Banzel (rufinamide) is a prescription drug used to treat seizures linked to Lennox-Gastaut syndrome. Banzel can cause side effects that range from mild to serious. Examples include sleepiness, headache, and dizziness.

Specifically, Banzel is used in adults and children ages 1 year and older to treat seizures associated with Lennox-Gastaut Syndrome (LGS). Banzel is used only along with other seizure medications.

The active ingredient in Banzel is rufinamide. The drug comes as oral tablets and oral suspension (a type of liquid mixture). The active ingredient, rufinamide, is also available as a generic medication.

Keep reading to learn about common, mild, and serious side effects that Banzel can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during their Banzel treatment. Examples of the drug’s commonly reported side effects include:

  • dizziness
  • fatigue (low energy)
  • headache
  • vomiting
  • sleepiness

The following sections include more side effects of Banzel. Each person’s experience with side effects may differ.

Keeping track of side effects

During your Banzel treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Sharing notes with your doctor will help them learn more about how Banzel affects you. They can then use this information to adjust your treatment plan if needed.

Mild side effects have been reported with Banzel. These include:

  • dizziness
  • double vision
  • fatigue (low energy)
  • headache
  • nausea and vomiting
  • sleepiness
  • upper belly pain

In most cases, these side effects should be temporary. And some may be managed easily. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop Banzel treatment unless your doctor recommends it.

Banzel may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

Serious side effects have been reported with Banzel. These include:

If you develop serious side effects while taking Banzel, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911. Or call your local emergency number.

You can learn more about these side effects in the “Side effects explained” section:

  • low white blood cell count (leukopenia)
  • brain and nerve effects
  • suicidal thoughts and behaviors

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Banzel, visit MedWatch.

Allergic reaction

For some people, Banzel can cause an allergic reaction. But it’s not clear whether this side effect occurred in the drug’s studies.

In general, symptoms of allergic reaction can be mild or serious.

Banzel can cause a rare, serious allergic reaction known as DRESS. This type of drug reaction stimulates the actions of your immune system. And it causes eosinophils (a type of white blood cell) to attack parts of your body, including:

  • skin
  • liver
  • kidneys
  • lungs

Symptoms you may see with DRESS include:

  • fever
  • sore throat
  • swollen face and swollen lymph nodes
  • shortness of breath
  • skin that has the appearance of a sunburn (rash may or may not occur)
  • tender abdomen
  • body aches
  • dark urine
  • skin itching and hives
  • jaundice (skin and whites of the eyes turn yellow)

If you develop any of these symptoms, seek emergency medical treatment. Call 911 or your local emergency number. DRESS is considered a medical emergency but can be successfully treated if caught early.

What might help

You might have mild symptoms of an allergic reaction, such as a mild rash. Even so, it’s essential to call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue Banzel treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911. Or call your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

Your doctor can confirm whether you’ve had a serious allergic reaction to Banzel. If so, they may have you switch to a different treatment.

Get answers to some frequently asked questions about Banzel’s side effects.

How do the side effects of Onfi (clobazam) compare to those of Banzel?

Onfi (clobazam) and Banzel (rufinamide) both treat seizures but have some different side effects. Both drugs can cause:

  • sleepiness
  • brain and nerve effects
  • fatigue (low energy)
  • mood changes

Studies show that Onfi has a risk of respiratory depression, dependence, misuse, and life threatening withdrawal. These are not known side effects of Banzel. (Dependence is when your body needs the drug to function as usual. Misuse is taking a drug in a way other than how a doctor prescribes it. Withdrawal is when you stop taking a drug your body is used to and experience uncomfortable side effects.)

If you have questions about choosing treatment with Onfi or Banzel, check with your doctor or pharmacist.

Can Banzel cause weight gain or loss?

Weight changes were not reported in studies of adults taking Banzel. But weight loss occurred in children ages 1 to younger than 4 years. The side effect in these children may be related to decreased appetite.

