluded that “CBD was tolerated in all patients, with no signs of toxicity or serious side effects.” Additionally, the report stated that CBD is non-psychoactive and non-addictive.

However, if you’re taking prescription medications or want the opinion of your physician before consuming a CBD product, please consult with them first.

What about interactions with other drugs? 

Research shows that CBD can inhibit the activity of cytochrome P450. This is a group of liver enzymes that process and metabolize drugs, including pharmaceutical drugs. When someone takes large doses of CBD oil, it can temporarily deactivate cytochrome P450, and thus reduce the body’s ability to process (detox) medicinal compounds.

Again, it’s advisable to discuss any concerns you might have with your doctor beforehand. 

Final thoughts

Several studies and reports indicate that CBD oil has a favorable safety profile. Minor side effects may occur, but adverse CBD oil side effects are rare.