Fycompa (perampanel) is a prescription drug used to treat seizures in people with epilepsy. Fycompa can cause side effects that range from mild to serious. Examples include fatigue, sleepiness, and dizziness.

Specifically, Fycompa is prescribed for adults and certain children to treat:

  • partial-onset seizures in people ages 4 years and older with epilepsy (for this use, Fycompa may be prescribed by itself or along with other seizure medications)
  • generalized tonic-clonic seizures in people ages 12 years and older with epilepsy (for this use, Fycompa is prescribed along with other seizure medications)

The active ingredient in Fycompa is perampanel. (An active ingredient is what makes a drug work.) Fycompa comes as both an oral tablet and an oral liquid suspension.

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

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

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

Note: After the 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 Fycompa, visit MedWatch.

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

  • sleepiness
  • dizziness
  • irritability
  • anxiety
  • fatigue
  • vertigo (spinning sensation in your head)
  • difficulties with balance and walking
  • bruising
  • headache
  • nausea
  • vomiting
  • weight gain*
  • abdominal pain
  • mild allergic reaction*†

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 taking Fycompa unless your doctor recommends it.

Fycompa 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 below.
† An allergic reaction is possible after taking Fycompa, but this side effect wasn’t reported in studies.

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

If you develop serious side effects while taking Fycompa, 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 “FAQ about Fycompa’s side effects” section below.
† To learn more about this side effect, see the “Side effects explained” section below.
An allergic reaction is possible after taking Fycompa, but this side effect wasn’t reported in studies.

Help is out there

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

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 are not in the same household, stay on the phone with them until help arrives.

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

How do side effects of Fycompa compare with those of Keppra and Keppra XR?

Fycompa, Keppra, and Keppra XR are prescribed to treat certain types of seizure, and all have similar mild side effects, such as sleepiness and irritability.

They also may cause severe side effects that are similar, including:

  • suicidal thoughts and behaviors
  • withdrawal seizures*
  • uncoordinated movements

Fycompa, Keppra, and Keppra XR all have warnings for aggressive behavior. However, only Fycompa has a boxed warning about behavior changes. (A boxed warning is the most serious warning from the FDA.) While rare, aggression was reported to be life threatening in the drug’s studies.

Keppra and Keppra XR may cause some different side effects than Fycompa. For example, Keppra and Keppra XR may cause increased blood pressure or blood abnormalities. And weight loss has been reported with Keppra and Keppra XR, while weight gain† has been reported with Fycompa.

This isn’t a complete list of side effects reported with Fycompa, Keppra, and Keppra XR. See each drug’s prescribing information and talk with your doctor or pharmacist for more details.

* See the “Is withdrawal a possible side effect of Fycompa?” question and answer below for more information.
To learn more about this side effect, see the “Side effects explained” section below.

Is withdrawal a possible side effect of Fycompa?

Yes, as with all antiseizure medications, suddenly stopping Fycompa may cause seizures as a withdrawal symptom.* Other symptoms of withdrawal include:

If you and your doctor decide you’ll stop taking Fycompa, they may have you decrease your dose slowly over time. If you’re having problems with this medication and need to stop right away, talk with your doctor. Do not stop taking Fycompa unless they recommend it.

* Withdrawal symptoms are side effects that can occur when you stop taking a drug your body has become dependent on.

Does Fycompa cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away even after you stop taking the drug.

Examples of long-term side effects reported in Fycompa’s studies include:

  • broken bones or head injuries from falls
  • suicidal thoughts or actions
  • severe allergic reaction, including DRESS*

Talk with your doctor to learn more about possible side effects of Fycompa and how long they may last.

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

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

Risk of behavioral or psychiatric changes

Serious behavioral and psychiatric changes were an uncommon side effect reported in studies of Fycompa. Behavioral or psychiatric changes may cause symptoms such as:

  • personality changes
  • aggressive, violent behavior
  • thinking about or planning to harm someone
  • irritability
  • anger
  • hostility
  • anxiety
  • feeling overly suspicious or distrustful
  • extreme mood swings
  • confusion
  • memory problems
  • hallucinations (seeing or hearing things that aren’t really there)

Factors that can increase the risk of behavioral or psychiatric changes when taking this drug include a personal or family history of mental health disorders. This includes depression, anxiety, and thoughts or actions that are suicidal or homicidal (about harming others).

What might help

Ask for the assistance of trusted family, friends, and professionals to help monitor these symptoms when you start taking Fycompa. They might be among the first to detect unusual behaviors and offer help.

