Epidiolex (cannabidiol) is a prescription drug used to treat seizures due to certain conditions. Epidiolex can cause side effects that range from mild to serious. Examples include liver problems, decreased appetite, and sleepiness.

Specifically, Epidiolex is used in adults and certain children to treat:

The active ingredient in Epidiolex is cannabidiol. The drug comes as an oral liquid that you swallow.

Keep reading to learn about common, mild, and serious side effects that Epidiolex can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during their Epidiolex treatment. Examples of the drug’s commonly reported side effects include:

  • decreased appetite
  • diarrhea
  • increased liver enzymes, which may indicate liver damage*
  • sleepiness*
  • weight loss*

* To learn more about this side effect, see the “Side effects explained” section.

Mild side effects have been reported with Epidiolex. These include:

  • decreased appetite
  • diarrhea
  • fatigue (low energy)
  • fever
  • nausea or vomiting
  • skin rash
  • sleepiness*
  • trouble sleeping
  • weakness
  • weight loss*

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop Epidiolex treatment unless your doctor recommends it.

Epidiolex may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section.

Serious side effects have been reported with Epidiolex. These include:

  • infections, including pneumonia
  • increased liver enzymes, which may indicate liver damage*
  • severe sleepiness that can lead to trouble thinking or functioning as usual*
  • suicidal thoughts or behaviors

If you develop serious side effects while taking Epidiolex, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Epidiolex, visit MedWatch.

ALLERGIC REACTION

For some people, Epidiolex can cause an allergic reaction.

In general, symptoms of allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue Epidiolex treatment.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Epidiolex, they may have you switch to a different treatment.

Get answers to some frequently asked questions about Epidiolex’s side effects.

Does Epidiolex cause weight gain?

No, weight gain wasn’t a reported side effect in studies of Epidiolex. People taking the drug were more likely to report weight loss. You can read more about weight loss with Epidiolex in the “Side effects explained” section.

If you’re experiencing weight gain that concerns you, talk with your doctor. They can determine the most likely cause and suggest ways to manage it.

Is there a risk of dependence with Epidiolex?

No, dependence wasn’t reported in studies of Epidiolex. Physical dependence is a condition that occurs when your body relies on a drug to function as usual. If you’re physically dependent on a drug and stop taking it suddenly, you may experience withdrawal symptoms. These can be uncomfortable and serious in some cases.

Adults taking Epidiolex in studies didn’t have with withdrawal symptoms when they stopped the drug. This probably means that Epidiolex doesn’t cause physical dependence.

If you’re concerned about how Epidiolex may affect you, talk with your doctor. Epidiolex isn’t a controlled substance. But if you’ve had problems with controlled substances in the past, tell your doctor. Together, you can decide whether Epidiolex is right for you.

Learn more about some of the side effects Epidiolex may cause.

Increased liver enzymes

Increased liver enzymes were a very common side effect reported in studies of Epidiolex. This side effect may indicate liver damage and may cause symptoms such as:

  • dark urine
  • fatigue (low energy)
  • itchiness
  • jaundice (yellowing of your skin or whites of your eyes)
  • loss of appetite
  • nausea or vomiting
  • pain in the upper right side of your abdomen

Factors that can increase the risk of liver problems when taking this drug include:

  • taking certain other drugs, such as valproate or clobazam
  • consuming high dosages of Epidiolex
  • having high liver enzyme levels before starting Epidiolex

What might help

Due to the risk of liver problems, your doctor will likely check your liver function tests before starting Epidiolex. They’ll probably also check these tests at 1 month, 3 months, and 6 months after starting treatment. After that, they’ll check them from time to time.

If you have symptoms of liver problems during Epidiolex treatment, call your doctor right away. They may recommend stopping Epidiolex treatment.

Sleepiness

Sleepiness was a very common side effect reported in studies of Epidiolex. This side effect can be mild or severe. Severe sleepiness is called somnolence, sedation, or lethargy.

Severe sleepiness may cause trouble thinking or functioning as usual.

Drinking alcohol or taking other sedating medications with Epidiolex can make sleepiness worse. Examples of sedating medications include:

What might help

Sleepiness from Epidiolex is most common at the start of treatment. It usually gets better with time. Until you know how Epidiolex affects you, use caution driving, operating machinery, or doing other tasks that require alertness.

Call your doctor if sleepiness is severe or doesn’t get better.

Weight loss

Weight loss was a very common side effect reported in studies of Epidiolex. This side effect was likely dose-related. This means that people taking higher doses of Epidiolex reported more weight loss than people taking lower doses.

Keep in mind, Epidiolex can also cause decreased appetite. This may play a role in weight loss that can happen with the drug.

What might help

If you experience weight loss that concerns you, talk with your doctor. They can determine the most likely cause and suggest ways to manage it.

Keeping track of side effects

During your Epidiolex treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start a new drug or combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Sharing notes with your doctor will help them learn more about how Epidiolex affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information to consider before taking Epidiolex.

Warnings

Epidiolex can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Epidiolex is a good treatment option for you.

Talk with your doctor about your health history before you take Epidiolex. Be sure to tell them if any of the following factors apply to you:

  • depression or other mood conditions
  • liver problems
  • history of misuse or dependence of alcohol or drugs
  • history of suicidal thoughts or behaviors
  • previous allergic reaction to Epidiolex
  • pregnancy
  • breastfeeding
  • alcohol consumption

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.