What is zonisamide?

Zonisamide is used together with other medicines to treat partial seizures in adults and teenagers at least 16 years old.

Zonisamide may also be used for purposes not listed in this medication guide.

Important Information

Taking zonisamide can cause permanent vision loss. Tell your doctor right away if you have any eye pain or redness or any changes in your vision.

Some people have thoughts about suicide while taking zonisamide. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Before taking this medicine

You should not use zonisamide if you are allergic to it.

You may not be able to take zonisamide if you have ever had a severe allergic to a sulfa drug.

Tell your doctor if you have ever had:

• liver disease;
• kidney disease;
• high levels of ammonia;
• stomach flu or illness causing diarrhea;
• a growth disorder;
• a bone disorder that causes soft or weak bones or low bone mineral density;
• depression, or suicidal thoughts or actions;
• if you have ever had metabolic acidosis (too much acid in your blood); or
• if you have been on a ketogenic diet (high-fat, high-protein, low-carb).

Some people have thoughts about suicide while taking zonisamide. Your doctor will need to check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Zonisamide may harm an unborn baby. Use effective birth control to prevent pregnancy, and tell your doctor if you become pregnant.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of zonisamide on the baby.

You should not breastfeed while using zonisamide.

Zonisamide is not approved for use by anyone younger than 16 years old.

How should I take zonisamide?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Zonisamide can be taken with or without food.

Swallow the capsule whole and do not crush, chew, break, or open it.

While using zonisamide, you may need frequent blood tests.

Do not stop using zonisamide suddenly, even if you feel fine. Stopping suddenly may cause increased seizures. Follow your doctor’s instructions about tapering your dose.

Do not share zonisamide with another person, even if they have the same symptoms you have.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention

Overdose symptoms may include slow heart rate, feeling light-headed, fainting, and slow or shallow breathing.

What should I avoid while taking zonisamide?

Avoid driving or hazardous activity until you know how zonisamide will affect you. Your reactions could be impaired.

Drinking alcohol with this medicine can cause side effects.

Zonisamide side effects

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 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:

• eye pain or redness or any changes in your vision;
• decreased sweating, feeling very hot;
• signs of metabolic acidosis–confusion, vomiting, lack of energy, 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.

Zonisamide dosing information

Usual Adult Dose for Seizures:

16 years of age and older:
-Initial dose: 100 mg orally once a day
-Titration: After 2 weeks at 100 mg/day, the dose may be increased to 200 mg/day as either a single or divided dose (100 mg orally 2 times a day) for at least 2 weeks; it can then be increased to 300 mg/day, then 400 mg/day either as a single daily dose or divided into 2 daily doses, with the dose stable for at least 2 weeks to achieve steady state at each level
-Maintenance dose: 400 mg/day
-Maximum dose: 600 mg/day

Comments:
-This drug may be taken with or without food.
-Capsules should be swallowed whole.
-Because of the long half-life of this drug, up to 2 weeks may be required to achieve steady state levels upon reaching a stable dose or following dosage adjustment.
-The prescriber may wish to prolong the duration of treatment at the lower doses in order to fully assess the effects of this drug at steady state (noting that many of the side effects are more frequent at doses of 300 mg per day and above). Although there is some evidence of greater response at doses above 100 to 200 mg/day, the increase appears small and formal dose response studies have not been conducted.

Use: As adjunctive therapy in the treatment of partial seizures

Usual Pediatric Dose for Seizures:

Less than 16 years of age: Not recommended
16 years of age and older: See adult dosing

What other drugs will affect zonisamide?

Taking zonisamide with other drugs that make you sleepy can worsen this effect. Ask your doctor before taking zonisamide with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety or depression.

Other drugs may interact with zonisamide, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.