Felbatol Side Effects

Generic name: felbamate

Medically reviewed by Drugs.com. Last updated on Feb 28, 2025.

Note: This document provides detailed information about Felbatol Side Effects associated with felbamate. Some dosage forms listed on this page may not apply specifically to the brand name Felbatol.

Applies to felbamate: oral suspension, oral tablet.

Important warnings This medicine can cause some serious health issues

Oral route (tablet; suspension)

Felbamate use is associated with a marked increase in the incidence of aplastic anemia, sometimes fatal.

Discontinue if any evidence of bone marrow depression occurs.

Liver failure resulting in death or transplant has been reported with therapy.

Felbamate should not be prescribed for anyone with a history of hepatic dysfunction and should be discontinued in anyone showing signs of liver injury while on therapy.

Monitor liver enzymes during therapy.

Serious side effects of Felbatol

Along with its needed effects, felbamate (the active ingredient contained in Felbatol) 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 side effects

• 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 side effects

• 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 side effects

• 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

Other side effects of Felbatol

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 side effects

• 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 side effects

• 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 adverse events

• Very common (10% or more): Headache (36.8%), somnolence (19.3%), dizziness (18.4%)
• Common (1% to 10%): Tremor, abnormal gait, paresthesia, ataxia
• Uncommon (0.1% to 1%): Migraine
• Postmarketing reports: Hyperpyrexia, paralysis, mononeuritis^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (34.2%), vomiting (16.7%), dyspepsia (12.3%), constipation (11.4%)
• Common (1% to 10%): Diarrhea, dry mouth, abdominal pain, hiccough
• Uncommon (0.1% to 1%): Esophagitis
• Postmarketing reports: GI hemorrhage, pancreatitis, hematemesis, gastritis, rectal hemorrhage, flatulence, gingival bleeding, acquired megacolon, ileus, intestinal obstruction, enteritis, ulcerative stomatitis, glossitis, dysphagia, jaundice, gastric ulcer, gastric dilatation, gastroesophageal reflux^[Ref]

Hepatic

• Common (1% to 10%): Serum glutamic-pyruvic transaminase (SGPT) increased
• Postmarketing reports: Hepatitis, hepatic failure, hepatorenal syndrome^[Ref]

Dermatologic

• Common (1% to 10%): Acne, rash, pruritus
• Uncommon (0.1% to 1%): Urticaria, bullous eruption
• Rare (less than 0.1%): Buccal mucous membrane swelling, Stevens-Johnson Syndrome, photosensitivity
• Postmarketing reports: Abnormal body odor, sweating, lichen planus, livedo reticularis, alopecia, toxic epidermal necrolysis (TEN)^[Ref]

Metabolic

• Very common (10% or more): Anorexia (19.3%)
• Common (1% to 10%): Weight loss, weight gain, hypophosphatemia
• Uncommon (0.1% to 1%): Increased appetite, hypokalemia, hyponatremia, LDH increased, alkaline phosphatase increased
• Rare (less than 0.1%): Creatinine phosphokinase increased
• Postmarketing reports: Hyperammonemia, hypernatremia, hypoglycemia, SIADH, hypomagnesemia, dehydration, hyperglycemia, hypocalcemia^[Ref]

Hematologic

• Very common (10% or more): Purpura (12.9%)
• Common (1% to 10%): Leukopenia
• Uncommon (0.1% to 1%): Leukocytosis, thrombocytopenia, granulocytopenia
• Rare (less than 0.1%): Antinuclear factor test positive, qualitative platelet disorder, agranulocytosis
• Postmarketing reports: Sepsis, increased and decreased prothrombin time, anemia, hypochromic anemia, aplastic anemia, pancytopenia, hemolytic uremic syndrome, increased mean corpuscular volume with and without anemia, coagulation disorder, embolism-limb, disseminated intravascular coagulation, eosinophilia, hemolytic anemia, leukemia, including myelogenous leukemia, and lymphoma, including T-cell and B-cell lymphoproliferative disorders^[Ref]

Genitourinary

• Common (1% to 10%): Intramenstrual bleeding, urinary tract infection, urinary incontinence
• Frequency not reported: Menstrual disorder, hematuria, urinary retention, vaginal hemorrhage, dysuria^[Ref]

Hypersensitivity

• Rare (less than 0.1%): Anaphylactoid reaction^[Ref]

Cardiovascular

• Common (1% to 10%): Palpitation, tachycardia
• Uncommon (0.1% to 1%): Lymphadenopathy
• Rare (less than 0.1%): Supraventricular tachycardia
• Postmarketing reports: Atrial fibrillation, atrial arrhythmia, cardiac arrest, torsade de pointes, cardiac failure, hypotension, hypertension, flushing, thrombophlebitis, ischemic necrosis, gangrene, peripheral ischemia, bradycardia, Henoch-Schonlein purpura (vasculitis), cerebrovascular disorder, cerebral edema^[Ref]

Immunologic

• Common (1% to 10%): Influenza-like symptoms
• Postmarketing reports: Lupus syndrome^[Ref]

Musculoskeletal

• Common (1% to 10%): Myalgia
• Uncommon (0.1% to 1%): Dystonia
• Postmarketing reports: Rigors, arthralgia, muscle weakness, involuntary muscle contraction, rhabdomyolysis^[Ref]

Ocular

• Common (1% to 10%): Diplopia, abnormal vision, miosis
• Postmarketing reports: Nystagmus, hemianopsia, conjunctivitis^[Ref]

Oncologic

• Postmarketing reports: Neoplasm^[Ref]

Other

• Very common (10% or more): Fever (22.6%), fatigue (16.8%)
• Common (1% to 10%): Otitis media, face edema, depression, taste perversion, pain, asthenia, malaise
• Postmarketing reports: Edema, sudden death, hypothermia, fetal death, microcephaly, genital malformation, anencephaly, encephalocele, decreased hearing, placental disorder^[Ref]

Psychiatric

• Very common (10% or more): Insomnia (17.5%)
• Common (1% to 10%): Anxiety, nervousness, stupor, abnormal thinking, emotional lability, agitation, psychological disturbance, aggressive reaction
• Uncommon (0.1% to 1%): Hallucination, euphoria, suicide attempt
• Postmarketing reports: Delusion, manic reaction, paranoid reaction, confusion, psychosis, apathy, impaired concentration^[Ref]

Renal

• Postmarketing reports: Acute renal failure, nephrosis, abnormal renal function^[Ref]

Respiratory

• Common (1% to 10%): Upper respiratory tract infection, rhinitis, chest pain, sinusitis, pharyngitis, coughing
• Postmarketing reports: Respiratory depression^[Ref]

Further information

Felbatol side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer