Zonegran (Zonisamide) – Oral

Warning:

Potentially Fatal Reactions to Sulfonamides: If you’re hypersensitive or allergic to sulfonamides (zonisamide is a sulfonamide), avoid using Zonegran.


Fetal Harm (Teratogenicity): Zonegran during pregnancy may harm your fetus. If you’re able to have children and are on Zonegran, it’s strongly advised to use effective contraception. Fetal abnormalities (e.g., heart defects and embryo-fetal deaths) have occurred while using Zonegran. Zonisamide should be used during pregnancy only if the potential benefit justifies the potential risk to your fetus.

What Is Zonegran?

Zonegran (zonisamide) is a prescription anticonvulsant (anti-epilepsy drug, or AED) used to prevent seizures for adults and teenagers aged 16 and older who have certain types of epilepsy. It comes in capsule form and is taken by mouth (orally). Zonegran prevents nerve overactivity in the brain by acting on the nerve’s sodium and calcium channels. Zonegran is classified as a sulfonamide and a carbonic anhydrase inhibitor.

Drug Facts

Generic Name: Zonisamide

Brand Name(s): Zonegran

Drug Availability: Prescription

Therapeutic Classification: Anticonvulsant

Available Generically: Yes

Controlled Substance: N/A

Administration Route: Oral

Active Ingredient: Zonisamide

Dosage Form(s): Capsule

What is Zonegran Used For?

Zonegran (zonisamide) is approved as an extra (adjunctive) treatment for preventing partial seizures. Preventing seizures that occur due to epilepsy may reduce injury and other seizure complications.

Partial seizures are seizures that begin with abnormal electrical activity in one area of the brain. They can be brief and may only affect a small region of the brain, with limited effects and may include symptoms like unusual sensations, or jerking or stiffness of one part of the body. Partial seizures can also spread to both sides of the brain, with an altered level of consciousness, and sometimes with more noticeable physical symptoms. 

A partial seizure usually lasts for a few minutes. You can have some residual effects after a partial seizure, and these can include weakness or paralysis of the area of the body that’s associated with where the seizure started in the brain. 

“Adjunctive epilepsy treatment” is an AED medicine prescribed with other AED medicines to prevent seizures, rather than on its own. Adjunctive seizure therapies usually work together and in slightly different ways, to prevent seizures.

How to Take Zonegran

You should take Zonegran as prescribed by your healthcare provider. This medication can be taken with or without food and the capsules should be swallowed whole.

Storage

Zonegran should be stored in its original container away from moisture and light. It should be kept away from the reach of children and pets. 

Store Zonegran at a temperature of 77 degrees Fahrenheit. When out of the home, it’s OK to briefly store in temperatures between 59 and 86 degrees.

Off-Label Uses

In addition to its approved indications, Zonegran is sometimes prescribed off-label for treatment of other medical conditions. 

Some of the off-label conditions that Zonegran may be prescribed for include:

Your healthcare provider can discuss instructions with you about how to take Zonegran if you’re using it for an off-label indication. Your dosage may be different from the dosage that’s prescribed for epilepsy treatment.

How Long Does Zonegran Take to Work?

This medication should start having effects within a few hours, but you may not experience the full effects of seizure prevention until you have been regularly taking it as prescribed for several days.

What Are the Side Effects of Zonegran?

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Zonegran (zonisamide) can cause side effects. The side effects are more likely at higher doses, but side effects are possible even at low doses and when it’s taken as prescribed.

Common Side Effects

The most common side effects of Zonegran are:

  • Double vision
  • Extreme tiredness
  • Lack of appetite
  • Dizziness
  • Diminished balance
  • Agitation or irritability
  • Difficulty with memory and/or concentration

These common side effects can be mild, tolerable, and temporary but can still be distressing for some people. Talk with your healthcare provider about any side effects that are bothersome for you. You may need a change in your medication or treatment for your side effects.

Severe Side Effects

Zonegran can cause serious side effects that may be dangerous. While these adverse reactions are not common, it’s important that you learn to recognize them so you can get medical treatment promptly if you need it. 

Severe side effects of Zonegran include but are not limited to:

  • Severe skin reactions
  • Bleeding, bruising
  • Organ damage from drug reaction with eosinophilia and systemic symptoms (DRESS)
  • Sudden vision changes like quick onset nearsightedness (acute myopia) and changes in the eye’s angle (secondary angle closure glaucoma)
  • Suicidal thoughts or behavior
  • Decreased sweating (oligohidrosis) in pediatric patients leading to heat stroke and hospitalization
  • Drops in bicarbonate levels in the body (hyperchloremic, non-anion gap, metabolic acidosis)
  • Fetal abnormalities (e.g., heart defects and embryo-fetal deaths) during pregnancy
  • High blood levels of ammonia (hyperammonemia) and change in brain function or structure (encephalopathy) 

If you or someone you know has any of these reactions, seek immediate medical attention.

