SIDE EFFECTS: May cause drowsiness, stomach upset, loss of appetite, headache, irritability or fatigue. If any of these effects persist or worsen, contact your doctor promptly. This medication may increase sensitivity to sunlight. Notify your doctor if any of the following effects occur: seizures, blurry vision, fever, sore throat, unusual bleeding or bleeding, clumsiness, skin rash. An allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing, stomach pain. If you notice other effects not listed above, contact your doctor or pharmacist.

PRECAUTIONS: Tell your doctor your medical history, especially of: kidney problems, liver problems, blood disorders, eye problems, allergies (especially drug allergies). This drug may make you dizzy or drowsy. Use caution engaging in activities requiring alertness such as driving or using machinery. Limit alcohol intake because it can increase the dizziness or drowsiness effects of this medication. Because this medication may increase sensitivity to sunlight, avoid prolonged sun exposure. Use sunscreen and wear protective clothing when outdoors. Trimethadione is not recommended for use during pregnancy. Consult your doctor for details. It is not known if this medication passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Tell your doctor of all prescription and nonprescription medications you may use, especially of other drugs that cause drowsiness such as: sleeping pills, sedatives, tranquilizers, anti-anxiety drugs, narcotic pain relievers (e.g., codeine), psychiatric medicines, other anti-seizure medications, muscle relaxants, antihistamines that cause drowsiness (e.g., diphenhydramine). Check the labels on all your medicines (e.g., cough-and-cold products) because they may contain drowsiness-causing ingredients. Ask your pharmacist about the safe use of these products.

Report Problems to the Food and Drug Administration You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088. Need help identifying pills and medications? Use the pill identifier tool on RxList.