Is zonisamide (Zonegran) a controlled substance?

No, zonisamide (Zonegran) isn't a [controlled substance](https://www.goodrx.com/drugs/medication-basics/what-are-controlled-substances). It isn't known to have a risk of addiction or dependence.

Does zonisamide (Zonegran) make you sleepy?

Yes. Zonisamide (Zonegran) can make you sleepy, especially at higher doses. Don't drive or do anything that requires you to be alert until you know how this medication affects you. It's a good idea to avoid alcohol and [medications that make you sleepy](https://www.goodrx.com/drugs/side-effects/prescription-make-you-tired), like opioids and some anxiety medications, while taking zonisamide (Zonegran). This is because it can make sleepiness more likely or be more severe. Talk to your prescriber if you feel too sleepy after taking zonisamide (Zonegran).

Can you drink alcohol with zonisamide (Zonegran)?

It's not recommended to drink alcohol while you're taking zonisamide (Zonegran). Alcohol can worsen side effects like drowsiness and dizziness. Drinking too much alcohol can also [raise your risk of having a seizure](https://www.goodrx.com/conditions/seizure/drugs-that-lower-seizure-threshold). Talk to your prescriber about how much you usually drink. They can talk to you about how to take this medication safely.

Can you take zonisamide (Zonegran) while pregnant?

If you're pregnant or planning to be, talk to your prescriber. They can explain the risks and benefits of taking zonisamide (Zonegran) during pregnancy. It's not clear if this medication can harm an unborn baby. It's still important to [keep seizures under control](https://pmc.ncbi.nlm.nih.gov/articles/PMC4784252/) while pregnant to avoid problems. If you take zonisamide (Zonegran) while pregnant, your prescriber might recommend you to join the [North American Antiepileptic Drug Pregnancy Registry](https://www.aedpregnancyregistry.org/). This program helps researchers learn more about how seizure medications affect pregnancy. Your prescriber can help you choose the safest option for you and your baby.

zonisamide

Generic Zonegran

Used for Epilepsy

Zonisamide (Zonegran) is an antiepileptic. It helps control partial-onset seizures in people 16 years and older with epilepsy. It's usually taken along with other seizure medications. Zonisamide comes as a capsule in both generic forms and the brand name Zonegran. It also comes as a liquid called Zonisade, which is brand name only. You take it by mouth once or twice a day. Common side effects are drowsiness, dizziness, and headache. Some medications can interact with zonisamide (Zonegran) and make side effects worse or raise the risk of seizures.

Reviewed by:

Kristianne Hannemann, PharmD

Cydnee Ng, PharmD

Last reviewed on February 3, 2026

What is Zonisamide (Zonegran)?

What is Zonisamide (Zonegran) used for?

Partial-onset seizures in people ages 16 years and older

How Zonisamide (Zonegran) works

Zonisamide (Zonegran) is a type of antiepileptic, or an anti-seizure medication. It's not exactly clear how the medication works to treat seizures. But it's thought to block nerve signaling in the brain. This might help calm your brain activity to control seizures.

When does Zonisamide (Zonegran) start working?Time passed since treatment started:

HOURS

DAYS

WEEKS

Full effect

MONTHS

Drug facts

Common Brands	Zonegran, Zonisade
Drug Class	Antiepileptic
Controlled Substance Classification	Not a controlled medication
Generic Status	Lower-cost generic available
Availability	Prescription only

Common Brands

Zonegran, Zonisade

Drug Class

Antiepileptic

Controlled Substance Classification

Not a controlled medication

Generic Status

Lower-cost generic available

Availability

Prescription only

Side effects of Zonisamide (Zonegran)

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

Sleepiness (17%)
Dizziness (13%)
Low appetite (13%)
Headache (10%)
Nausea (9%)
Agitation or irritability (9%)
Fatigue (8%)
Tiredness (7%)
Stomach pain (6%)
Confusion (6%)
Depression (6%)
Trouble sleeping (6%)
Problems with concentration or memory (6%)
Clumsy movement (6%)
Double vision (seeing double; 6%)

Less Common Side Effects

Diarrhea
Indigestion
Constipation
Kidney stones
Dry mouth
Speech problems
Tingling in your arms, hands, or feet
Weight loss
Slow thinking
Anxiety or nervousness
Rash
Changes in taste
Flu-like symptoms

Zonisamide (Zonegran) serious side effects

Contact your healthcare provider immediately if you experience any of the following.

