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Last reviewed on RxList: 3/13/2018
Zonegran Side Effects Center

Last reviewed on RxList 3/13/2018

Zonegran (zonisamide) is a sulfonamide anticonvulsant and a carbonic anhydrase inhibitor indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy. Common side effects of Zonegran include:

Tell the doctor immediately if you notice serious side effects of Zonegran including increased or worsening seizures, lightheadedness, shortness of breath, rapid heart rate, trouble concentrating, fever, chills, sores in your mouth and throat, severe pain in your lower back, blood in your urine, feeling very thirsty or hot, being unable to urinate, or severe skin reaction.

The dose of Zonegran is 25 mg or 100 mg capsules administered orally once or twice daily. Zonegran may interact with other medicines that make you sleepy (such as cold or allergy medicines, sedatives, narcotics, sleeping pills, muscle relaxers, and medicines for depression or anxiety), carbamazepine phenobarbital, phenytoin, topiramate, or cold or allergy medicines that contain antihistamines. Tell your doctor all medications and supplements you use. Zonegran is not recommended during pregnancy; it could harm a fetus. Talk to your doctor about using birth control, and tell your doctor if you become pregnant during treatment with Zonegran. Zonegran passes into breast milk and may harm a nursing baby. Breastfeeding while using Zonegran is not recommended.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Zonegran Consumer Information

Get emergency medical help if you have signs of an allergic reaction: any form of skin rash, hives; fever, swollen glands, feeling weak or tired, severe muscle pain, unusual bruising or bleeding; yellowing of your skin or the whites of your eyes; difficult breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: sudden mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

  • decreased sweating, feeling very hot;
  • symptoms of metabolic acidosis--loss of appetite, feeling tired, problems with thinking or talking, irregular heartbeats;
  • symptoms of a blood cell disorder--fever, chills, body aches, flu symptoms, sores in your mouth and throat;
  • symptoms of a kidney stone--severe pain in your stomach or lower back, blood in your urine;
  • increased or worsening seizures;
  • the first sign of any skin rash, no matter how mild; or
  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • drowsiness, dizziness;
  • problems with memory or concentration;
  • feeling agitated or irritable;
  • loss of coordination, trouble walking; or
  • loss of appetite.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Zonegran (Zonisamide)

Zonegran Professional Information


The most common adverse reactions with ZONEGRAN (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in descending order of frequency were somnolence, anorexia, dizziness, ataxia, agitation/irritability, and difficulty with memory and/or concentration.

In controlled clinical trials, 12% of patients receiving ZONEGRAN as adjunctive therapy discontinued due to an adverse reaction compared to 6% receiving placebo. Approximately 21% of the 1,336 patients with epilepsy who received ZONEGRAN in clinical studies discontinued treatment because of an adverse reaction. The most common adverse reactions leading to discontinuation were somnolence, fatigue and/or ataxia (6%), anorexia (3%), difficulty concentrating (2%), difficulty with memory, mental slowing, nausea/vomiting (2%), and weight loss (1%). Many of these adverse reactions were doserelated (see WARNINGS and PRECAUTIONS).

Adverse Reaction Incidence In Controlled Clinical Trials

Table 4 lists adverse reactions that occurred in at least 2% of patients treated with ZONEGRAN in controlled clinical trials that were numerically more common in the ZONEGRAN group. In these studies, either ZONEGRAN or placebo was added to the patient's current AED therapy.

Table 4. Adverse Reactions in Placebo-Controlled, Add-On Trials (Events that occurred in at least 2% of ZONEGRANtreated patients and occurred more frequently in ZONEGRAN-treated than placebo-treated patients)

ZONEGRAN (n=269)
PLACEBO (n=230)
  Headache 10 8
  Abdominal Pain 6 3
  Flu Syndrome 4 3
  Anorexia 13 6
  Nausea 9 6
  Diarrhea 5 2
  Dyspepsia 3 1
  Constipation 2 1
  Dry Mouth 2 1
  Ecchymosis 2 1
  Weight Loss 3 2
  Dizziness 13 7
  Ataxia 6 1
  Nystagmus 4 2
  Paresthesia 4 1
  Confusion 6 3
  Difficulty Concentrating 6 2
  Difficulty with Memory 6 2
  Mental Slowing 4 2
  Agitation/Irritability 9 4
  Depression 6 3
  Insomnia 6 3
  Anxiety 3 2
  Nervousness 2 1
  Schizophrenic/Schizophreniform Behavior 2 0
  Somnolence 17 7
  Fatigue 8 6
  Tiredness 7 5
  Speech Abnormalities 5 2
  Difficulties in Verbal Expression 2 <1
  Rhinitis 2 1
  Rash 3 2
  Diplopia 6 3
  Taste Perversion 2 0