Long-Term Side Effects

Zonegran can cause weight gain for some people when it’s used for a long period of time.

Report Side Effects

Zonegran may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Zonegran Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose medicines in this class 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 these medicines. 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 sulfadiazine
  • For oral dosage form (tablet):
    • For bacterial or protozoal infections:
      • Adults and teenagers—2 to 4 grams for the first dose, then 1 gram every four to six hours.
      • Children 2 months of age and older—Dose is based on body weight. The usual dose is 75 milligrams (mg) per kilogram (kg) (34 mg per pound) of body weight for the first dose, then 37.5 mg per kg (17 mg per pound) of body weight every six hours, or 25 mg per kg (11.4 mg per pound) of body weight every four hours.
      • Children up to 2 months of age—Use is not recommended.
    For sulfamethizole
  • For oral dosage form (tablets):
    • For bacterial infections:
      • Adults and teenagers—500 milligrams (mg) to 1 gram every six to eight hours.
      • Children 2 months of age and older—Dose is based on body weight. The usual dose is 7.5 to 11.25 mg per kilogram (kg) (3.4 to 5.1 mg per pound) of body weight every six hours.
      • Children up to 2 months of age—Use is not recommended.
    For sulfamethoxazole
  • For oral dosage form (tablets):
    • For bacterial or protozoal infections:
      • Adults and teenagers—2 to 4 grams for the first dose, then 1 to 2 grams every eight to twelve hours.
      • Children 2 months of age and older—Dose is based on body weight. The usual dose is 50 to 60 milligrams (mg) per kilogram (kg) (22.7 to 27.3 mg per pound) of body weight for the first dose, then 25 to 30 mg per kg (11.4 to 13.6 mg per pound) of body weight every twelve hours.
      • Children up to 2 months of age—Use and dose must be determined by your doctor.
    For sulfisoxazole
  • For oral dosage forms (suspension, syrup, or tablets):
      • Adults and teenagers—2 to 4 grams for the first dose, then 750 milligrams (mg) to 1.5 grams every four hours; or 1 to 2 grams every six hours.
      • Children 2 months of age and older—Dose is based on body weight. The usual dose is 75 mg per kilogram (kg) (34 mg per pound) of body weight for the first dose, then 25 mg per kg (11.4 mg per pound) of body weight every four hours, or 37.5 mg per kg (17 mg per pound) of body weight every six hours.
      • Children up to 2 months of age—Use and dose must be determined by your doctor.

Modifications

Take Zonegran as prescribed by your healthcare provider. Ask your prescriber or pharmacist for tips on how to manage taking your medicine.

Missed Dose

Missing a dose of an anti-epilepsy drug (AED) can be a reason for breakthrough seizures. Try to do your best to remember to take your medicine as prescribed.

Overdose: What Happens If I Take Too Much Zonegran?

Taking too much Zonegran can be dangerous. Call your healthcare provider if you take too much Zonegran and get urgent medical attention if you begin to have symptoms of an overdose. 

Effects of Zonegran overdose can include the following, and may be fatal if untreated: 

  • Deceased heart rate (bradycardia)
  • Low blood pressure (hypotension)
  • Slow and/or shallow breathing 

Management of an overdose can include close observation, treatment of symptoms, or removal of the drug from the body with medically induced vomiting or direct removal from the stomach and esophagus through a tube.

What Happens If I Use Too Much Zonegran?

If you think you or someone else may have overdosed on Zonegran, call a healthcare provider or the Poison Control Center (800-222-1222).
If someone collapses or isn't breathing after taking Zonegran, call 911 immediately.

Precautions

Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits. This medicine may cause blood problems, especially if it is taken for a long time.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Sulfonamides may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.

Sulfonamides may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:

  • Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
  • Wear protective clothing, including a hat. Also, wear sunglasses.
  • Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
  • Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
  • Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

This medicine may also cause some people to become dizzy. 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 are not alert. If this reaction is especially bothersome, check with your doctor.

What Are Reasons I Shouldn’t Take Zonegran?

Children

Zonegran has been associated with a decrease in sweating (oligohidrosis) in children (0–18 years of age). This is dangerous because it can cause heat stroke, which may require hospitalization. Pay close attention to any of these symptoms in your child and work with your healthcare provider if you notice any changes.

Pregnancy

Zonegran during pregnancy may present a serious risk to your fetus. If you’re able to have children and are on Zonegran, it’s strongly advised to use effective contraception. Fetal abnormalities (ex., heart defects and embryo-fetal deaths) have occurred while using Zonegran. Zonisamide should be used during pregnancy only if the potential benefit justifies the potential risk to your fetus.

