Risperidone — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Risperidone?
Risperidone is a second-generation (atypical) antipsychotic used for schizophrenia, bipolar disorder, and irritability in autism spectrum disorder. This medication is funded by Pharmac under Special Authority for schizophrenia.
What is Risperidone Used For?
Used for schizophrenia, acute mania in bipolar disorder, and irritability/aggression in autism spectrum disorder. Long-acting injectable risperidone improves adherence in schizophrenia.
How Does Risperidone Work?
Blocks dopamine D2 and serotonin 5-HT2A receptors. Higher D2 affinity than quetiapine means greater extrapyramidal side effect risk. Also blocks alpha-1/2 adrenergic and histamine H1 receptors.
How to Take Risperidone
Once or twice daily, with or without food. Start 1–2 mg/day, titrate to 4–8 mg/day for schizophrenia. Long-acting injection (Risperdal Consta®) every 2 weeks. Continue oral risperidone for 3 weeks when starting the injection.
Common Side Effects of Risperidone
- Weight gain (less than olanzapine but significant)
- Sedation
- Extrapyramidal symptoms (more common than with quetiapine)
- Hyperprolactinaemia (sexual dysfunction, gynaecomastia, menstrual irregularities)
- Dizziness
- Metabolic effects
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Tardive dyskinesia
- Neuroleptic malignant syndrome
- QT prolongation
- Metabolic syndrome
- Stroke risk in elderly patients with dementia (significantly increased — not approved for dementia-related psychosis in NZ)
Drug Interactions
Risperidone may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Carbamazepine (reduces risperidone levels by 50%)
- Fluoxetine/paroxetine (increase levels)
- QT-prolonging medicines
- CNS depressants
New Zealand Prescribing Information
Risperidone (0.5–6 mg tablets; 1 mg/mL liquid — Risperdal® and generics) is funded under Special Authority. Long-acting Risperdal Consta® injection is also funded. Prolactin monitoring recommended for long-term users.
Frequently Asked Questions
Will risperidone affect my periods or sex life?
Risperidone can significantly elevate prolactin, causing irregular periods, galactorrhoea, and sexual dysfunction. Report these to your doctor — a prolactin check and dose review may be appropriate.
What is the long-acting injection for?
Risperdal Consta® given every 2 weeks improves adherence in schizophrenia for patients who have difficulty taking daily tablets consistently.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: