Does CBD Oil Have Any Known Side Effects?

Written by Cathy Rozyczko — Edited by Jason Brett on September 27, 2021

People are quickly becoming aware of the potential benefits of CBD oil, but this awareness has lead to one very important question: Does CBD oil have any known side effects?

Unfortunately, the answer isn’t a simple “yes” or “no.”

Given that so many people are touting CBD oil as a potential solution for a wide variety of conditions, it is important to be able to separate the facts from the fiction. Keep in mind, just as you may feel the benefits of CBD oil in a different way than the next person, people may also feel side effects others will never experience.

Below, you’ll find information on what the current research has to say about CBD oil’s potential side effects.

Possible CBD Oil Side Effects

In the vast majority of people, CBD oil is very well tolerated with few reported side effects. While these side effects are minor and rare, it is important that CBD oil users understand that these experiences are possible.

If you experience any of the following side effects, consult with your doctor immediately. This guide is not meant to provide medical advice—only information—and all decisions you make regarding your health should include some input from a licensed physician. You can also speak with a cannabis doctor whose specialty is using CBD oil as a medical treatment.

Diarrhea

Diarrhea is a potential side effect that has been linked to the use of CBD oil.  The 2015 study in which diarrhea was reported as a side effect was conducted on people between the ages of 1 and 30 who had severe epilepsy. The study examined the effects of the epilepsy drug Epidiolex, which contains cannabidiol (CBD) as an active ingredient. Of the 214 participants, 19% reportedly experienced diarrhea. It is not entirely clear as to whether CBD was responsible for this side effect, as it has not occurred in other studies.

Two factors to consider, which were potential reasons for the diarrhea experienced in the study, are CBD carrier oils and dosage.

The study posited the diarrhea could have been caused by the sesame oil mixed with and used as a carrier oil for the CBD isolate taken by the test subjects. In general, it’s entirely possible that other ingredients in CBD oil can contribute to gastrointestinal distress. Coconut oil and MCT oil are often used as carrier oils in commercial CBD products, and have been known to cause diarrhea and loose stool, particularly in people who are not used to taking it.

Too, the dosage and concentration of CBD in the study were relatively high compared to your typical, commercial CBD products. Subjects started by receiving 2mg-5mg of 99% pure CBD per 1 kg of body weight (1 kg=2.2 lbs) per day, and dosages were increased by 2-5mg/kg body weight each week, with some subjects eventually taking up to 50mg of CBD per kg of body weight per day. Consider how much CBD oil you would need to consume as a participant in this 12-week study, and then consider the CBD Oil Review Serving Standard: 25 mg of CBD taken twice daily. By week two of the study, you’d likely ingest double the amount of cannabidiol suggested in the CBD Oil Review Serving Standard on a daily basis.

If  you experience diarrhea, stop using CBD oil for a day or two to make sure it isn’t being caused by something else. If you find the diarrhea has gone away, perhaps you just need to lower your dosage or seek out a CBD product that doesn’t use a carrier oil, like CBD shatter, vapes, or even gummies. As always, consult with your doctor if you have questions or concerns.

Changes in Appetite

While some studies have found that the use of CBD oil increased appetite in test groups, other studies have reported the opposite. A thorough review of the potential side effects of CBD oil found “when weight and appetite were measured as part of a measurement battery for side effects, results were inconclusive,” in test subjects who were given regular doses of CBD over a long period of time.

More research will need to be done to definitively say whether CBD oil increases or decreases appetite in its users. Ultimately, CBD oil’s effect on appetite could just vary from person to person based on their biology or, could very well not be due to the CBD at all. Like diarrhea, an increase or decrease in appetite following CBD consumption could be the result of another ingredient in the CBD product you’re consuming.