Medications

Zonegran can cause bicarbonate levels to drop in the body (hyperchloremic, non-anion gap, metabolic acidosis). It’s important to talk with your healthcare provider about any conditions you have or other drugs or supplements that you use to see if they may increase your risk of acidosis (for example, diarrhea, epilepsy, ketogenic diet, renal disease, severe respiratory disorders, or drugs like acetazolamide, biguanides, cholestyramine, polyhydric sugars, salicylates, sevelamer hydrochloride, other sulfonamides or sulfa derivatives). These could all add to Zonegran’s bicarbonate-lowering effects.

What Other Medications Interact With Zonegran?

Zonegran is an adjunctive anticonvulsant (anti-epilepsy drug (AED)) that is typically prescribed for use with one or more AEDs. This medication does not cause harmful interactions with carbamazepine, lamotrigine, phenytoin, or sodium valproate.

  • Other carbonic anhydrase inhibitors: Using Zonegran with topiramate, acetazolamide or dichlorphenamide, may increase the risk of kidney stones, high ammonia levels, or metabolic acidosis.
  • Other drugs that increase risk of acidosis (ex., drugs like acetazolamide, biguanides, cholestyramine, polyhydric sugars, salicylates, sevelamer hydrochloride): Zonegran can cause metabolic acidosis. It should be used with caution in combination with other drugs that may cause metabolic acidosis.
  • Other sulfonamides: Using Zonegran with sulfonamides can cause Stevens-Johnson syndrome (a rare but serious skin and mucous membrane disease), toxic epidermal necrolysis (skin disorder where the skin blisters and peels), fulminant hepatic necrosis (severe, acute liver failure with no prior diagnosis of liver disease), agranulocytosis (rare, drug-induced blood disorder with a severe drop in white blood cells), aplastic anemia (rare disease where the body doesn’t make enough new blood cells), and other blood complications.
  • CYP3A4 inducers: When medications that induce liver enzymes, such as Rifadin (rifampicin), are used with Zonegran, the interaction can change the levels of Zonegran in the body. Individuals should be closely monitored and the Zonegran dosage adjusted with other CYP3A4 inducers. 
  • Central nervous system (CNS) depressants: Zonegran can cause CNS depression, and other cognitive and/or psychiatric effects. It should be used with caution in combination with alcohol or other CNS depressants.
  • Diets that increase risk of acidosis: Zonegran can cause metabolic acidosis. It should be used with caution in combination with diets like the ketogenic diet that may contribute to metabolic acidosis.

What Medications Are Similar?

Zonegran is one of many anticonvulsants - or anti-epilepsy drugs (AED) - used for seizure prevention in epilepsy. Other commonly prescribed AEDs include phenytoin, valproate, phenobarbital, levetiracetam, and lamotrigine.

Frequently Asked Questions

Frequently Asked Questions

  • What is Zonegran used for?

    Zonegran is used as an adjunctive (add-on) treatment with other anticonvulsants (anti-epilepsy drugs, or AEDs) for preventing partial onset seizures for adults who have epilepsy. It is also prescribed off-label for treating symptoms of Parkinson’s disease, parkinsonism, and preventing migraines.

  • How does Zonegran work?

    Zonegran stabilizes or reduces nerve activity by interacting with sodium and calcium receptors on the nerves in the brain. It is a carbonic anhydrase inhibitor and a sulfonamide.

  • What drugs should not be taken with Zonegran?

    Zonegran can cause adverse effects when it’s used with other carbonic anhydrase inhibitors or sulfonamides. Additionally, your healthcare provider may adjust your dose based on the other medicines that you take.

  • How long does it take for Zonegran to work?

    This medication should start having effects within a few hours, but you may not experience the full effects of seizure prevention until you have been regularly taking it as prescribed for several days.

  • What are the side effects of Zonegran?

    The most common side effects of Zonegran include fatigue, dizziness, impaired balance and coordination, and vomiting. Less often, it can cause serious side effects, including bleeding problems, suicidal thoughts, and organ failure.

  • How to stop taking Zonegran?

    You should not stop taking Zonegran abruptly. If you need to stop taking it, talk with your healthcare provider or pharmacist and carefully follow their instructions.

How Can I Stay Healthy While Taking Zonegran?

If you are taking Zonegran, it’s important that you take steps to get the most of its beneficial effects and to also avoid side effects. 

Considerations when taking Zonegran include: 

  • Avoid anything that can trigger a seizure like alcohol, lack of sleep, skipping meals, dehydration and flashing lights. 
  • Take Zonegran and your other medications as directed by your healthcare provider and pharmacist.
  • Be consistent with how and when you take your medication (for example, take it at the same time every day, always take it with food or always without food).
  • Tell your healthcare provider and pharmacist about any new diagnosed conditions that you may have.
  • Check with your healthcare provider and pharmacist before you start taking any new over-the-counter or prescription medications, supplements, or herbs because they can affect your tendency to have seizures. 
  • Have a care plan in place in case you have a seizure despite taking Zonegran.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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