Zonisamide: uses, dosing, side effects & brands
Zonisamide is an anti-epileptic agent sold in the U.S. under 2 brand and generic names, for partial epilepsies. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Anti-Epileptic Agent
- Treats (across its forms)
- Partial Epilepsies
- Available as
- Suspension · Capsule
- Sold as
- 2 products — Zonisade and Zonegran
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $3 for a 30-count supply — not your price
How Zonisade is dosed
From the FDA label for Zonisade (application NDA214273). Other zonisamide products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
The recommended initial dosage of ZONISADE is 100 mg daily. The dosage may be increased by 100 mg daily every two weeks, based on clinical response and tolerability, to 400 mg daily. Patients who are tolerating ZONISADE at 400 mg daily and require further reduction of seizures may be increased up to a maximum dosage of 600 mg daily ( 2.2 ). • ZONISADE is given orally and can be taken with or without food ( 2.2 ). 2.1 Recommended Assessments for Safety To assess for metabolic acidosis, obtain baseline serum bicarbonate prior to initiating ZONISADE, and obtain periodic serum bicarbonate during treatment [see Warnings and Precautions ( 5.8 )]. 2.2 Recommended Dosage Administer ZONISADE once or twice daily with or without food. The recommended initial dosage of ZONISADE is 100 mg daily. The dosage may be increased by 100 mg daily every two weeks, based on clinical response and tolerability, to 400 mg daily. Patients who are tolerating ZONISADE at 400 mg daily and require further reduction of seizures may be increased up to a maximum dosage of 600 mg daily. However, evidence from controlled trials shows no suggestion of increasing response above 400 mg/day [see Clinical Studies ( 14 )] . 2.3 Important Administration Information Shake well before every administration. To administer ZONISADE directly into the mouth, it is important that ZONISADE be measured with an accurate measuring…
Everything below is the FDA label for Zonisade (suspension). Zonisamide is also sold as capsule, and those are different medicines to take — follow the label for the one you were prescribed.
Zonisade side effects
The following clinically signification adverse reactions are described elsewhere in the labeling: • Potentially Fatal Reactions to Sulfonamides [see Warnings and Precautions ( 5.1 )] • Serious Skin Reactions [see Warnings and Precautions ( 5.2 )] • Serious Hematologic Events [see Warnings and Precautions ( 5.3 )] • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multi-Organ Hypersensitivity [see Warnings and Precautions ( 5.4 )] • Oligohidrosis and Hyperthermia in Pediatric Patients [see Warnings and Precautions ( 5.5 )] • Acute Myopia and Secondary Angle Closure Glaucoma [see Warnings and Precautions ( 5.6 )] • Suicidal Behavior and Ideation [see Warnings and Precautions ( 5.7 )] • Metabolic Acidosis [see Warnings and Precautions ( 5.8 )] • Seizures on Withdrawal of Antiepileptic Drugs [see Warnings and Precautions ( 5.9 )] • Teratogenicity [see Warnings and Precautions ( 5.10 )] • Cognitive/Neuropsychiatric Adverse Reactions [see Warnings and Precautions ( 5.11 )] • Hyperammonemia and Encephalopathy [see Warnings and Precautions ( 5.12 )] • Kidney Stones [see Warnings and Precautions ( 5.13 )] • Effect on Renal Function [see Warnings and Precautions ( 5.14 )] • Status Epilepticus [see Warnings and Precautions ( 5.15 )] The most common adverse reactions with ZONISADE (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in…
Who shouldn’t take Zonisade
ZONISADE is contraindicated in patients who have demonstrated hypersensitivity to sulfonamides or zonisamide. ZONISADE is contraindicated in patients who have demonstrated hypersensitivity to sulfonamides or zonisamide ( 4 ).
