Zonegran (zonisamide) is an antiseizure drug that is chemically classified as a sulfonamide and that is unrelated to other antiseizure agents, such as Dilantin (phenytoin).

The physical side effects of zonisamide are any form of skin rash; hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Other possible side effects include mood or behavior changes, anxiety, panic attacks, trouble sleeping, or feeling impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or having thoughts about suicide or hurting yourself.

This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely.

Zonisamide was discovered in 1972 and marketed in the United States starting in 2000 as Zonegran.

This description is adapted from information sources found online, and is in no way meant to replace or substitute for professional medical advice. If you are in pain, or considering taking this or any other medicine, contact your medical professional for assistance rather than using the internet as your sole source of information.

My Personal Experience

After more than twenty years on Dilantin, it was determined that I should be switched over to another medication, and Zonegran was chosen as the winner. During approximately a two-week period, I was gradually weaned off of Dilantin and built up my Zonegran dosage.

During that time, it was a little rough – I’m sure partially because of my own nervousness and partially because I had a bit of an extra dose inside me. Once the Dilantin cleared my system and I had built up to the new 600mg dose of Zonegran, however, things have gone swimmingly.

My own understanding is that the medicine has a longer life in the bloodstream than Dilantin, so that rather than peaks and valleys after taking it, it provides a more even level over time – and that is probably a good thing (and hopefully I understand correctly). All in all I feel like I am more alert and that I am in better health than I was, plus there are fewer drug interactions and downsides than there were with Dilantin.

15 Replies to “Zonegran”

  1. Hi Jennifer –

    I’m afraid that I don’t have mood swings, and I’m also not a doctor, so I can’t say. I’ve been taking Zonegran for a while now (about 2.5 years), and I feel much better than when I was on Dilantin), but that doesn’t mean that it won’t affect you differently.

  2. I am new to using Zonegran. I am on my “3rd” pill. Is it normal to have total mood swings? I feel like I am happy one second, and then the next i feel mad. Also I have noticed My memory has gone capoo! I know what I want to say, but I cant remember it,or I just cant say it. Is this going to go away? Is this just happening because I’m going threw the stages of increasing my doses of medication? Please help.


  3. Hi Terri –

    That is bad news. I do hope that things get better for you somehow, and I also hope that this is an oddity. Definitely one of the things that I was worried about in switching medicine was that Dilantin was at least a known commodity. The lesser of two evils, perhaps.

    In any case, thanks for the information, and good luck – please let us know how it goes for you!

  4. Hi Trish – Sorry for the delay, I’ve had a bit of difficulty getting things up and running after some login issues!

    Yes, things are going well (no seizures, at any rate), and the headaches are seeming to be kept to a minimum as well. I do have them from time to time, bu at this point, it seems to be more related to allergies than anything else – so I’m fairly sure that the Zonegran was a good move.

  5. Thanks for the response. I’m glad to hear you have had no more seizures, and hopefully the headaches will one day subside. Would it be possible to make phone contact with you? I’m wanting to ask you a few more questions about Zonegran. I’ve been driving my girlfriend crazy with fears (both real and imagined), of side effects from this drug. I had a bad experience on Lamictal. Anyway, if you don’t mind sharing your number you can email me at


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