What risperidone 0.5 mg (sold as Sizodone) does — and does not do — for autistic children

A meta-analysis of 41 studies found risperidone consistently reduced irritability, hyperactivity, lethargy, inappropriate speech and stereotypic behaviour in autistic children aged 2 to 17, over both short and longer periods. It also found a consistent link with weight gain and increased waist circumference. No study looked at the 0.5 mg dose or the Sizodone brand in isolation — 0.5 mg is simply a common starting or low maintenance dose.

Published 14 September 2026 · 5 min read

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What is it?: Sizodone is one Indian brand name for risperidone, an antipsychotic medicine approved to reduce irritability — tantrums, aggression and self-injury — in autistic children. The research looks at risperidone the drug, not at any particular brand or at the 0.5 mg tablet on its own.
Why does it matter?: If a doctor has suggested risperidone for your child, this is the evidence on what it tends to change (distressing behaviour, not autism itself) and what it tends to cost (appetite, weight and sedation), so you can weigh both sides of that trade with the prescriber.
When is it relevant?: This becomes relevant when aggression, self-injury or explosive meltdowns are severe enough that they are hurting your child or blocking therapy and school, and medication has come up as an option alongside behavioural support.

At a glance

Sample size: 41 studies pooled from 2,459 screened articles; participants aged 2-17, mean age 8.1 years, 78% male
Demographics: Autistic children and adolescents aged 2-17 (mean 8.13 ± 2.68 years), 78.28% male, across open-label, double-blind and cross-sectional studies
Key outcome: Risperidone reduced irritability and the other four ABC domains versus both baseline and placebo, short and long term; the earlier RUPP randomised trial found a 57% reduction in tantrums, aggression and self-injury versus 14% on placebo. Weight gain and increased waist circumference were consistently associated with use.
Methodology: PRISMA-registered systematic review and meta-analysis of 41 risperidone studies in autism, pooling change on the five Aberrant Behaviour Checklist subscales plus weight and waist circumference, with Jadad quality scoring and Cochrane risk-of-bias assessment. Supporting sources include a systematic review of risperidone's effects on cognition and reporting on the landmark RUPP trial.
Researchers: A. M. Pereira, B. J. M. Silva, B. C. Araújo, J. M. D. Almeida
Institutes: Current Neuropharmacology (PMC8206457), PROSPERO registration CRD42019122316

Limitations:

No study isolated the 0.5 mg dose or the Sizodone brand; trial doses were set by body weight and typically ranged higher, so these results describe risperidone in general
24 of the 41 pooled studies were open-label rather than blinded, and 19 were judged to carry a high risk of bias, mostly from weak randomisation
Most follow-up ran only 8 to 24 weeks, so effects and harms beyond a few months are thinly evidenced
Cognitive effects were studied only in small, short trials and remain unresolved
Benefits generally fade when the medicine is stopped, and not every child responds

What this research found

Across 41 pooled studies, risperidone lowered scores on all five Aberrant Behaviour Checklist domains — irritability, hyperactivity, lethargy, inappropriate speech and stereotypic behaviour — compared with both baseline and placebo.
The reduction in irritability was larger with longer use, while the gains for inappropriate speech, lethargy and stereotypic behaviour were strongest in the first eight weeks.
In the randomised trial that led to FDA approval, 57% of children had reduced tantrums, aggression and self-injury on risperidone versus 14% on placebo, and roughly 70% of responders were still improved six months later.
Weight gain and increased waist circumference were consistently associated with risperidone — children in earlier trials gained around 6 pounds in eight weeks — alongside drowsiness, hormonal changes and, rarely, involuntary movements.
Clinicians quoted in the reporting describe the drug as acting on distress and explosive behaviour rather than on autism itself; it is not a cure and does not reach the core features.

What this means for caregivers

If irritability, aggression or self-injury is the problem, this is one of the better-evidenced medication options, and the change is often visible within weeks rather than months.
It is not a treatment for autism. Social communication needs and the need for therapy do not go away, though calmer behaviour can make therapy and school accessible in a way they were not before.
The appetite and weight effect is predictable enough to plan for: ask the prescriber at the start how weight, waist measurement and metabolic bloods will be tracked, and how often.
A 0.5 mg tablet is usually a starting or low-dose step. Specialists quoted here favour the lowest workable dose, with periodic reviews of whether it is still needed.

Important caveats

This summary is about risperidone as a molecule. Sizodone is one brand of it, and no study here tested that brand, or the 0.5 mg dose, separately — dose in the trials was set by the child's weight.
More than half the pooled studies were open-label and 19 carried a high risk of bias, so the size of the benefit is less certain than its direction.
Most evidence covers 8 to 24 weeks. What happens over years — to growth, metabolism and cognition — is much less well studied.
Behaviour tends to return when the medicine is stopped, and a meaningful minority of children do not respond at all.
Never start, stop, change or split a dose on your own. Risperidone needs a prescriber monitoring your particular child.

Sources

Effects of Risperidone in Autistic Children and Young Adults: A Systematic Review and Meta-Analysis — Current Neuropharmacology, PMC8206457
The Effects of Risperidone on Cognition in People With Autism Spectrum Disorder: A Systematic Review — Cureus, PMC10507658
Risperidone use in children with autism carries heavy risks — Emily Anthes, 2014, The Transmitter (Spectrum)