Table 2:

Medications used to treat autism spectrum disorder behaviours and symptoms

MedicationTarget behaviourEvidenceOn- or off-labelAdverse events*
Atypical antipsychotic medications (i.e., aripiprazole risperidone)Irritability, aggressionMultiple, well-designed RTCs supporting their use69,75FDA indicationWeight gain, metabolic syndrome, gastrointestinal effects, sedation, akathisia, orthostatic hypotension, tachycardia, extra- pyramidal syndrome, neuroleptic malignant syndrome (rare)
Repetitive behaviours≥ 2 large RCTs support efficacy (although not a primary outcome measure)69,75Off-label
Serotonin reuptake inhibitorsRepetitive behaviour§1 unpublished and 1 published large RCT (fluoxetine, citalopram): no evidence for efficacy70Off-label, unless comorbid obsessive–compulsive disorderGastrointestinal effects, insomnia, agitation, disinhibition, dry mouth, headache, sexual dysfunction
Anxiety or depressionNone in autism, but multiple studies for pediatric anxiety disorders and depressionOn-label for anxiety disorders and depression
StimulantsADHD-like symptoms> 2 RCTs (methylphenidate) support its use76; smaller studies support longer-acting stimulantsOn-label for ADHDPoor appetite, weight loss, irritability, insomnia
AtomoxetineADHD-like symptoms**1 large, 1 small RCT support effectiveness77,78On-label for ADHDGastrointestinal effects, insomnia, orthostatic hypotension
α-agonistsADHD-like symptomsSeveral small RCT and open label studies in autism support efficacy79Clonidine: off-label; guanfacine: FDA indication for ADHD††Somnolence, hypotension, bradycardia, dry mouth, constipation, irritability
MelatoninInitial insomnia‡‡Cochrane meta-analysis, positive effect on initial insomnia compared to placebo80Not regulatedHeadache, dizziness and nausea (all rare outcomes)
  • Note: ADHD = attention–deficit/hyperactivity disorder, CI = confidence interval, FDA = US Food and Drug Administration, RCT = randomized controlled trial.

  • * Commonly reported adverse events. This list is not exhaustive.

  • Risperidone: effect size 1.2, p < 0.001; aripiprazole: difference in least square means: −7.9 (95% CI −11.7 to −4.1), p < 0.001.

  • Risperidone (Aberrant Behavior Checkliststereotypye) effect size: 0.8, p < 0.001; aripiprazole: Child Yale Brown Obsessive Compulsive Scale: difference in least square means: −3 (95% CI −4.3 to −1.6), p < 0.001.

  • § Citalopram: relative risk 0.969 (95% CI 0.61 to 1.51), p > 0.99.

  • Optimal dose methylphenidate: SNAP-IVADHD: d = 0.73, p < 0.001.

  • ** Atomoxetine: ADHD rating scale total score: difference in least square means: −6.7 (95%CI −10 to −3.4), p < 0.001.

  • †† Available in Canada through exceptional access programs.

  • ‡‡ Melatonin: sleep duration: Hedge’s g: 1.97 (95%CI 1.10 to 2.84); sleep onset latency: Hedge’s g: −2.42 (95%CI −1.96 to 2.98).