Fatigue

As with the other side effects of CBD oil, fatigue seems to be a symptom that can vary greatly from person to person. While some studies have reported increased fatigue in patients, these have generally been when testing a CBD/THC combined product. This factor aside, there are a number of studies that actually report decreased fatigue in participants using CBD oil. (1)(2)(3)

Dry Mouth

Many marijuana users will be familiar with the sensation of dry mouth. According to a 2006 study, this phenomenon is likely due to the inhibition of cannabinoid receptors present in salivary glands.

While dry mouth has been listed as a side effect in studies examining the effect of cannabis on certain conditions, most of this research has used a mixture of tetrahydrocannabinol (THC) and CBD; THC is well known to bind directly to CB1 and CB2 cannabinoid receptors while CBD indirectly activates them. This could mean THC is mainly responsible for the dry mouth associated with cannabis use—more research is needed to determine whether cannabidiol alone affects salivary production.

Can CBD oil interact with my medication?

Yes.

CBD oil inhibits the cytochrome P450 enzyme system.  Found in the liver, the cytochrome P450 enzymes are responsible for metabolizing toxic substances, including 70-80% of the medications taken today. This means that many prescription medications may be impacted by the use of CBD oil.

Because CBD oil slows down drug metabolization, certain medications take longer for the body to process. This results in a larger amount of that medication being present in your system at any given time and may possibly lead to adverse side effects or overdose.

For individuals currently taking prescribed medications, particularly steroids, antibiotics, and/or antidepressants, be sure to talk to your doctor before using CBD oil. In most cases, an adjustment in the dosage of your medication will be necessary.

Can You Overdose on CBD Oil?

As with anything, moderation is important when consuming CBD oil. It is important that you follow dosage guidelines and take into account your weight and health requirements. With this being said, all research points to it being incredibly unlikely that you could overdose on CBD oil and there have been no known cases of overdose.

The process of overdosing occurs when a toxic amount of a drug or drugs are present in the body. CBD oil is non-toxic and cannabis in general has not been shown to increase the risk of death in those who use it. In fact, some studies have reported that doses as high as 1500mg per day were well tolerated by test subjects. Considering average dosages are in the range of 50-60mg per day, this indicates an overdose is highly unlikely.

On a closing note, the National Cancer Institute has even stated, “Because cannabinoid receptors, unlike opioid receptors, are not located in the brainstem areas controlling respiration, lethal overdoses from Cannabis and cannabinoids do not occur.”

Who Should Avoid CBD Oil?

CBD oil products that contain no THC or only trace amounts pose a minimal risk to the consumer. But there are some people who should be careful.

Because of obvious ethical reasons, testing around the safety of CBD oil in children and pregnant women is limited. However, the studies that do exist seem to indicate CBD oil may be safe for children. In particular, children struggling with epilepsy and ADHD have found positive results. However, is always best to discuss using CBD oil with a pediatrician before giving it to a child.

It is not understood how CBD oil can impact a growing fetus so it is best for pregnant women to avoid using it. At the very least, pregnant women should consult their physician or OB/GYN before they begin. These medical professionals can help women understand the potential risks and make a fully informed decision.

Finally, when it comes to couples who are trying to have children, the effect CBD oil has on successful conception exists very much in a gray area. There are studies to suggest CBD oil’s effect on fertility could be negative, though there is also a chance CBD could help manage external factors that prevent pregnancy, like stress and nicotine addiction. So, you’re trying to conceive, CBD oil may not be a viable option for you at this time. As always, consult with your doctor.

All in all, CBD oil is largely free of side effects but there are, of course, possible exceptions. To avoid a potentially negative experience, talk to your physician, take the lowest dose you need to feel results, and monitor how you feel.

For more information about CBD oil and how it could impact you, check out this list of recommended reading:

• How Does CBD Affect the Endocannabinoid System?
• Should You Mix CBD Oil and Caffeine?
• What’s the Difference? CBD Isolate vs Full-Spectrum CBD Oil
• Can CBD Oil Improve Memory?
• Can CBD Oil Get You High?

Learn More About CBD