If you have behavioral or psychiatric changes during Fycompa treatment, contact your doctor right away. If you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Weight gain

Some people experience weight gain while taking Fycompa. In studies of the drug, the average weight gain was 1.1 kilograms (kg), which is about 2.5 pounds (lb).

Taking a higher dose of Fycompa may increase the risk or severity of weight gain. Other factors may also play a role, such as taking other medications that can cause weight gain.

What might help

If you have weight gain during Fycompa treatment, consider the following options to help manage your weight:

  • regular exercise
  • a balanced, nutritious diet
  • a good sleep routine
  • relaxation techniques to reduce stress eating

If you have difficulty managing your weight, ask your doctor to evaluate your medications or possible underlying reasons. They may suggest decreasing your Fycompa dose or changing to another drug that won’t cause weight gain.

Allergic reaction

An allergic reaction is possible after taking Fycompa, but this side effect wasn’t reported in studies. Symptoms of an allergic reaction can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

Fycompa can also cause a rare allergic reaction called DRESS. Symptoms may include:

DRESS is a life threatening allergic reaction that can damage the heart, kidneys, liver, and other bodily organs. Hyperactive eosinophils, a type of white blood cell, are the cause of organ damage. If you develop a rash with fever, seek immediate medical care. DRESS can be treated if it’s caught early.

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. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Fycompa, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty 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 Fycompa, they may have you switch to a different treatment.

Keeping track of side effects

During your Fycompa 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 taking a new drug or using a 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

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

Below is important information you should consider before taking Fycompa.

Boxed warning: Risk of behavioral or psychiatric changes

Fycompa has a boxed warning for the risk of behavioral or psychiatric changes. A boxed warning is the most serious warning from the FDA.

To learn more, see the “Side effects explained” section above.

Fycompa and misuse

Due to the risks of misuse and dependence*, Fycompa is a class III controlled substance in the U.S. This means it has an approved medical use but may be misused for other purposes. It also means government agencies, doctors, and pharmacists pay close attention to how the drug is prescribed and taken.

If you have a history of alcohol or drug misuse, you may be more likely to become dependent on or misuse Fycompa. Only take this drug exactly as your doctor has prescribed.

* With misuse, a drug is taken in a way or for a reason other than how or why it was prescribed. Misuse can lead to dependence, which is when your body gets used to a drug and needs it for you to function as usual.

Other warnings

Fycompa can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether this drug is a good treatment option for you. Talk with your doctor about your health history before starting Fycompa. Be sure to tell them if any of the following factors apply to you:

  • history of mental health disorders such as depression or anxiety
  • history of suicidal thoughts or actions
  • history of aggressive or violent behavior or thoughts of harming others
  • liver or kidney problems
  • alcohol consumption
  • history of substance misuse
  • taking other prescription or over-the-counter medications, supplements, vitamins, or herbs
  • past allergic reaction to Fycompa
  • pregnancy
  • breastfeeding

Alcohol and Fycompa

You should not consume alcohol during Fycompa treatment. This combination can cause central nervous system depression, which could lead to coma.

In studies, researchers found that consuming alcohol while taking this medication made the side effects of dizziness and drowsiness worse. It also worsened mood and anger.

If you have questions about consuming alcohol during Fycompa treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Fycompa

Fycompa is usually prescribed for someone who’s pregnant or breastfeeding only if the benefits of treatment outweigh the potential risks to the fetus or child.

Pregnancy

It’s not known whether it’s safe to take Fycompa during pregnancy. There isn’t enough information to understand the potential risks to fetal development when pregnant people take this medication.

If you’re pregnant or planning to become pregnant, talk with your doctor before starting Fycompa.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during Fycompa treatment. However, it’s best to avoid levonorgestrel-containing birth control pills because Fycompa may reduce their effectiveness. A form of nonhormonal birth control may be a better option.

If you take this drug while pregnant, consider signing up for The North American Antiepileptic Drug Pregnancy Registry by visiting the website or calling 888-233-2334. A pregnancy registry collects information about the safety of certain drugs when taken during pregnancy.

Breastfeeding

It’s not known whether Fycompa is safe to take while breastfeeding.

It’s important to consider the advantages of breastfeeding for a child’s growth and health. However, it’s also essential to assess the parent’s need for Fycompa, and the possible harm their untreated condition might cause the child who would be breastfed.

If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication.

Like most drugs, Fycompa can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks.

If you have questions about side effects Fycompa can cause, talk with your doctor. Examples of questions to help get you started include:

  • Will Fycompa affect my thinking and response times?
  • Can this drug cause bone loss?
  • How likely am I to become dependent on Fycompa?
  • Can I drive while taking this medication?
  • When should I call you about side effects caused by Fycompa?

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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.