Pharmacology · Second-generation antipsychotics
Risperidone !
An atypical antipsychotic for schizophrenia, bipolar mania and irritability in autism; the atypical that raises prolactin the most.
Updated 2026-11-01
The figure shows risperidone in the human D2 receptor (fused to a lysozyme for crystallisation).
Mechanism of action
Risperidone blocks 5-HT2A and D2 receptors strongly, with α1 and H1 blockade. Its strong D2 blockade, also at the pituitary, raises prolactin markedly, and extrapyramidal effects increase with dose. Its active metabolite, 9-hydroxyrisperidone, adds to the effect.
- Risperidone blocks 5-HT2A and D2 receptors
- Psychotic and manic symptoms improve
- Pituitary D2 block: prolactin rises markedly
- Higher doses: more extrapyramidal effects
Pharmacokinetics
- Absorption
- Taken by mouth (tablets, solution, orally disintegrating tablets); long-acting injections exist
- Metabolism
- CYP2D6 converts it to the active 9-hydroxyrisperidone; the effect comes from both together
- Elimination
- Mainly in the urine; slower in older people and in kidney disease
Indications
- Schizophrenia
- Acute manic or mixed episodes of bipolar I disorder
- Irritability associated with autistic disorder (aggression, self-injury, tantrums)
Adverse effects
Common
- High prolactin: galactorrhoea, amenorrhoea, gynaecomastia, sexual dysfunction, reduced fertility
- Dose-related extrapyramidal effects and akathisia
- Orthostatic hypotension, especially at the start
- Weight gain and sedation
Contraindications
- Hypersensitivity to risperidone or paliperidone
Key interactions
- Fluoxetine, paroxetine and other CYP2D6 inhibitors
- Higher risperidone levels
- Carbamazepine and other enzyme inducers
- Lower levels of risperidone and its active metabolite
- Antihypertensives
- Additive hypotension
What is monitored
- Symptoms of high prolactin (menstrual changes, galactorrhoea, sexual problems)
- Weight, glucose and lipids
- Abnormal movements
- Blood pressure at the start and after dose changes
Administration and safety
- Oral and long-acting injectable forms are different products and are not interchanged one-for-one
- Look-alike name: risperidone can be confused with ropinirole; the label is read carefully
Nursing care
- Asks tactfully about breast changes, menstrual changes and sexual problems
- Checks lying and standing blood pressure and helps the patient stand up slowly (orthostatic hypotension, falls)
- Records weight, waist, glucose and lipids at baseline and during treatment
- Watches for fever, rigidity and confusion (neuroleptic malignant syndrome) and for abnormal movements; reports them at once
Pregnancy and breastfeeding
Newborns exposed in the third trimester may have extrapyramidal or withdrawal symptoms (agitation, abnormal tone, tremor, feeding problems); use weighs benefit and risk.
Test yourself
Think of the answer, then tap the question to see it.
Which atypical antipsychotic most often causes galactorrhoea and amenorrhoea?
Risperidone, through strong D2 blockade at the pituitary that raises prolactin.
Which enzyme converts risperidone to its active metabolite?
CYP2D6, producing 9-hydroxyrisperidone; CYP2D6 inhibitors such as fluoxetine raise risperidone levels.
Which behavioural problem in autism is a labelled use of risperidone?
Irritability: aggression, deliberate self-injury, tantrums and quick mood changes.
Related drugs
← Back to the class: Second-generation antipsychotics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - RISPERIDONE tablet (DailyMed (U.S. National Library of Medicine), 2026); Risperidone: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 19 (McGraw Hill, 2023).
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Representative model, for educational purposes only.