Felbamate Side Effects

Some side effects of felbamate may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to felbamate: oral suspension, oral tablet

Along with its needed effects, felbamate 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 felbamate:

More common
  • Black, tarry stools
  • chest pain
  • chills
  • confusion
  • cough
  • delusions
  • dementia
  • depression
  • fever
  • loss of bladder control
  • painful or difficult urination
  • purple or red spots on the skin
  • shakiness in the legs, arms, hands, or feet
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • trembling or shaking of the hands or feet
  • unusual bleeding or bruising
  • unusual tiredness or weakness
Less common
  • Agitation, aggression, or other mood or mental changes
  • bladder pain
  • bloody or cloudy urine
  • bone pain
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • clumsiness or unsteadiness
  • frequent urge to urinate
  • loss of appetite
  • lower back or side pain
  • skin rash
  • swelling or puffiness of the face
  • trouble with breathing
  • unsteadiness, trembling, or other problems with muscle control or coordination
Rare
  • Continuing headache
  • continuing stomach pain
  • continuing vomiting
  • dark-colored urine
  • general feeling of tiredness or weakness
  • hives or itching
  • light-colored stools
  • muscle cramps
  • nasal congestion
  • nosebleeds or other unusual bruising or bleeding
  • pain
  • sensitivity of the skin to sunlight
  • swollen or painful glands
  • tightness in the chest
  • yellow eyes or skin

Some side effects of felbamate 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
  • Acid or sour stomach
  • bad, unusual, or unpleasant (after) taste
  • belching
  • body aches or pain
  • change in taste
  • change in walking and balance
  • constricted, pinpoint, or small pupils (black part of the eye)
  • crying
  • depersonalization
  • diarrhea
  • difficulty having a bowel movement (stool)
  • difficulty with sleeping
  • dizziness
  • double vision
  • dysphoria
  • ear congestion
  • euphoria
  • headache
  • heartburn
  • hiccup
  • indigestion
  • loss of appetite
  • loss of voice
  • nausea
  • paranoia
  • quick to react or overreact emotionally
  • rapidly changing moods
  • runny nose
  • seeing double
  • sleepiness or unusual drowsiness
  • sleeplessness
  • sneezing
  • stomach discomfort, upset, or pain
  • trouble sleeping
  • unable to sleep
  • weight loss
Less common
  • Blemishes on the skin
  • blurred vision
  • decreased awareness or responsiveness
  • decreased weight
  • difficulty with moving
  • earache
  • hoarseness
  • joint pain
  • muscle aching or cramping
  • muscle pains or stiffness
  • pain or tenderness around the eyes and cheekbones
  • pimples
  • redness or swelling in the ear
  • severe sleepiness
  • swollen joints
  • tender, swollen glands in the neck
  • trouble with swallowing
  • voice changes

For Healthcare Professionals

Applies to felbamate: oral suspension, oral tablet

Nervous system

In controlled trials with felbamate as monotherapy, no nervous system effect occurred with a frequency greater than 7%. However, the frequency of nervous system effects (particularly sedative effects) was much greater in controlled studies of felbamate as adjuvant therapy with other antiepileptic agents. Ataxia, tremor, involuntary movements, psychosis, and blurred vision have also been reported rarely.

One prospective investigation found 20 of 60 (33%) epileptic patients to have reported a headache. The headache was pounding in 11 patients, steady in 9 patients, and moderate or severe in 19 patients. Patients who had the headaches reported that they occurred at least once a week.

Nervous system side effects are common and include insomnia, headache, anxiety, dizziness, somnolence, fatigue, and lethargy.

Gastrointestinal

Gastrointestinal side effects are common and include nausea, vomiting, dyspepsia, constipation, diarrhea, and bad taste in mouth. Some clinicians have reported that anorexia and weight loss occur commonly.

Dyspepsia and vomiting occur in as many as 9% of treated patients.

Hepatic

Hepatic side effects include mild elevations of liver function tests which occur in as many as 5% of treated patients. The manufacturer reports that several cases of acute liver failure have also occurred in patients taking felbamate. A case of massive acute hepatic necrosis and death within 40 days of initiation of felbamate therapy has also been reported.

Dermatologic

Dermatologic side effects including rashes and acne occur in approximately 3% of treated patients. The Stevens-Johnson syndrome has been reported rarely. A case of toxic epidermal necrolysis has also been reported.

Metabolic

Metabolic side effects including hypophosphatemia have been reported in approximately 3% of treated patients.

Hematologic

Hematologic side effects include leukopenia, thrombocytopenia, and agranulocytosis rarely. Nine cases of aplastic anemia have been reported in the United States from the time of commercial release of felbamate to August 1, 1994.

Genitourinary

Genitourinary side effects including a case of urolithiasis have been reported.

Hypersensitivity

Hypersensitivity side effects including a case of felbamate induced delayed anaphylaxis have been reported.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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