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Tridione Side Effects

Generic name: trimethadione

Medically reviewed by Last updated on Aug 2, 2023.

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

Applies to trimethadione: oral capsule, oral tablet chewable.


You should not stop using trimethadione suddenly. Stopping suddenly may make your condition worse.

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:

Common side effects may include:

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. 2001.

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.