If you’re concerned about weight changes during Banzel treatment, check with your doctor or pharmacist.

Learn more about some of the side effects Banzel may cause.

Low white blood cell count (leukopenia)

Low white blood cell count (leukopenia) was a common side effect reported in studies of Banzel. Low white blood cells may cause symptoms such as:

  • long-lasting infection
  • body aches
  • rash
  • headache
  • fever or chills
  • fatigue (low energy)

Factors that can increase the risk of low white blood cells when taking this drug include:

  • bone marrow or immune system problems
  • taking other medications, such as chemotherapy, that can cause low white blood cells
  • a viral infection, such as HIV, COVID-19, or hepatitis
  • inadequate nutrition

What might help

If you’re at risk of developing low white blood cells during Banzel treatment, try these recommendations:

  • Eat a balanced diet.
  • Keep your vaccinations up to date, such as COVID-19 and flu vaccines.
  • Wash your hands frequently with soap and water or hand sanitizer.

Also, talk with your doctor or pharmacist. They may recommend taking specific vitamins or adjusting your dose of Banzel. Some people have chronically low white blood cell counts with Banzel. Their doctor may switch them to a different antiseizure medication.

Brain and nerve effects

Brain and nerve effects were a common side effect reported in studies of Banzel. Brain and nerve effects are related to Banzel’s mechanism of action (how the drug works in the body). This action slows electrical activity in the brain and may cause symptoms such as:

  • excessive sleepiness or fatigue (low energy)
  • unsteady walking or balance
  • dizziness
  • problems with hand-eye coordination
  • slurred speech
  • involuntary eye movements (nystagmus)
  • shaky hands
  • movement that’s awkward or poorly coordinated
  • difficulty with tasks involving fine motor skills

Factors that can raise the risk of brain and nerve effects when taking this drug include:

  • high doses of Banzel
  • taking other medications, such as other antiseizure drugs, that have brain and nerve effects
  • age, such as young children or older adults
  • liver problems or kidney problems
  • drinking excessive alcohol

What might help

To avoid problems with brain and nerve effects, your doctor will start you at the lowest dose possible and increase your dose slowly. Let your doctor know if you experience brain and nerve effects. If you do, they may adjust your dose or switch you to a different medication.

Take precautions to help prevent falls or injuries caused by dizziness or problems with balance. This could involve:

  • using handrails
  • removing throw rugs or other trip hazards
  • wearing supportive shoes
  • avoiding sudden or abrupt motions

Also, avoid driving or operating machinery until you understand how Banzel affects you. Check with your doctor if you have questions about driving while taking Banzel.

Suicidal thoughts and behaviors

Suicidal thoughts and behaviors were a rare side effect reported in studies of Banzel. But they can occur with any antiseizure medication.

Suicidal thoughts and behaviors may cause symptoms such as:

  • sudden or unusual mood changes
  • increased depression or anxiety
  • thoughts about harming yourself or others
  • taking actions to harm yourself or others
  • violent or angry actions
  • feelings of unrest, nervousness, and agitation
  • impulsive, aggressive behavior
  • episodes of panic
  • difficulty sleeping

Factors that can increase the risk of suicidal thoughts and behaviors when taking this drug include:

  • having a history of mental health conditions, such as bipolar disorder or anxiety
  • having a history of suicidal thoughts or actions
  • misusing alcohol or substances

What might help

To stay safe while taking Banzel, ask reliable family members, friends, and healthcare professionals for support. If you develop any unusual behavior, they could be the first to detect it and offer help.

If you have suicidal thoughts and behaviors during Banzel treatment, talk with your doctor right away. If your symptoms are life threatening, call 911. Or call your local emergency number to seek immediate medical treatment.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you are not in the same household, stay on the phone with them until help arrives.

Below is important information you should consider before taking Banzel.

Warnings

Banzel can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Banzel is a good treatment option for you.

Talk with your doctor about your health history before you take Banzel. Be sure to tell them if any of the following factors apply to you:

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.