Serious allergic reaction: swelling of the face and neck area, trouble breathing, widespread skin redness or rash, fever
Serious skin reaction: blisters, skin peeling, fever, flu-like symptoms
Suicidal thoughts or behavior
Unusual changes in mood, thoughts, or behavior
Heat stroke: sweating less than usual; fever; hot, dry, red skin; confusion
Eye problems: sudden blurry vision, trouble seeing far away, sudden eye pain or eye redness
Kidney problems: sudden back pain, stomach pain, blood in the urine
High acid levels: fast breathing, fast heartbeat, tiredness, confusion, loss of appetite, nausea, weakness

Source: DailyMed

The following Zonisamide (Zonegran) side effects have also been reported

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

Discouragement

double vision

feeling sad or empty

irritability

lack of appetite

loss of interest or pleasure

mood or mental changes

shakiness or unsteady walking

tiredness

trouble with concentrating

trouble with sleeping

Less common

Agitation

bruising

delusions

hallucinations

large, flat blue or purplish patches on the skin

rash

Incidence not known

Blurred vision

change in near or distance vision

difficulty in focusing eyes

eye pain

increase in frequency of seizures

swelling of the face

yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Abdominal or stomach pain

anxiety

diarrhea

difficulty with memory

dizziness

double vision

headache

loss of appetite

nausea

restlessness

sleepiness

unusual drowsiness

unusual tiredness or weakness

Less common

Aching muscles or joints

acid or sour stomach

bad, unusual, or unpleasant taste in the mouth

belching

change in taste

chills

constipation

difficulty with speaking

difficulty with thinking

dry mouth

fever

general ill feeling

headache

heartburn

indigestion

mental slowness

nervousness

runny or stuffy nose

sneezing

tingling, burning, or prickly feelings on the skin

uncontrolled, back and forth, or rolling eye movements

weight loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

See more Zonisamide (Zonegran) side effects

Get your GoodRx coupon

Avg retail price

$9.000

GoodRx discount

$9.00

See prices

Pros and cons of Zonisamide (Zonegran)

Pros

Can be a good add-on option when other medications aren't working well enough to help control seizures
Can take with or without food
Also comes as a liquid suspension for people who have problems swallowing pills

Cons

Not approved for children younger than 16
Can take several weeks to get the full benefits of the medication
Not safe to take if you have a sulfa allergy

Pharmacist tips for Zonisamide (Zonegran)

Take zonisamide (Zonegran) as prescribed. Your prescriber will tell you whether to take it once or twice a day. You can take the medication with or without food.
Swallow the zonisamide (Zonegran) capsule whole. Don't crush or open it because it can affect how the medication works. If you have trouble swallowing it whole, talk to your prescriber about your options.
Zonisamide (Zonegran) can make you dizzy or sleepy. It can also make it hard to focus, think clearly, or react quickly. Don't drive or do anything that needs your full attention until you know how this medication affects you. If these side effects make it too hard to go about your day, talk to your prescriber.
It's best to avoid alcohol while taking zonisamide (Zonegran). Alcohol can make side effects like tiredness, dizziness, and problems focusing worse. This can be risky, like if you need to drive. Drinking a lot of alcohol can also make seizures more likely. Talk to your prescriber about your drinking habits and how to take this medication safely.
Tell your prescriber and pharmacist about all the medications you take or plan to take. This is very important if you take other medications that make you tired, like anxiety medications or muscle relaxers. Taking these with zonisamide (Zonegran) can raise the risk of side effects like sleepiness, dizziness, and trouble staying alert. Your care team can check for drug interactions and make changes to your treatment if needed to keep you safe.
Zonisamide (Zonegran) can sometimes cause kidney stones. Be sure to drink plenty of fluids to help lower your risk. If you have a kidney stone, it usually passes on its own might need treatment at times. Tell your care team if you feel pain in your mid-to-lower back, side, lower stomach, or groin. Also pay attention if you also feel restless or have dark, cloudy, or bloody urine. These can be signs of kidney stones.
Don't stop taking zonisamide (Zonegran) without talking to your prescriber first. Stopping it suddenly can cause seizures to come back and sometimes be worse. Your prescriber will help lower your dose slowly over time so you can stop safely.

For the zonisamide liquid suspension (Zonisade brand name):

Store the liquid bottle at room temperature (up to 77ºF). The medication is good for 30 days after opening the bottle. After this time, throw it away, even if there's some medication left in the bottle.
Shake the bottle well before using. This helps mix the medication so you get the right amount when you measure it out.
Use an oral dosing syringe or medication cup to measure your dose in milliliters (mL). You shouldn't use kitchen spoons because they might not be accurate, even if you're using a teaspoon or tablespoon. Talk to your pharmacist or prescriber if you don't have a proper dosing device.

Common questions about Zonisamide

No, Zonisamide isn't a controlled substance. It isn't known to have a risk of addiction or dependence.

Yes. Zonisamide can make you sleepy, especially at higher doses. Don't drive or do anything that requires you to be alert until you know how this medication affects you. It's a good idea to avoid alcohol and medications that make you sleepy, like opioids and some anxiety medications, while taking Zonisamide. This is because it can make sleepiness more likely or be more severe. Talk to your prescriber if you feel too sleepy after taking Zonisamide.

