Zonisamide
Zonegran (human) · generic zonisamide
Zonisamide is a human anti-seizure drug used in dogs, and occasionally cats, as an add-on when phenobarbital or levetiracetam alone is not enough, or as a first drug for dogs that cannot take phenobarbital. It is a generic capsule that any pharmacy can fill, and it has become much cheaper than it once was.
What it is used for
Zonisamide controls seizures by several mechanisms and lasts long enough in dogs to be given twice a day. It is used as an add-on in dogs with epilepsy not controlled by their first drug, and increasingly as a first drug because it causes less sedation than phenobarbital and needs less monitoring. Cats clear it slowly and are dosed once a day.
Sedation, wobbliness and reduced appetite are the common early effects. Rare but serious liver reactions and a kidney effect have been reported, so vets check blood work after starting. The dose is higher when it is given with phenobarbital, which speeds up its clearance.
Safety points that differ from human use
- Zonisamide is a sulfonamide; animals with a history of sulfa reactions should not receive it.
- Loss of appetite, yellow gums or vomiting after starting warrants a prompt call; the vet will check the liver.
- Never stop suddenly; the vet will taper it.
- Capsules (human)
- Compounded liquids and small capsules for cats and small dogs
- 25, 50 and 100 mg capsules
The 25 mg capsule suits small dogs and cats; larger dogs take several 100 mg capsules a day.
Why the cash price varies
Zonisamide was an expensive drug for years and some pharmacies still price it that way, but it is now a cheap generic at most; the spread between pharmacies is wide, and a large dog on several capsules a day feels it. Compounded cat doses are made to order.
How to pay less
- Ask the pharmacy whether zonisamide is on its flat-price list, and compare a second pharmacy; quotes differ a lot.
- Ask the vet for a strength that keeps the capsule count low, and for a ninety-day prescription.
- Upload the prescription to Script Unlock so licensed pharmacies can quote. You pay the pharmacy directly.
Questions for your vet
- Is this replacing or adding to my pet’s current seizure medicine?
- What blood tests are needed, and when?
- Does my pet have any history of sulfa reactions?
- What should I do if a dose is missed?
- How do we judge whether it is working?
Rules on refills, transfers and controlled substances differ by state; see pharmacy rules by state.
How Script Unlock gets you a cash price for your pet’s zonisamide prescription
Prices on this site come from pharmacies responding to a real prescription. We do not publish estimated, average or "typical" prices, because none of those would be your price.
- 1You upload your prescription
A photo of your your pet’s zonisamide prescription prescription is enough. Nothing is sold on the site; you are asking pharmacies to quote.
- 2Licensed pharmacies respond
Pharmacies that Script Unlock has verified see the request and each can reply with its own cash price for your exact drug, strength and quantity.
- 3You choose and pay the pharmacy
You compare the responses, pick a pharmacy, and pay that pharmacy directly when you collect. Script Unlock never takes a patient payment and never sets the price.
Related pet medications
Sources
- Merck Veterinary Manual
- FDA Orange Book (approved generics and therapeutic equivalence)
- MedlinePlus drug information (National Library of Medicine)
- ASPCA Animal Poison Control
Written by the Script Unlock editorial team from the sources above. Not yet reviewed by a veterinarian or veterinary pharmacist. Last checked 2026-10-03. Nothing here replaces your vet\u2019s directions; doses for animals are set by weight and species.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.