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Risperidone

Prescription ·Strong evidence ·Reviewed May 2026

Prescription second-generation (atypical) antipsychotic approved for schizophrenia, bipolar mania, and irritability associated with autistic disorder. One of the most widely studied atypical antipsychotics with strong evidence for efficacy. Carries a notable risk of hyperprolactinemia and dose-dependent extrapyramidal symptoms at higher doses. Available as a long-acting injectable. Dosage must be determined by your prescribing physician.

Evidence tier
Strong
Indexed sources
10 1995–2025
Interactions
6
Category
Prescription
Read the sources → Compare profiles
What it's good for
  • Psychotic symptom reduction
  • Bipolar mania treatment5
  • Irritability reduction in autism9
  • Long-acting injectable option for adherence
  • Well-studied efficacy profile10
What to watch for
  • Hyperprolactinemia (gynecomastia, galactorrhea, amenorrhea)
  • Weight gain
  • Sedation
  • Known hypersensitivity to risperidone or paliperidone1,2
  • Parkinson's disease or Lewy body dementia

The bottom line

Evidence rating strong. Most-documented uses: psychotic symptom reduction, bipolar mania treatment, irritability reduction in autism. 10 sources indexed (1995–2025), with 6 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Potently antagonizes dopamine D2 and serotonin 5-HT2A receptors. Also has high affinity for alpha-1 and alpha-2 adrenergic and histamine H1 receptors. The active metabolite 9-hydroxyrisperidone (paliperidone) has similar receptor binding. High D2 affinity at higher doses increases the risk of EPS and prolactin elevation.

Class
Atypical Antipsychotic
Dosing

Dosing & protocol.

Common range
1–8 mg daily (as prescribed by your physician)
Recommended form
Tablet, orally disintegrating tablet, oral solution, or long-acting injectable

Can be taken with or without food. Risperdal Consta (LAI) given IM every 2 weeks requires 3-week overlap with oral supplementation at initiation.

Safety

Full safety detail.

Side effects

  • Hyperprolactinemia (gynecomastia, galactorrhea, amenorrhea)
  • Weight gain
  • Sedation
  • Extrapyramidal symptoms (dose-dependent)
  • Orthostatic hypotension
  • Dizziness
  • Metabolic effects

Contraindications

  • Known hypersensitivity to risperidone or paliperidone1,2
  • Parkinson's disease or Lewy body dementia
  • Concurrent use of drugs that prolong QT interval3,5
Interactions

Interaction records.

SeriousConflict

St. John's Wort

St. John's Wort induces CYP3A4, which metabolizes risperidone. Reduced risperidone levels can cause psychotic relapse.

Recommendation: Avoid combining. Loss of antipsychotic effect can be dangerous.

SeriousConflict

Cannabis (THC-Dominant)

THC-dominant cannabis can interfere with risperidone's relapse-prevention role in psychosis. Continued cannabis use in people with psychotic disorders is linked with higher relapse, nonadherence, and antipsychotic treatment failure. Risk is greatest with high-potency THC, frequent use, and a history of cannabis-related psychosis.

Recommendation: Avoid THC-dominant cannabis while taking risperidone for psychosis or mood stabilization. If you are using cannabis, tell your prescriber so they can monitor relapse risk, adherence, and side effects. Timing separation does not address the main risk.

SeriousCaution

Alcohol

Alcohol can increase risperidone-related drowsiness, slowed thinking, dizziness, and impaired coordination. Even when risperidone is less sedating than some antipsychotics, alcohol can still increase falls, unsafe driving, and poor judgment. Risk is higher during dose starts or increases, in older adults, and with other sedating medications.

Recommendation: Avoid alcohol while taking risperidone if possible. If you drink, do not drive or operate machinery, and do not take extra sedatives to sleep. Seek urgent help for severe confusion, fainting, slow breathing, or inability to stay awake.

InfoSynergy

NAC

NAC has human trial evidence as an adjunct to risperidone for negative symptoms of schizophrenia. The effect is not immediate and does not replace antipsychotic treatment, but it may modestly improve residual symptoms in some patients. Evidence is strongest for adjunctive use over weeks to months rather than as-needed dosing.

Recommendation: Do not use NAC as a substitute for risperidone. If you add NAC, keep risperidone unchanged unless your prescriber changes it, and track symptoms over several weeks. Stop and ask for guidance if NAC causes persistent stomach upset, wheezing, rash, or medication-adherence confusion.

InfoSynergy

Fish Oil

Fish oil, as a source of omega-3 polyunsaturated fatty acids, has been studied as an adjunct in recent-onset psychosis patients treated with risperidone. Trials suggest possible benefits for depressive/anxiety symptoms and brain white-matter measures, while broader schizophrenia omega-3 findings remain mixed. This is an adjunctive strategy, not an antipsychotic replacement.

Recommendation: Do not reduce or stop risperidone because you start fish oil. If you add fish oil, use a consistent product and track mood, anxiety, psychosis symptoms, and adverse effects over several weeks. Use extra caution if you also take blood thinners or high-dose NSAIDs, because fish oil can add bleeding tendency in those settings.

InfoSynergy

Methylfolate

Methylfolate has been studied as an adjunct in medicated schizophrenia patients with residual symptoms. Benefits appear selective and may depend on folate-pathway biology, baseline folate status, or elevated homocysteine rather than applying to everyone. It should not be used to replace risperidone or other antipsychotic treatment.

Recommendation: Consider methylfolate only as an adjunct and tell your prescriber before adding high-dose products. Do not change risperidone dosing on your own. Ask whether folate, B12, and homocysteine testing is appropriate, especially if you have poor diet, anemia, neuropathy symptoms, or known folate-pathway variants.

Search all 6 interaction records for Risperidone →

Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

2

Reviews & position papers

5

Reference material

3
Keep exploring

Deep dives & adjacent profiles.

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This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.

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