From the FDA Drug Label
OVERDOSAGE SECTION 10.1 Human Experience Premarketing experience included eight reports of acute RISPERIDONE overdosage with estimated doses ranging from 20 to 300 mg and no fatalities. In general, reported signs and symptoms were those resulting from an exaggeration of the drug's known pharmacological effects, i.e., drowsiness and sedation, tachycardia and hypotension, and extrapyramidal symptoms. One case, involving an estimated overdose of 240 mg, was associated with hyponatremia, hypokalemia, prolonged QT, and widened QRS. Another case, involving an estimated overdose of 36 mg, was associated with a seizure Postmarketing experience includes reports of acute RISPERIDONE overdosage, with estimated doses of up to 360 mg. In general, the most frequently reported signs and symptoms are those resulting from an exaggeration of the drug's known pharmacological effects, i.e., drowsiness, sedation, tachycardia, hypotension, and extrapyramidal symptoms. Other adverse reactions reported since market introduction related to RISPERIDONE overdose include prolonged QT interval and convulsions. Torsade de pointes has been reported in association with combined overdose of RISPERIDONE and paroxetine. 10. 2 Management of Overdosage For the most up to date information on the management of RISPERIDONE overdosage, contact a certified poison control center (1-800-222-1222 or www.poison. org). Provide supportive care including close medical supervision and monitoring. Treatment should consist of general measures employed in the management of overdosage with any drug. Consider the possibility of multiple drug overdosage. Ensure an adequate airway, oxygenation, and ventilation. Monitor cardiac rhythm and vital signs. Use supportive and symptomatic measures. There is no specific antidote to RISPERIDONE.
The symptoms of a Risperidone overdose include:
- Drowsiness and sedation
- Tachycardia and hypotension
- Extrapyramidal symptoms
- Prolonged QT interval and convulsions
- Hyponatremia, hypokalemia, and widened QRS in some cases
- Torsade de pointes in cases of combined overdose with paroxetine
- Seizure in some cases
Management of Risperidone overdose should include:
- Contacting a certified poison control center for the most up-to-date information
- Providing supportive care with close medical supervision and monitoring
- Ensuring an adequate airway, oxygenation, and ventilation
- Monitoring cardiac rhythm and vital signs
- Using supportive and symptomatic measures 1
From the Research
Risperidone overdose is a medical emergency that requires immediate attention, with symptoms including extreme drowsiness, rapid heartbeat, low blood pressure, QT prolongation on ECG, extrapyramidal symptoms, confusion, agitation, and in severe cases, seizures or coma. The management of risperidone overdose involves supportive care, including airway protection, IV fluids, cardiac monitoring, and activated charcoal if the overdose was recent (within 1-2 hours) 2.
Symptoms of Risperidone Overdose
- Extreme drowsiness
- Rapid heartbeat
- Low blood pressure
- QT prolongation on ECG
- Extrapyramidal symptoms (muscle stiffness, tremors)
- Confusion
- Agitation
- Seizures or coma (in severe cases)
Management of Risperidone Overdose
- Call emergency services (911) immediately
- Supportive care, including airway protection, IV fluids, and cardiac monitoring
- Activated charcoal if the overdose was recent (within 1-2 hours)
- Benzodiazepines may be used for agitation or seizures
- Hypotension is treated with IV fluids and sometimes vasopressors
- Anticholinergic medications like benztropine or diphenhydramine may be administered for severe extrapyramidal symptoms
According to the most recent and highest quality study 2, risperidone overdose causes minimal effects, with tachycardia and dystonic reactions being the main features of toxicity. Significant cardiac and other neurological features seem to be uncommon. The treatment of risperidone overdose is primarily supportive, with a focus on managing symptoms and preventing complications. Recovery typically occurs within 24-72 hours with appropriate supportive care, but complications can arise in severe cases or when combined with other substances 3, 4.