No, you shouldn't open the Zonisamide capsules. Be sure to swallow them whole with water. Tell your prescriber if you have trouble swallowing the capsules. They might be able to switch you to the liquid version instead. Or, they can see if there's a different seizure medication that might be easier for you to take.

In studies, few people said they lost weight while taking Zonisamide. This happened in about 3% of people taking the medication, so it doesn't seem common. Note that around 13% said they had less of an appetite. If you don't feel hungry, you might eat less, which might affect your nutrition and weight over time. If you notice unusual weight loss while taking Zonisamide, tell your prescriber or primary care provider. They can help you manage your weight.

It takes about 10 to 14 days for Zonisamide to fully leave your system. This is based on the medication's half-life. But the exact amount of time it takes to leave your body can depend on some other things. This can include your other health conditions and what other medications you take. Be sure to keep taking Zonisamide every day. This helps the medication levels stay high enough in the body to help you. Talk to your prescriber if you have questions about how long Zonisamide stays in your system.

It's not recommended to drink alcohol while you're taking Zonisamide. Alcohol can worsen side effects like drowsiness and dizziness. Drinking too much alcohol can also raise your risk of having a seizure. Talk to your prescriber about how much you usually drink. They can talk to you about how to take this medication safely.

Don't stop taking Zonisamide all at once unless you're having an allergic reaction to it. Stopping suddenly can cause seizures to come back, last longer, or happen more often. This can be dangerous. If you want to stop this medication for some other reason, talk to your prescriber first. If stopping is the right choice, your prescriber will help lower your dose slowly until you can stop safely.

If you're pregnant or planning to be, talk to your prescriber. They can explain the risks and benefits of taking Zonisamide during pregnancy. It's not clear if this medication can harm an unborn baby. It's still important to keep seizures under control while pregnant to avoid problems. If you take Zonisamide while pregnant, your prescriber might recommend you to join the North American Antiepileptic Drug Pregnancy Registry. This program helps researchers learn more about how seizure medications affect pregnancy. Your prescriber can help you choose the safest option for you and your baby.

Risks and warnings for Zonisamide (Zonegran)

Zonisamide (Zonegran) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

Potentially serious allergic reaction to sulfa medications

Risk factors: Allergy to sulfonamides

Zonisamide (Zonegran) is a sulfonamide, or a sulfa medication. Don’t take this medication if you're allergic to other sulfa drugs. Some examples include Bactrim (sulfamethoxazole / trimethoprim) and sulfasalazine (Azulfidine). If you have a sulfa allergy, you might have a severe allergic reaction to zonisamide (Zonegran).

Get medical help right away or go the emergency room if you have a skin rash, blisters, or peeling skin while taking zonisamide (Zonegran). Also get help right away if you have swelling of the face or throat or trouble breathing. These can be signs of a very serious allergic reaction.

Serious skin reactions

Although rare, some people have had life-threatening skin reactions while taking zonisamide (Zonegran). In most cases, people start out with flu-like symptoms, such as fever, cough, sore throat, and fatigue. Then, a painful rash or blisters on the body can appear. If you notice any rash while taking this medication, tell your care team right away.

DRESS syndrome (a serious allergic reaction)

It's rare, but some people taking zonisamide (Zonegran) have had a drug reaction with eosinophilia and systemic symptoms (DRESS syndrome). This reaction can be life-threatening and can damage organs like the heart, kidneys, and liver.

Early signs can include a widespread rash or red skin, fever, swelling of the face, or yellow skin or eyes. Get medical help right away if you notice any of these symptoms while taking zonisamide (Zonegran).

Less sweating and risk of heat stroke

Risk factors: Under age 18 | Spending a lot of time in hot weather or hot environments | Taking other medications that make you more likely to overheat

Zonisamide (Zonegran) can make you sweat less. This can make it harder for you to control your body temperature. It can put you at higher risk of heat stroke, which can be life-threatening if not treated.

The risk of this side effect is higher in younger people who take zonisamide (Zonegran). The risk is also higher if you take other medications that might cause less sweating, such as anticholinergics.

To prevent overheating, drink plenty of liquids each day. Also stay in the shade and avoid being in the sun too long if the weather is hot.

Serious eye problems

Some people taking zonisamide (Zonegran) have had eye problems. They can include sudden blurry vision, trouble seeing far away, and higher pressure in the eye. A sudden rise in eye pressure can also cause eye pain and eye redness. If not treated, this can lead to permanent vision loss.

Eye problems can appear within 1 month of starting zonisamide (Zonegran). Tell your prescriber or eye specialist if you notice any sudden vision changes or eye pain while taking this medication.