Other Adverse Reactions In Clinical Trials

ZONEGRAN has been administered to 1,598 individuals during all clinical trials, only some of which were placebo-controlled. The frequencies represent the proportion of the 1,598 individuals exposed to ZONEGRAN who experienced an event on at least one occasion. All events are included except those already listed in the previous table or discussed in WARNINGS or PRECAUTIONS, trivial events, those too general to be informative, and those not reasonably associated with ZONEGRAN.

Events are further classified within each category and listed in order of decreasing frequency as follows: frequent occurring in at least 1:100 patients; infrequent occurring in 1:100 to 1:1000 patients; rare occurring in fewer than 1:1000 patients.

Body As A Whole

Frequent: Accidental injury, asthenia. Infrequent: Chest pain, flank pain, malaise, allergic reaction, face edema, neck rigidity. Rare: Lupus erythematosus.


Infrequent: Palpitation, tachycardia, vascular insufficiency, hypotension, hypertension, thrombophlebitis, syncope, bradycardia. Rare: Atrial fibrillation, heart failure, pulmonary embolus, ventricular extrasystoles.


Frequent: Vomiting. Infrequent: Flatulence, gingivitis, gum hyperplasia, gastritis, gastroenteritis, stomatitis, cholelithiasis, glossitis, melena, rectal hemorrhage, ulcerative stomatitis, gastro-duodenal ulcer, dysphagia, gum hemorrhage. Rare: Cholangitis, hematemesis, cholecystitis, cholestatic jaundice, colitis, duodenitis, esophagitis, fecal incontinence, mouth ulceration.

Hematologic And Lymphatic

Infrequent: Leukopenia, anemia, immunodeficiency, lymphadenopathy. Rare: Thrombocytopenia, microcytic anemia, petechia.

Metabolic And Nutritional

Infrequent: Peripheral edema, weight gain, edema, thirst, dehydration. Rare: Hypoglycemia, hyponatremia, lactic dehydrogenase increased, SGOT increased, SGPT increased.


Infrequent: Leg cramps, myalgia, myasthenia, arthralgia, arthritis.

Nervous System

Frequent: Tremor, convulsion, abnormal gait, hyperesthesia, incoordination. Infrequent: Hypertonia, twitching, abnormal dreams, vertigo, libido decreased, neuropathy, hyperkinesia, movement disorder, dysarthria, cerebrovascular accident, hypotonia, peripheral neuritis, reflexes increased. Rare: Dyskinesia, dystonia, encephalopathy, facial paralysis, hypokinesia, hyperesthesia, myoclonus, oculogyric crisis.

Behavioral Abnormalities –Non-Psychosis -Related

Infrequent: Euphoria.


Frequent: Pharyngitis, cough increased. Infrequent: Dyspnea. Rare: Apnea, hemoptysis.

Skin And Appendages

Frequent: Pruritus. Infrequent: Maculopapular rash, acne, alopecia, dry skin, sweating, eczema, urticaria, hirsutism, pustular rash, vesiculobullous rash.

Special Senses

Frequent: Amblyopia, tinnitus. Infrequent: Conjunctivitis, parosmia, deafness, visual field defect, glaucoma. Rare: Photophobia, iritis.


Infrequent: Urinary frequency, dysuria, urinary incontinence, hematuria, impotence, urinary retention, urinary urgency, amenorrhea, polyuria, nocturia. Rare: Albuminuria, enuresis, bladder pain, bladder calculus, gynecomastia, mastitis, menorrhagia.

Post Marketing Experience

The following serious adverse reactions have been reported since approval and use of ZONEGRAN worldwide. These reactions are reported voluntarily from a population of uncertain size; therefore, it is not possible to estimate their frequency or establish a causal relationship to drug exposure.

Acute pancreatitis, rhabdomyolysis, increased creatine phosphokinase, and drug reaction with eosinophilia and systemic symptoms (DRESS) (see WARNINGS).

To report SUSPECTED ADVERSE REACTIONS, contact Concordia Pharmaceuticals Inc. at 1- 877-370-1142 or the FDA at 1-800-FDA-1088 or

Read the entire FDA prescribing information for Zonegran (Zonisamide)

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© Zonegran Patient Information is supplied by Cerner Multum, Inc. and Zonegran Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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