Risperidone: 7 things you should know
Medically reviewed by Carmen Fookes, BPharm. Last updated on April 16, 2020.
1. How it works
- Risperidone is used to treat psychotic symptoms. Experts are not sure exactly how risperidone works but suggest that its main effects are the result of it blocking both dopamine and serotonin receptors. Other effects may be due to blocking other neurotransmitter receptors.
- Risperidone belongs to the class of medicines called atypical antipsychotics. Atypical means it is less likely than older antipsychotics to cause side effects, and more likely to be effective in the treatment of symptoms such as lack of motivation and social withdrawal.
- Relieves psychotic symptoms such as hallucinations, delusions, confusion, disturbed thoughts and lack of insight or self-awareness.
- Used either alone or in combination with other medicines for the treatment of schizophrenia, acute mania or mixed episodes in bipolar disorder.
- Risperidone in small dosages may be also used to relieve irritability and symptoms of aggression, temper tantrums, and mood fluctuations in children with autistic disorder.
- Generic risperidone is available.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Drowsiness that may affect your ability to drive or operate machinery. Avoid alcohol.
- Extrapyramidal symptoms (such as restlessness, tremor, uncontrolled muscle contractions) are more likely at dosages greater than 6mg/day. Higher dosages have also not been associated with extra efficacy. Dosages for adolescents should be limited to 3mg/day to limit the risk of side effects.
- Other common side effects include anxiety, blurred vision, dizziness, gastrointestinal disturbances (nausea, vomiting, constipation, diarrhea, dyspepsia, pain), excessive salivation, tiredness, weight gain, and rash. Uncommonly, a reduction in the numbers of white blood cells, swallowing difficulty, priapism (sustained erections) and seizures may occur.
- A drop in blood pressure on standing, particularly during the initial dose titration period; dosage may need to be reduced then titrated up slowly. May not be suitable for people with known cardiovascular disease (history of a heart attack, angina, heart failure, or arrhythmia), stroke and people at risk of dehydration.
- An increase in blood sugar levels. People with a history of diabetes or at risk of diabetes should be monitored closely. May also cause undesirable changes in blood cholesterol and lipid levels and weight gain (on average, 4.3kg after 6 months of therapy).
- An increase in prolactin levels (risk is higher than with most other antipsychotics), leading to side effects such as impaired fertility, an absence of menstruation, unwanted lactation, breast enlargement in men, impotence, and decreased bone density. May not be suitable for people with a history of prolactin-dependent breast cancer.
- Potentially irreversible tardive dyskinesia, even with low dosages that have only been taken for a short period of time. Symptoms include facial grimacing, repetitive chewing, and tongue thrusting.
- May interact with some medicines. Dosage may need increasing when used with enzyme inducers such as carbamazepine or phenytoin; dosage may need reducing when used with enzyme inhibitors such as fluoxetine or paroxetine. See the prescribing information for risperidone for the full list of interactions.
- Should not be used for the treatment of dementia-related psychosis in elderly people because risperidone has been associated with a higher risk of death.
- Rarely, may cause Neuroleptic Malignant Syndrome; symptoms include high body temperature, muscle rigidity, and mental disturbances; discontinue immediately and seek urgent medical advice.
Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects
- Risperidone should be started at a lower dose initially then gradually titrated up depending on an individual's response and tolerability. Follow your doctor's instructions.
- Some people are more sensitive to the effects of risperidone and may need a more gradual increase in dosage - talk with your doctor if you are having trouble tolerating any side effects of risperidone.
- Splitting the daily dose into a morning and evening dose may help reduce symptoms of drowsiness in people with persistent drowsiness.
- Risperidone may cause drowsiness and you should not drive or operate machinery if risperidone has this effect on you. Avoid alcohol as it may potentiate the sedative effect of risperidone.
- Risperidone may be used long-term; however, a doctor should periodically reevaluate its effectiveness and monitor you for side effects. When used to delay relapse in people with schizophrenia, effectiveness in trials has lasted for at least 2 years (the duration of the trial).
- Risperidone may make you feel dizzy when going from a sitting or lying down position to standing. This may increase your risk of falls. Stand up slowly and remove any fall hazards from your home (such as loose rugs).
- Talk with your doctor if you develop any worrying side effects such as uncontrollable facial grimacing, restlessness, severe dizziness, or severe abdominal discomfort.
- Tell your doctor if you are intending to become pregnant and you are taking risperidone because your doctor may wish to change you to a different medication before you fall pregnant. Risperidone is incompatible with breastfeeding.
6. Response and Effectiveness
- Some effects may be noticed within a few days but it may take up to three to four weeks for the full effects of risperidone to be seen.
- Risperidone is metabolized to an active metabolite, 9-hydroxy-risperidone.
- Risperidone orally disintegrating tablets, risperidone oral solution, and risperidone tablets are all bioequivalent (this means that there is no difference in the extent to which they are absorbed and their effect).
Medicines that interact with risperidone may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with risperidone. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with risperidone include:
- antidepressants such as citalopram, escitalopram, or fluoxetine
- antipsychotics such as aripiprazole, clozapine or haloperidol
- CYP2D6 inhibitors or inducers, such as fluoxetine
- CYP3A4 inducers, such as carbamazepine, oxcarbazepine, phenytoin, rifampin, St John's Wort
- CYP3A4 inhibitors, such as clarithromycin, cyclosporine, fluconazole, ketoconazole, nefazodone, ritonavir, tamoxifen, verapamil
- diuretics, such as furosemide or hydrochlorothiazide
- heart medications, such as amlodipine, betaxolol, candesartan, carisprodol
- HIV medications, such as indinavir, nelfinavir, ritonavir, and saquinavir
- ipratropium or tiotropium
- kava kava
- magnesium sulfate
- medications used to treat Parkinson's Disease, such as cabergoline and levodopa
- opioids, such as alfentanil, fentanyl, buprenorphine, methadone, or oxycodone
- potassium chloride
- QT-prolonging medications, such as amiodarone, clarithromycin, domperidone, flupentixol, sotalol or voriconazole
Avoid drinking alcohol or taking illegal or recreational drugs while taking risperidone.
Note that this list is not all-inclusive and includes only common medications that may interact with risperidone. You should refer to the prescribing information for risperidone for a complete list of interactions.
- Risperidone. Revised 11/2019 Drugs.com. https://www.drugs.com/ppa/risperidone.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use risperidone only for the indication prescribed.
Copyright 1996-2021 Drugs.com. Revision date: April 16, 2020.
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