Suicidal thoughts or behavior

Antiepileptics like zonisamide (Zonegran) can raise the risk of suicidal thoughts or behavior. The risk can be higher starting as early as 1 week of taking this medication.

Be sure you and your loved ones watch for depressed mood or any unusual changes in mood or behavior. If this happens, let your care team know. Call 911 right away if you have thoughts of hurting yourself. You can also contact the National Suicide Prevention Lifeline by calling or texting 988.

Changes in mood or thinking, or problems with cognitive skills

Zonisamide (Zonegran) can make it harder to concentrate. It can also cause problems with speech, language, or coordination. These issues have happened after 6 to 10 weeks of treatment at doses greater than 300 mg per day. Sometimes, people have also had mood changes, like new or worsening depression. Tell your care team if you or someone close to you notices unusual behavior, thoughts, or mood while you're taking zonisamide (Zonegran).

Effect on kidney function

Risk factors: History of kidney problems

Zonisamide (Zonegran) can affect how well your kidneys work. This has happened within the first 4 weeks of treatment. It might also last over time.

Your prescriber might order blood tests during treatment to check your kidneys. Also tell your care team if you notice changes in how often you urinate, swelling in your feet or ankles, tiredness, or muscle cramps. This could be signs of kidney problems. If there are signs of problems, your prescriber might consider stopping zonisamide (Zonegran).

Too much acid in the blood

Risk factors: Diarrhea | Kidney problems | Severe lung problems | Ketogenic diet | Taking other medications that raise the acid levels in your blood (e.g., acetazolamide)

In rare cases, zonisamide (Zonegran) can cause too much acid to build up in the blood. This is called metabolic acidosis. If not treated, it can cause kidney stones or weak bones. It can also raise the risk of having high ammonia levels in the blood, which can be serious.

Your prescriber might ask for regular blood tests while you're taking zonisamide (Zonegran). This helps check your risk of acid levels. Call your care team if you have fast, deep breathing or feel very tired or confused. These can be early signs of high acid levels.

If metabolic acidosis happens, your prescriber might lower your dose or stop zonisamide (Zonegran). If you keep taking zonisamide (Zonegran), your prescriber might also give you other medications to treat the acid problem.

High ammonia levels

Risk factors: Metabolic acidosis from zonisamide (Zonegran) | Genetic conditions that cause high ammonia levels | Taking other medications that raise ammonia levels, like valproic acid or topiramate (Topamax)

Zonisamide (Zonegran) has a risk of causing metabolic acidosis, or high acid levels. This in turn can raise your risk of high ammonia levels in the blood. It can affect the brain and cause tiredness, trouble thinking, or vomiting. If these symptoms happen, let your care team know right away. They'll check your ammonia levels with blood tests. If they're too high, your prescriber can lower your dose or stop the medication.

Withdrawal seizures after stopping zonisamide (Zonegran) suddenly

Don't suddenly stop taking zonisamide (Zonegran) without talking to your prescriber first. Stopping the medication too fast can cause your seizures to come back or become worse. These withdrawal seizures can sometimes be very dangerous.

If you need to stop taking zonisamide (Zonegran), your prescriber will work with you to do this safely. They'll lower your dose slowly over time to help prevent withdrawal seizures from happening.

Harm to an unborn baby

Based on animal studies, zonisamide (Zonegran) can harm an unborn baby if taken during pregnancy. If you can become pregnant, use birth control while taking this medication and for 1 month after your last dose. This helps prevent pregnancy and risks to an unborn baby.

Tell your prescriber right away if you become pregnant while taking zonisamide (Zonegran). It should only be used during pregnancy if the benefits are greater than the risks. Your prescriber can help you decide what the safest option is for you.

Zonisamide (Zonegran) dosage

The average cost for 120 capsules of 100mg of Zonisamide (Zonegran) is $24.29 with a free GoodRx coupon. This is 82.13% off the average retail price of $135.96.

Capsule

Dosage	Quantity	Price as low as	Price per unit
100mg	120 capsules	$24.29	$0.20
25mg	60 capsules	$11.95	$0.20
50mg	60 capsules	$9.00	$0.15

See more Zonisamide (Zonegran) dosage

Interactions between Zonisamide (Zonegran) and other drugs

Zonisamide (Zonegran) may interact with certain medications or supplements. Always let your doctor and pharmacist know about any other medications or supplements (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. The list below does not include all possible drug interactions with Zonisamide (Zonegran). Please note that only the generic name of each medication is listed below.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Methenamine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Aminolevulinic Acid
Ginkgo

See more Zonisamide (Zonegran) interactions

How much does Zonisamide (Zonegran) cost?

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Zonegran (brand)

GoodRx lowest price

$9.00

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$9.00

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Zonisamide (Zonegran) contraindications

Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Zonisamide (Zonegran) will not be safe for you to take.