Thioridazine Side Effects
More frequently reported side effects include syncope, star-shaped cataract, epithelial keratopathy, dizziness, drowsiness, sedation, constipation, visual disturbance, nasal congestion, urinary retention, retinitis pigmentosa, increased serum prolactin, akathisia, xerostomia, and hypohidrosis. See below for a comprehensive list of adverse effects.
For the Consumer
Applies to thioridazine: tablets
Other dosage forms:
Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur while taking thioridazine:
Agitation; constipation; diarrhea; dizziness; drowsiness; dry mouth; enlarged pupils; jitteriness; nausea; stuffy nose; vomiting.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest or throat; swelling of the mouth, face, lips, or tongue; unusual hoarseness; wheezing); chest pain; confusion; decreased coordination; drooling; fainting; fast, slow, or irregular heartbeat; mask-like face; muscle spasms of the face, neck, or back; muscle weakness; new or worsening mental or mood problems; numbness of an arm or leg; prolonged or painful erection; restlessness; seizures; severe or persistent constipation; severe or persistent dizziness, drowsiness, or headache; shuffling walk; sleeplessness; stiff or rigid muscles; sudden shortness of breath or vomiting; swelling of the hands, ankles, or feet; symptoms of infection (eg, fever, chills, persistent sore throat); symptoms of liver problems (eg, yellowing of the skin or eyes; dark urine; pale stools; severe or persistent nausea, stomach pain, or loss of appetite); tremor; trouble urinating; twisting or twitching movements; uncontrolled muscle movements (eg, twitching of the face or tongue; loss of balance; uncontrolled movements of arms or legs; trouble speaking, breathing, or swallowing); unusual bruising or bleeding; unusual eye movements or inability to move eyes; unusual or excessive sweating; unusual tiredness or weakness; unusually pale skin; vision changes (eg, blurred vision).
For Healthcare Professionals
Applies to thioridazine: oral concentrate, oral suspension, oral tablet
Nervous system side effects including drowsiness have occasionally been reported. Pseudoparkinsonism and other extrapyramidal symptoms have infrequently been reported. Nocturnal confusion, hyperactivity, lethargy, psychotic reactions, restlessness, and headache have been reported extremely rarely.[Ref]
Drowsiness has been reported to subside with continuation of therapy or a reduction in dosage.[Ref]
Cardiovascular side effects including prolongation of the QTc interval have been reported. Prolongation of the QTc interval occurs in a dose related manner which has been associated with torsades de pointes type arrhythmias and sudden death. A case of acute hypotension and a case of massive edema have also been reported.[Ref]
Baseline ECG and serum potassium levels are recommend for patients being considered for treatment with thioridazine. Thioridazine is not recommended for use in patients with a QTc interval greater than 450 msec. It is recommended that serum potassium levels be normalized before initiation of therapy.
Once the patient is receiving thioridazine, periodic ECG's and serum potassium levels are recommended. Discontinuation of therapy is recommended if patients are found to have a QTc interval over 500 msec.[Ref]
Gastrointestinal side effects including dryness of the mouth, constipation, nausea, vomiting, and diarrhea have been reported. Obstipation, anorexia, and paralytic ileus has been reported with the use of phenothiazine derivatives.[Ref]
Ocular side effects including retinopathy and blurred vision have been reported. Miosis has been reported with the use of phenothiazine derivatives.[Ref]
Respiratory side effects including nasal stuffiness have been reported.[Ref]
Dermatologic side effects including pallor have been reported. Dermatitis and urticarial skin eruptions have been reported infrequently. Photosensitivity has been reported extremely rarely. Erythema, exfoliative dermatitis, and contact dermatitis have been reported with the use of phenothiazine derivatives.[Ref]
Endocrine side effects including galactorrhea, breast engorgement, amenorrhea, inhibition of ejaculation and peripheral edema have been reported. Menstrual irregularities, altered libido, gynecomastia, lactation, weight gain, edema, and false positive pregnancy tests have been reported with the use of phenothiazine derivatives.[Ref]
Other side effects including parotid swelling have been reported.[Ref]
Hematologic side effects including agranulocytosis have been report. Leukopenia, eosinophilia, thrombocytopenia, anemia, aplastic anemia, and pancytopenia have been reported with the use of phenothiazine derivatives.[Ref]
Hepatic side effects including individual cases of cholestasis, elevated transaminase levels, and clinical jaundice have been reported. Biliary stasis have been reported with the use of phenothiazine derivatives.[Ref]
Psychiatric side effects including agitation have been reported in patients receiving phenothiazine derivatives. A case report of thioridazine induced toxic psychosis has also been reported.[Ref]
Musculoskeletal side effects including tardive dyskinesia has been reported with the use of phenothiazine derivatives.[Ref]
Genitourinary side effects including ejaculatory problems (60% in a study of 57 male patients) have been reported. One third of these patients experienced retrograde ejaculation. Urinary incontinence and priapism have also been reported. Urinary retention been reported with the use of phenothiazine derivatives.[Ref]
General side effects including hyperpyrexia have been reported with the use of phenothiazine derivatives. Behavioral effects suggestive of a paradoxical reaction which included excitement, bizarre dreams, aggravation of psychosis and toxic confusional states have also been reported with the use of phenothiazine derivatives.[Ref]
Metabolic side effects include one case of exacerbation of diabetes which has been reported.[Ref]
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3. Margolis J "Massive edema induced by thioridazine (Mellaril): an unusual complication." J Am Geriatr Soc 20 (1972): 593-4
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16. Kotin J, Wilbert DE, Verburg D, Soldinger SM "Thioridazine and sexual dysfunction." Am J Psychiatry 133 (1976): 82-5
17. Price WA, Giannini AJ "Thioridazine and diabetes" J Clin Psychiatry 44 (1983): 469
It is possible that some side effects of thioridazine may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.
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