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Thioridazine Side Effects

Applies to thioridazine: oral tablet.


You should not use thioridazine if you have a heart rhythm disorder, a history of long QT syndrome, untreated or uncontrolled high blood pressure, very low blood pressure, or if you have drowsiness, slow breathing, weak pulse, or decreased alertness.

Thioridazine is not approved for use in older adults with dementia-related psychosis.

Thioridazine can cause a serious heart problem, especially if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV. Tell your doctor about all your current medicines and any you start or stop using.

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

High doses or long-term use of thioridazine can cause a serious movement disorder that may not be reversible. The longer you use thioridazine, the more likely you are to develop this disorder, especially if you are a woman or an older adult.

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 thioridazine: oral concentrate, oral suspension, oral tablet.

Nervous system

Drowsiness has been reported to subside with continuation of therapy or a reduction in dosage.[Ref]

Frequency not reported: Akathisia, akinesia, autonomic instability, drowsiness, dystonic reactions, extrapyramidal symptoms, headache, hyperactivity, lethargy, motor restlessness, neuroleptic malignant syndrome, opisthotonos, parkinsonism, pseudoparkinsonism, tardive dyskinesia, tremor[Ref]


Frequency not reported: Arrhythmia, bifid T/U wave, cardiac arrest, cardiac dysrhythmias, depression and inversion of the T wave, dose-related QT prolongation, ECG changes, edema, hypotension, irregular blood pressure, irregular pulse, pallor,

peripheral edema, polymorphic ventricular tachycardia/fatal polymorphic ventricular tachycardia, tachycardia, Torsades de pointes[Ref]

ECG changes are predicted to be reversible and are likely due to altered repolarization.[Ref]


Frequency not reported: Aggravation of psychoses, agitation, altered libido, altered mental status, behavioral effects, bizarre dreams, excitement, nocturnal confusion, psychotic reactions, restlessness, toxic confusional states[Ref]


Frequency not reported: Contact dermatitis, dermatitis, diaphoresis, erythema, exfoliative dermatitis, photosensitivity, progressive skin pigmentation, urticaria, urticarial skin eruptions[Ref]


Frequency not reported: Constipation, diarrhea, dry mouth, nausea, obstipation, paralytic ileus, parotid swelling, vomiting[Ref]


Frequency not reported: Breast engorgement, galactorrhea, inhibition of ejaculation, lactation, menstrual abnormalities/amenorrhea, urinary incontinence, urinary retention

Postmarketing reports: Priapism[Ref]


Frequency not reported: Agranulocytosis, anemia, aplastic anemia, eosinophilia, leukopenia, pancytopenia, thrombocytopenia[Ref]


Frequency not reported: Blurred vision, discoloration of exposed sclera and cornea, miosis, oculogyric crises, progressive conjunctival pigmentation, stellate/irregular-shaped opacities of anterior lens and cornea[Ref]


Frequency not reported: Fever, hyperpyrexia, paradoxical reaction, skin-eye syndrome, sudden death[Ref]


Frequency not reported: Muscular rigidity, systemic lupus erythematosus-like syndrome, trismus, torticollis[Ref]


Frequency not reported: Asthma, laryngeal edema, nasal stuffiness[Ref]


Frequency not reported: Biliary stasis, jaundice[Ref]


Frequency not reported: False positive pregnancy tests, gynecomastia[Ref]


Frequency not reported: Anorexia, weight gain[Ref]


Frequency not reported: Angioneurotic edema[Ref]


1. (2001) "Product Information. Mellaril (thioridazine)." Sandoz Pharmaceuticals Corporation

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.