What Are The Side Effects of CBD?

CBD has just a few mild side effects, and does not affect the major functions of the body.

In recent years, cannabidiol (CBD) has become a popular remedy for many conditionsincluding anxiety, epilepsy, pain, and MS.

CBD is a non-psychoactive compound found in marijuana. Unlike THC, CBD does not cause a euphoric high or mind-altering effects.

CBD interacts with the endocannabinoid system, which has far-reaching effects on the whole body. It has antiemetic, anticonvulsant, antipsychotic, and analgesic properties, among many others.

As interest in CBD’s benefits has surged, so has interest in its potential side effects. Overwhelmingly, research suggests that CBD has only a few mild side effects including fatigue, appetite changes, diarrhea, and changes in the metabolism of other drugs.

When compared to other drugs, CBD’s list of side effects is quite short. They are also more common if you’re using a very high dose.

Risks and Side Effects of CBD

(Photo: Shutterstock)

Overall, CBD is considered to be well-tolerated in humans, even at high doses or when taken for long periods of time. Unlike THC, CBD does not have any psychoactive side effects.

Most people do not experience side effects from using CBD. Several animal and human studies have reported no side effects of treatment with CBD. However, other studies have reported a few minor side effects that may affect some people.

The most common side effects of CBD include:

  • Fatigue
  • Appetite changes
  • Diarrhea
  • Changes in the liver’s ability to process drugs

Other possible side effects:

  • Worsening of HIV symptoms
  • Reduction of fertility

CBD can be safely used at high doses without negative effects. Doses of up to 1500mg per day have been reported as safe. For reference, some people benefit from doses as low as 15mg.

Studies show that the lethal dose of CBD is very high. Scientists are not sure of the exact lethal dose of CBD in humans, as there are no known reports of death caused by CBD. A 1981 study found that a dose of 200mg per kg of body weight caused death in rhesus monkeys.

What Do Studies Say?

(Photo: Shutterstock)

2011 review of 132 scientific studies concluded that CBD has very few side effects and does not majorly impact bodily functions.

Essential bodily functions such as heart rate, body temperature, blood pressure, motor functions, psychological function, and gastrointestinal transit were found to be unaffected by CBD.

The major side effects included CBD’s impact on liver metabolism of certain drugs, a possible worsening of HIV symptoms, and a possible impact on fertility.

Another group of researchers reviewed the safety and side effects of CBD in 2017. Many studies on CBD were conducted between 2011 and 2017, so the researchers were able to review an additional 74 articles.

This group of researchers found mild side effects of CBD, including fatigue, diarrhea, and changes in appetite.

Effect on Drug Metabolism

CBD can affect the liver’s ability to process certain drugs and medications.

In a 2011 review, scientists found that CBD was a “potent inhibitor” of liver enzymes involved in drug metabolism.

A class of liver enzymes called cytochrome P450 is involved in metabolizing many drugs. CBD inactivates specific forms of this enzyme, making the liver less effective at processing certain drugs. This is very similar to the way that grapefruits can interact with medications.

This means that if you take any prescription medications, it’s important to talk to your doctor before combining them with CBD.


2014 study of medical marijuana users found that patients treated with high-CBD strains experienced fatigue.

However, the marijuana used in the experiment contained some THC, so it is not clear to what extent the drowsiness can be attributed to CBD. THC is known to induce sleepiness.

2015 study on CBD’s effectiveness for epilepsy found that tiredness was the most commonly reported side effect of the drug.


Diarrhea was reported as a common side effect of CBD treatment in a 2015 study on CBD for epilepsy.

However, it is not clear whether this side effect is specific to those with epilepsy, as it was found in other studies that CBD does not impact gastrointestinal transit time (which would be shortened in the case of diarrhea).

It’s also important to note that the doses used in the study were extremely high.

Appetite Changes

A few studies have reported changes in appetite resulting from CBD use.

In a Dutch study from 2014, people who used a high-CBD strain of marijuana reported mild changes in their appetite. However, appetite changes were stronger in those who used a high-THC strain.

Since there was still THC in the high-CBD strain, it’s difficult to tell whether the effects are due to CBD.

Effect on HIV Patients

In a 2011 review, researchers concluded that CBD may worsen the disease progression of HIV. They also found results that suggested it could make it easier to become infected with HIV if exposed to the virus.

The researchers note that some studies found a biphasic effect: a beneficial effect at low doses, and a negative effect at high doses.

However, these side effects only impact those who have been exposed to or infected with the HIV virus.


1986 study found that male rats who were exposed to CBD produced 20% less sperm than controls. They also produced significantly fewer live offspring.

Even more interestingly, male offspring of female rats exposed to CBD also produced 20% less sperm, even if they were only exposed in the womb.

Other studies have reported that CBD can impact levels of sex hormones such as including progesterone, testosterone, and estradiol.

Overall, it’s a good idea to avoid the use of drugs, including CBD, if you are trying to conceive.

How To Reduce Side Effects

(Photo: Shutterstock)

If you would like to reduce your chances of experiencing side effects from CBD, it’s important to use the correct dose and make sure any medications you are taking do not interact with CBD.

When trying to determine the correct dosage for patients, doctors often use a process called titration. Titration involves slowly increasing the dose until the patient achieves the most relief of symptoms with minimal side effects.

If you are experiencing side effects, you may be using too high of a dose. You can use dose titration to find a dose that works for you, but does not produce side effects.

When it comes to any medication, it’s always better to use the smallest dose that works. Since side effects increase with dosage, a smaller dose means you will have a lower chance of experiencing negative side effects.

It’s also important to talk to your doctor about any drug interactions between CBD and any medications you are currently taking.


CBD can be helpful for a number of conditions, but it may cause mild side effects in some people. These include fatigue, appetite changes, diarrhea, and changes in the liver enzymes responsible for drug metabolism.

For those who have been exposed to HIV, or who are trying to conceive a child, CBD may have negative side effects. It’s recommended to avoid using CBD if you are in one of these categories.

It’s important to get the dose right to minimize your risk of side effects from CBD. If you always use the smallest dose that gives you relief, you will be less likely to experience side effects.

Because CBD can interfere with the metabolism of some drugs, it’s a good idea to check with your doctor before combining CBD with other medications.