Skip to Content

Felbatol Side Effects

Generic Name: felbamate

Note: This page contains information about the side effects of felbamate. Some of the dosage forms included on this document may not apply to the brand name Felbatol.

In Summary

Common side effects of Felbatol include: headache, nausea, vomiting, constipation, insomnia, and anorexia. Other side effects include: abdominal pain, abnormal gait, depression, diplopia, nervousness, tremor, and dysgeusia. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to felbamate: oral suspension, oral tablet

In addition to its needed effects, some unwanted effects may be caused by felbamate (the active ingredient contained in Felbatol). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when 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
  • 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

Minor Side Effects

Some of the side effects that can occur with felbamate may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

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

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]


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]


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


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]


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]


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]


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


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


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]


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


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


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


Postmarketing reports: Neoplasm[Ref]


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]


Very common (10% or more): Insomnia (17.5%)
Common (1% to 10%): Anxiety, nervousness, stupor, abnormal thinking, emotional liability, 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]


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


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


1. "Product Information. Felbamate (felbamate)." Amneal Pharmaceuticals, Glasgow, KY.

Not all side effects for Felbatol may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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. 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.