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It is very important to tell your doctor if you think you are having side effects from your seizure medicine(s). Once your doctor knows about the side effects, he or she can lower the dosage of your current medicine, change how you take it through the day, or start you on a new seizure medication. The best course of action depends on how serious the side effect is and whether or not the medicine has been helping to prevent your seizures.

If you tell your doctor that you have unacceptable side effects from your seizure, and lowering the dosage is not an option, then he or she should start another seizure medicine and guide you through the transition. In this case, you will probably need to continue taking both your current medication and the new medication until your dose of the new drug is strong enough to control your seizures. Alternatively, the dose of the first drug may be slowly lowered while the dose of the new drug is increased.

On the other hand, your current drug may need to be stopped quickly by your doctor if it is causing very serious side effects.

Most of the time, side effects are mild and short-lasting and can be treated by properly adjusting the dosage (the amount taken and the time of each dose).

Common side effects from seizure medicines

You may experience some fatigue, abdominal discomfort, dizziness, or blurred vision during the first weeks of taking these medicines. But if the medication is started at a low dose and increased slowly, and if you are aware of what to expect, these effects are usually tolerable. They probably will stop after several weeks or months, as tolerance develops.

Different seizure medicines tend to produce different types of side effects. To find out what effects are most common with your medication, look it up at www.epilepsy.com/epilepsy/seizure_medicines. Just because a certain effect is common with your medication, however, does not mean that you will experience it. Many people have few or no problems with side effects.

Uncommon side effects from seizure medicines

Allergic reactions to seizure medicines are infrequent but they do occur, usually within the first 6 months of starting the medication. The most common type of allergic reaction is a rash.

Unpredictable side effects that are not related to the dosage or level of medication in the blood can also occur and are called “idiosyncratic’. These can range from mild to potentially life threatening, and can include:

• Rash
• Inflammation or failure of the liver or pancreas
• A serious reduction in the number of white blood cells, which are needed to fight infection
• A serious reduction in the number of platelets in the blood, which are needed to control bleeding

Contact your doctor immediately if a rash or troublesome itchiness develops after a new medication is prescribed. If you are taking more than one medication, the one that was started most recently has probably caused the rash, although rashes may also be caused by a variety of unrelated factors. Most rashes usually disappear quickly if the medication is stopped, but you should always tell your doctor right away if a rash begins, because occasionally they can be very serious, and not stop the medicine unless instructed to by the doctor.

Also contact your doctor immediately if you experience sores, blisters, or ulcers in your mouth; skin blisters; excessive bleeding; abdominal pain and tenderness; hair loss; fever; unusual infections; or other unusual symptoms while taking a seizure medicine.

For more information:

• Side Effects
• Seizure Medicines

Topic Editor: Mary Jo V. Pugh, PhD, RN and Steven C. Schachter, MD.
Last Reviewed: 7/30/08