Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Zonegran
  2. Zonisade


Zonisamide is used together with other medicines to treat partial-onset seizures (convulsions) in the treatment of epilepsy. It acts on the central nervous system (CNS) to reduce the number and severity of seizures.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Capsule
  • Suspension

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of zonisamide in children younger than 16 years of age. Safety and efficacy have not been established.


Although appropriate studies on the relationship of age to the effects of zonisamide have not been performed in the geriatric population, geriatric-specific problems are not expected to limit the usefulness of zonisamide in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving zonisamide.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Methenamine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Calcifediol
  • Metformin
  • Methotrexate
  • Orlistat

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Aminolevulinic Acid
  • Ginkgo

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

  • Ethanol

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Allergy to sulfa drugs, history of—Should not be used in patients with this condition.
  • Blood or bone marrow problems (eg, agranulocytosis, aplastic anemia) or
  • Bone problems (eg, osteomalacia, osteopenia, osteoporosis) or
  • Depression, history of or
  • Mental illness (eg, psychosis) or
  • Metabolic acidosis (high acid in the blood)—Use with caution. May make these conditions worse.
  • Breathing or lung problems, severe or
  • Diarrhea or
  • Ketogenic diet, history of—Use with caution. May cause side effects to become worse.
  • Kidney disease or
  • Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper Use

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of side effects.

This medicine comes with a Medication Guide. Read and follow the instructions carefully. Ask your doctor if you have any questions.

You may take the medicine with or without food.

Swallow the capsule whole. Do not break, crush, or chew it.

Measure the oral liquid with a marked measuring spoon, oral syringe, or medicine cup. The average household teaspoon may not hold the right amount of liquid.

Drink extra water every day with this medicine to help prevent kidney stones.

This medicine will be used together with other seizure medicines. Keep using all of your medicines unless your doctor tells you to stop.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (capsules and suspension):
    • For seizures:
      • Adults and children 16 years of age and older—At first, 100 milligrams (mg) once a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 400 mg per day.
      • Children younger than 16 years of age—Use and dose must be determined by the doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Throw away any unused oral liquid 30 days after first opening the bottle.


It is very important that your doctor check your progress at regular visits to see if the medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine and for 1 month after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.

Check with your doctor right away if you have sudden back pain, abdominal or stomach pain, pain while urinating, or bloody or dark urine. These may be symptoms of kidney stones.

Serious skin reactions (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis) can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, chills, cough, diarrhea, itching, joint or muscle pain, red irritated eyes, red skin lesions, often with a purple center, sore throat, sores, ulcers, or white spots in the mouth or on the lips, or unusual tiredness or weakness.

This medicine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. If you can, avoid people with infections. Check with your doctor right away if you think you are getting an infection, or if you have a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

Zonisamide may cause serious allergic reaction called drug reaction with eosinophilia and systemic symptoms (DRESS), which can be life-threatening and requires immediate medical attention. Check with your doctor right away if you have black, tarry stools, chest pain, chills, cough, fever, painful or difficult urination, sore throat, sores, ulcers, or white spots on the lips or in the mouth, swollen glands, trouble breathing, or unusual bleeding or bruising.

This medicine may make you sweat less, which causes your body temperature to increase. Use extra care not to become overheated during exercise or hot weather while you are taking this medicine. Overheating may result in heat stroke. Also, hot baths or saunas may make you dizzy or faint while you are taking this medicine.

Check with your doctor right away if eye pain or redness, blurred vision, difficulty with reading, or any other change in vision occurs during or after treatment. These could be symptoms of serious eye or vision problems (eg, acute myopia, secondary angle closure glaucoma). Your doctor may want your eyes be checked by an ophthalmologist (eye doctor).

Call your doctor right away if you have fast breathing, loss of appetite, fast, pounding, or uneven heartbeats, or unusual tiredness or weakness. These may be symptoms of a condition called metabolic acidosis.

This medicine may cause slow growth. If your child is using this medicine, the doctor will need to keep track of your child's height and weight to make sure that your child is growing properly.

