• Basic Info
• Top Questions
• Clinical Info
• Interactions

Ethosuximide may increase the amount of other antiseizure medications in the blood. Such medications include phenytoin (Dilantin), mephenytoin (Mesantoin), and ethotoin (Peganone). These drugs must be monitored if they are used with ethosuximide to prevent the occurrence of dangerous side effects.

Ethosuximide may decrease the level of primidone (Mysoline) in the blood, which could lead to a loss of seizure control.

Valproic acid (Depakote, Depakene) may increase or decrease ethosuximide levels and must be used with caution.

Drugs other than those listed here may also interact with ethosuximide. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.

If you experience any of the following serious side effects, stop taking ethosuximide and seek emergency medical attention:

• an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);

• hallucinations or agitation;

• slurred speech or staggering walk;

• a rash;

• changes in vision;

• easy bruising or bleeding; or

• swollen or tender gums.

Other, less serious side effects may be more likely to occur. Continue to take ethosuximide and talk to your doctor if you experience

• nausea, vomiting, decreased appetite, constipation, or diarrhea;

• mild dizziness or drowsiness;

• tender or swollen glands;

• hiccups;

• lethargy and fatigue;

• irritability;

• euphoria;

• abdominal pain;

• headache;

• muscle twitches;

• increased facial hair;

• swelling of the breasts; or

• insomnia.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

Ethosuximide may cause serious blood problems. Notify your doctor immediately if you develop any of the following symptoms, which may be early signs of potential blood problems: fever, sore throat, rash, sores in the mouth, easy bruising, or red or purple bruising.