Zonisade drug interactions
ZONISADE should be used with caution if used in combination with alcohol or other CNS depressants ( 7.1 ). • Concomitant use of ZONISADE with any other carbonic anhydrase inhibitor may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation ( 7.2 ). 7.1 CNS Depressants Concomitant use of ZONISADE with other CNS depressants, including alcohol, may increase the risk of CNS depression, as well as other cognitive and/or neuropsychiatric adverse events [see Warnings and Precautions ( 5.11 )] . 7.2 Other Carbonic Anhydrase Inhibitors Concomitant use of ZONISADE, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor, may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation [see Warnings and Precautions ( 5.8 , 5.15 )] . Therefore, if ZONISADE is given concomitantly with another carbonic anhydrase inhibitor, monitor the patient for the appearance or worsening of metabolic acidosis [see Clinical Pharmacology ( 12.1 , 12.3 )] . 7.3 CYP3A4 Inducers If co-administration with a potent CYP3A4 inducer is necessary, the patient should be closely monitored and the dose of ZONISAMIDE and other drugs that CYP3A4 substrates may need to be adjusted [see Clinical Pharmacology ( 12.3 )] .
Every zonisamide product we track (2)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 70/100 | Prescription | Suspension | Generic | $3 | View → | |
| 2 | Not yet rated | Prescription | Capsule | Generic | $3 | View → |
What zonisamide pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| 258;258 | 25 mg | white, white | capsule | — |
| 259;259 | 50 mg | white, gray | capsule | — |
| 260;260 | 100 mg | white, orange | capsule | — |
| G24;25 | 25 mg | blue, white | capsule | — |
| ZNS;100 | 100 mg | pink, white | capsule | — |
| G24;25 | 25 mg | blue, white | capsule | — |
| G24;50 | 50 mg | yellow, white | capsule | — |
| G24;100 | 100 mg | green, white | capsule | — |
| ZNS;25 | 25 mg | white | capsule | — |
| ZNS;50 | 50 mg | white | capsule | — |
| ZNS;100 | 100 mg | pink, white | capsule | — |
Can you crush or split zonisamide?
At least one zonisamideproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.
What each zonisamide label says about crushing, splitting and chewingHow long zonisamide keeps
The date on a sealed pack is not the only one: some zonisamide labels start a second clock once the product is opened or mixed, as short as 30 days.
Does zonisamide expire? The in-use limits and storage rules from its labelsZonisamide and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for zonisamide: levels in milk, effects in breastfed infants, and the drugs it would consider insteadLimited information indicates that maternal doses of zonisamide up to 400 mg daily produce high levels in milk and infant serum. Infant serum levels in neonates decrease to below the therapeutic range after 3 days and continue to decrease during the first month of life while continuing nursing. Although no adverse reactions have been reported in breastfed infants, the number of infants reported have been small. Alternative drugs are preferred, but if it must be given, monitor the infant for drowsiness, adequate weight gain, and developmental milestones, especially in younger or exclusively breastfed infants and when using combinations of anticonvulsant drugs. Some clinicians recommend that mothers taking zonisamide only partially breastfeed in order to reduce the exposure of the infant to the drug and to consider monitoring infants’ serum zonisamide concentrations.
National Institute of Child Health and Human Development, record revised August 15, 2025. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about zonisamide
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 10,712 reports naming zonisamide, and the FDA flagged 77% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- seizure1,177 reports
- fatigue498 reports
- somnolence471 reports
- dizziness411 reports
- nausea390 reports
- fall365 reports
- headache365 reports
- convulsion324 reports
Read these as a signal, not a rate. A report does not mean zonisamide caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 26, 2026.
Related calculators
Frequently asked questions
What is Zonisade?
Zonisade (Zonisamide) is an anti-epileptic agent used to treat Partial Epilepsies.
What kind of drug is zonisamide?
The FDA classifies zonisamide as an anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take zonisamide with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run zonisamide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is zonisamide sold under?
We track 2 zonisamide-containing products in the U.S.: Zonisade and Zonegran. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does zonisamide come in?
Across the brands we track, zonisamide is currently marketed as suspension and capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic zonisamide?
We do not currently list a generic-labelled zonisamide product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Zonisamide: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/zonisamide
- MLA
- “Zonisamide: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/zonisamide.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for zonisamide on DailyMed (NIH) ↗.