Health Library

Methsuximide (By mouth)

Methsuximide (meth-SUX-i-mide)

Treats absence seizures (also called petit mal seizures) after other medicines have been tried, but are unable to control the seizures. This medicine is an anticonvulsant.

Brand Name(s):

Celontin Kapseals

When This Medicine Should Not Be Used:

How to Use This Medicine:

Capsule

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
• This medicine may be used with other seizure medicines. Keep using all of your seizure medicines unless your doctor tells you to stop.
• If you notice that your capsules are not full or the contents have melted, call your pharmacist right away. The medicine may not work properly and should not be used.
• This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

If a dose is missed:

• Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine:

• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. This medicine melts easily, so be especially careful to not put it anywhere that is very hot, such as in a closed car, delivery vans, or near steam pipes.
• Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Make sure your doctor knows if you are also using other medicine for seizures (such as phenobarbital, phenytoin, Depakote®, Dilantin®, Keppra™, Luminal®, or Tegretol®).
• Do not drink alcohol while you are using this medicine.
• Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.

Warnings While Using This Medicine:

• Make sure your doctor knows if you are breastfeeding, or if you have kidney disease, liver disease, a blood or bone marrow disorder, or a history of depression.
• It is important to tell your doctor if you become pregnant while using this medicine. Your doctor may want you to join a pregnancy registry for patients taking a seizure medicine.
• Tell your doctor right away if you or your child feels unusually weak, starts bruising easily, has bleeding gums or nosebleeds, seems to be sick more often, has a fever, swollen glands, or a sore throat that will not go away. These could be a signs of a serious problem with the number of blood cells in your body.
• Tell your doctor right away if you or your child has a skin rash, muscle or joint pain, feels unusually tired, has a low-grade fever, or pain the chest that gets worse with breathing. These could be signs of a serious condition called systematic lupus erythematosus (SLE).
• Call your doctor right away if you or your child start to have a persistent cough, weight loss, night sweats, fever, chills, or flu-like symptoms such as a runny or stuffy nose, headache, blurred vision, or feeling generally ill. These may be signs that you have an infection.
• For some children, teenagers, and young adults, this medicine can increase thoughts of suicide. Tell your doctor or your child's doctor right away if you or your child start to feel more depressed or have thoughts about hurting yourself. Report any unusual thoughts or behaviors that trouble you or your child, especially if they are new or get worse quickly. Make sure the doctor knows if you or your child have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. Also tell the doctor if you or your child have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared. Let the doctor know if you, your child, or anyone in your family has bipolar disorder (manic-depressive) or has tried to commit suicide.
• Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
• This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
• Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments. Blood and urine tests may be needed to check for unwanted effects.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Blistering, peeling, or red skin rash.
• Bloody or cloudy urine.
• Fever, chills, cough, sore throat, and body aches.
• Increase in number of seizures.
• Problems with balance or walking.
• Red, swollen, or painful joints.
• Severe nausea, vomiting, or sleepiness.
• Sores or white patches in your mouth or throat.
• Swelling around the eyes.
• Unusual behavior or thoughts of hurting yourself.
• Unusual bleeding, bruising, or weakness.
• Unusual depression, aggressiveness, confusion, irritability, or other changes in behavior.

If you notice these less serious side effects, talk with your doctor:

• Blurred vision.
• Dizziness or drowsiness.
• Headache.
• Hiccups.
• Loss of appetite or weight loss.
• Mild nausea, vomiting, diarrhea, constipation, or stomach pain.
• Mild skin rash.
• Trouble with sleeping.

If you notice other side effects that you think are caused by this medicine, tell your doctor

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

Last Updated: 9/6/2024