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Fycompa Side Effects

Generic name: perampanel

Medically reviewed by Philip Thornton, DipPharm. Last updated on Feb 16, 2022.

Note: This document contains side effect information about perampanel. Some of the dosage forms listed on this page may not apply to the brand name Fycompa.


Common side effects of Fycompa include: abnormal gait, aggressive behavior, balance impairment, dizziness, drowsiness, falling, hostility, ataxia, fatigue, and irritability. Other side effects include: anxiety, back pain, blurred vision, vertigo, and weight gain. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to perampanel: oral suspension, oral tablet


Oral route (Tablet; Suspension)

Serious or life threatening psychiatric and behavioral adverse reactions, including aggression, hostility, irritability, anger, and homicidal ideation and threats have been reported in patients taking perampanel. Monitor patients for these reactions as well as for changes in mood, behavior, or personality that are not typical for the patient, particularly during the titration period and at higher doses. Perampanel should be reduced if these symptoms occur and should be discontinued immediately if symptoms are severe or are worsening.

Side effects requiring immediate medical attention

Along with its needed effects, perampanel (the active ingredient contained in Fycompa) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking perampanel:

More common

  • Aggression or anger
  • anxiety
  • clumsiness or unsteadiness
  • deep or fast breathing with dizziness
  • dry mouth
  • irregular heartbeat
  • irritability
  • numbness of the feet, hands, and around the mouth
  • restlessness
  • shakiness
  • sleepiness or unusual drowsiness
  • trouble sleeping
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unsteady walk
  • unusual tiredness or weakness

Less common

  • Abnormal or decreased touch sensation
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings

Incidence not known

  • Changes in behavior
  • depression
  • thoughts of killing oneself

Side effects not requiring immediate medical attention

Some side effects of perampanel may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Dizziness or lightheadedness
  • feeling of constant movement of self or surroundings
  • headache
  • nausea
  • sensation of spinning
  • stomach pain

Less common

  • Back pain
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • blurred vision
  • body aches or pain
  • bone pain
  • changes in speech patterns
  • chills
  • confusion
  • cough
  • decreased urine output
  • difficulty having a bowel movement
  • difficulty with moving
  • double vision
  • ear congestion
  • fast or irregular heartbeat
  • fever
  • increased thirst
  • lack or loss of strength
  • loss of voice
  • muscle pain, cramps, or stiffness
  • nasal congestion
  • pain in the arms, joints, or legs
  • runny nose
  • slurred speech
  • sneezing
  • sore throat
  • trouble remembering
  • trouble with speaking
  • unusual weight gain or loss
  • unusually deep sleep
  • vomiting

Incidence not known

  • Unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

For Healthcare Professionals

Applies to perampanel: oral suspension, oral tablet


The more commonly reported adverse events have included dizziness, somnolence, fatigue, irritability, falls, nausea, weight gain, vertigo, and ataxia; in clinical trials, the highest dose (12 mg) resulted in greater reductions in seizure rates but with a substantial increase in adverse reactions.[Ref]

Nervous system

Very common (10% or more): Dizziness/vertigo (47%), somnolence (18%), gait disturbance (13%), headache (13%), irritability (12%)

Common (1% to 10%): Ataxia, dysarthria, gait disturbance, balance disorder, hypoesthesia, abnormal coordination, memory impairment, paresthesia[Ref]

Dizziness, somnolence, fatigue, and gait disturbance events appear to be dose-related and occurred mostly during the titration phase.[Ref]


Psychiatric and behavioral reactions appear to be dose-related, and typically appear early on in treatment (within the first 6 weeks, although have been reported 37 weeks out). Compared to placebo, patients treated with this drug experienced more hostility and aggression related events that were serious, severe, and led to dose reduction, interruption, and discontinuation. Homicidal ideation and/or threat were reported in 0.1% of the 4368 patients in controlled and open label trials (included some non-epilepsy trials). Patients with active psychotic disorders and unstable recurrent affective disorders were excluded from clinical trials.

Healthy volunteers taking this drug experienced paranoia, euphoric mood, agitation, anger, mental status changes, and disorientation/confusional state.[Ref]

Very common (10% or more): Hostility- and aggression-related reactions (20%), irritability (11%)

Common (1% to 10%): Anxiety, anger, hypersomnia, euphoric mood, disorientation/confusional state, altered mood

Uncommon (0.1% to 1%): Homicidal ideation and/or threat, suicidal ideation, suicide attempt

Frequency not reported: Belligerence, affect lability, agitation, physical assault, paranoia, changed mental status, delusions

Postmarketing reports: Acute psychosis, hallucinations, delirium, delusions, paranoia, confusional state, disorientation, memory impairment[Ref]


Very common (10% or more): Fatigue/asthenia/lethargy (15%), falls (10%), limb injury

Common (1% to 10%): Head injury, peripheral edema[Ref]


Common (1% to 10%): Contusion, skin laceration, rash

Postmarketing reports: Drug reaction with eosinophilia and systemic symptoms (DRESS)[Ref]


Common (1% to 10%): Nausea, vomiting, constipation, abdominal pain[Ref]


Common (1% to 10%): Weight gain, hyponatremia, decreased appetite, increased appetite

Frequency not reported: Increased triglycerides[Ref]

In adult trials, weight gain of at least 7% and 15% of baseline body weight occurred in 9.1% and 0.9% of treated patients compared to 4.5% and 0.2% of placebo-treated patients, respectively. Similar increases were observed in adolescents.[Ref]


Common (1% to 10%): Back pain, myalgia, pain in extremity, arthralgia, musculoskeletal pain, ligament sprain

Frequency not reported: Bone fractures[Ref]


Common (1% to 10%): Blurred vision, diplopia[Ref]


Common (1% to 10%): Cough, upper respiratory tract infection, oropharyngeal pain[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Fycompa (perampanel)." Eisai Inc (2012):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.