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Tridione Side Effects

Generic Name: trimethadione

Note: This document contains side effect information about trimethadione. Some of the dosage forms listed on this page may not apply to the brand name Tridione.

For the Consumer

Applies to trimethadione: oral tablet chewable

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

  • vision problems, droopy eyelids;

  • the first sign of any skin rash, no matter how mild;

  • unusual muscle weakness, trouble speaking or swallowing;

  • swelling in your feet or ankles;

  • low blood cell counts--fever, chills, flu-like symptoms, swollen gums, mouth sores, skin sores, rapid heart rate, pale skin, easy bruising, unusual bleeding, feeling light-headed;

  • lupus-like syndrome--joint pain or swelling with fever, swollen glands, muscle aches, chest pain, butterfly-shaped skin rash on your cheeks;

  • kidney problems--little or no urinating, painful or difficult urination, rapid weight gain;

  • liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • nausea;

  • drowsiness;

  • changes in mood or behavior; or

  • increased seizures.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to trimethadione: oral capsule, oral tablet chewable


Frequency not reported: Acneiform or morbilliform skin rash that may progress to exfoliative dermatitis or to severe forms of erythema multiforme, lupus erythematosus and lymphadenopathies simulating malignant lymphoma, pruritus (associated with lymphadenopathy and hepatosplenomegaly)[Ref]


Frequency not reported: Nausea, vomiting, abdominal pain, gastric distress, bleeding gums[Ref]


Frequency not reported: Vaginal bleeding, albuminuria[Ref]


Frequency not reported: Neutropenia, leukopenia, eosinophilia, thrombocytopenia, pancytopenia, agranulocytosis, hypoplastic anemia, fatal aplastic anemia[Ref]


Rare (less than 0.1%): Hepatitis[Ref]


Frequency not reported: Myasthenia gravis-like syndrome[Ref]

Nervous system

Frequency not reported: Drowsiness, fatigue, malaise, insomnia, vertigo, headache, paresthesias, precipitation of grand mal seizures, increased irritability[Ref]


Frequency not reported: Hemeralopia, photophobia, diplopia, retinal and petechial hemorrhages[Ref]


Frequency not reported: Hiccups, anorexia, weight loss, hair loss, changes in blood pressure, albuminuria[Ref]


Frequency not reported: Personality changes[Ref]


Frequency not reported: Epistaxis[Ref]


1. "Product Information. Tridione (trimethadione)" Abbott Pharmaceutical, Abbott Part, IL.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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