Zonisamide may cause hyperammonemia (too much ammonia in the blood), which may damage the brain and can be life-threatening. Check with your doctor right away if you have nausea or vomiting that continues, an increase in the frequency of seizures, loss of appetite, swelling of the face, tiredness and weakness, or yellow eyes or skin.

Do not stop taking zonisamide without first checking with your doctor. Stopping the medicine suddenly may cause your seizures to return or to occur more often. Your doctor may want you to gradually reduce the amount of medicine you are taking before stopping it completely.

This medicine may cause some people to become dizzy, drowsy, or less alert than normal. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines, medicine for allergies or colds, sedatives, tranquilizers, sleeping medicine, prescription pain medicine, narcotics, medicine for seizures, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor or dentist before taking any of the above while you are taking this medicine.

Some women who use this medicine have become infertile (unable to have children). Talk with your doctor before using this medicine if you plan to have children.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines, and herbal or vitamin supplements.

Side Effects

Along with its needed effects, a medicine 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:

More common

  1. Blindness
  2. blurred vision
  3. decreased vision
  4. discouragement
  5. double vision
  6. eye pain
  7. fast, irregular, pounding, or racing heartbeat or pulse
  8. feeling sad or empty
  9. headache
  10. irritability
  11. lack of appetite
  12. loss of interest or pleasure
  13. mood or mental changes
  14. shakiness or unsteady walking
  15. tearing
  16. tiredness
  17. trouble concentrating
  18. trouble sleeping

Less common

  1. Agitation
  2. black, tarry stools
  3. bruising
  4. changes in skin color
  5. chest pain
  6. chills
  7. confusion
  8. cough
  9. delusions
  10. dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  11. fever
  12. hallucinations
  13. large, flat blue or purplish patches on the skin
  14. nervousness
  15. pain, tenderness, or swelling of the foot or leg
  16. painful or difficult urination
  17. pale skin
  18. pounding in the ears
  19. rash
  20. slow or fast heartbeat
  21. sore throat
  22. sores, ulcers, or white spots on the lips or in the mouth
  23. sweating
  24. swollen glands
  25. unusual bleeding or bruising
  26. unusual tiredness or weakness


  1. Anxiety
  2. chest tightness
  3. clay-colored stools
  4. coma
  5. dark urine
  6. decreased urine output
  7. diarrhea
  8. dilated neck veins
  9. indigestion
  10. irregular breathing
  11. irregular heartbeat
  12. small, red or purple spots on the skin
  13. stiff neck
  14. stomach pain and cramps
  15. swelling of the face, fingers, feet, or lower legs
  16. trouble breathing
  17. twitching, twisting, uncontrolled repetitive movements of the tongue, lips, face, arms, or legs
  18. unpleasant breath odor
  19. vomiting of blood
  20. watery or bloody diarrhea
  21. weight gain
  22. yellow eyes or skin

Incidence not known

  1. Change in near or distance vision
  2. difficulty in focusing eyes
  3. increase in frequency of seizures
  4. swelling of the face

Some side effects 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

  1. Continuing ringing or buzzing or other unexplained noise in ears
  2. diarrhea
  3. difficulty with memory
  4. dizziness
  5. hearing loss
  6. loss of appetite
  7. nausea
  8. restlessness
  9. sleepiness
  10. unusual drowsiness

Less common

  1. Acid or sour stomach
  2. bad, unusual, or unpleasant taste in the mouth
  3. belching
  4. bleeding gums
  5. change in taste
  6. constipation
  7. decreased interest in sexual intercourse
  8. difficulty with speaking
  9. difficulty with thinking
  10. dry mouth
  11. general ill feeling
  12. headache
  13. heartburn
  14. inability to have or keep an erection
  15. increased hair growth, especially on the face
  16. irritation in the mouth
  17. loss in sexual ability, desire, drive, or performance
  18. loss of strength or energy
  19. mental slowness
  20. mouth ulcers
  21. muscle or joint pain
  22. redness and swelling of the gums
  23. runny or stuffy nose
  24. sneezing
  25. tingling, burning, or prickly feelings on the skin
  26. uncontrolled, back and forth, or rolling eye movements
  27. weight loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.