Highlights
– Updated Cochrane review (2025) pooled 212 randomized trials (16,302 children/adolescents) evaluating methylphenidate vs placebo or no intervention.
– Methylphenidate may reduce teacher-rated ADHD symptoms (SMD -0.74; MD -10.6 on ADHD-RS) and improve teacher-rated general behaviour, but evidence certainty is very low.
– No clear effect on serious adverse events was detected (RR 0.80), while non‑serious adverse events were more frequent (RR 1.23).
– Most trials were short (mean duration ~29 days), at high risk of bias, and vulnerable to unblinding because typical stimulant side effects reveal allocation.
Background
Attention deficit hyperactivity disorder (ADHD) is among the most commonly diagnosed neurodevelopmental conditions in childhood and adolescence. Core features—persistent inattention, hyperactivity, and impulsivity—can impair academic performance, social functioning, and family life. Pharmacotherapy with stimulants, chiefly methylphenidate, is widely used. Despite long clinical experience, there remains debate about the magnitude and durability of benefit, and about the spectrum and frequency of harms. High-quality randomized evidence and transparent synthesis are essential to guide clinicians, families, and policy-makers.
Study design and methods (Cochrane update)
The 2025 Cochrane systematic review (Storebø et al.) updated comprehensive searches to March 2022 and included randomized clinical trials (RCTs) comparing methylphenidate versus placebo or no intervention in children and adolescents (≤18 years). Trials were eligible if ≥75% of participants had IQ >70. Primary outcomes were ADHD symptoms and serious adverse events; secondary outcomes included non‑serious adverse events, general behaviour, and quality of life.
Data from 212 trials (16,302 randomized) were synthesized: 55 parallel-group trials and 156 cross-over trials (plus mixed designs). Mean participant age was 9.8 years (range 3–18), male:female ratio ~3:1. The mean treatment duration was short (28.8 days). Risk-of-bias assessment rated 191/212 trials as high risk; deblinding due to stimulant side effects likely affected all trials. Trial Sequential Analysis (TSA) and GRADE were used to assess robustness and certainty of evidence.
Key findings
Magnitude of symptom improvement
Methylphenidate may improve teacher-rated ADHD symptoms compared with placebo or no intervention. Meta-analysis of 21 trials (1,728 participants) produced a standardized mean difference (SMD) of -0.74 (95% CI -0.88 to -0.61; I2 = 38%). This effect corresponds to a mean difference (MD) of -10.58 points (95% CI -12.58 to -8.72) on the ADHD Rating Scale (ADHD-RS; 0–72). The authors note a minimal clinically important difference of 6.6 points on the ADHD-RS; the observed mean change exceeds this threshold on average.
However, important caveats apply: most trials were brief (median/mean duration ~4 weeks), and the evidence was downgraded to very low certainty due to risk of bias, imprecision, and concerns about applicability.
Functional outcomes and quality of life
Teacher-rated general behaviour improved with methylphenidate (SMD -0.62; 95% CI -0.91 to -0.33; 7 trials, 792 participants), but heterogeneity was substantial. Quality of life was not clearly affected (SMD 0.40; 95% CI -0.03 to 0.83; 4 trials, 608 participants), with very low-certainty evidence and high between-study heterogeneity.
Serious and non‑serious adverse events
No convincing effect on serious adverse events was observed: pooled risk ratio (RR) 0.80 (95% CI 0.39 to 1.67; 26 trials, 3,673 participants), TSA-adjusted RR 0.91 (95% CI 0.31 to 2.68). The wide confidence intervals mean important benefit or harm cannot be ruled out.
Non‑serious adverse events were more common with methylphenidate: RR 1.23 (95% CI 1.11 to 1.37; 35 trials, 5,342 participants), TSA-adjusted RR 1.22 (95% CI 1.08 to 1.43). Typical non‑serious events include decreased appetite, sleep problems, abdominal pain, and headaches—events familiar from clinical practice.
Certainty of evidence and trial conduct
The authors rated the evidence for all outcomes as very low certainty using GRADE. Major contributors were: widespread high risk of bias across trials (191/212 high risk), short follow-up duration limiting inferences about sustained benefit and rare harms, substantial heterogeneity for some outcomes, and differential unblinding driven by stimulant side effects. Industry involvement was present in ~41% of trials (86/212), which may introduce additional concerns about reporting and selective outcome presentation.
Clinical interpretation and implications
How should clinicians and families interpret these findings? The pooled estimates suggest that methylphenidate produces clinically meaningful short-term reductions in teacher-rated ADHD symptoms and improved classroom behaviour for some children. The observed average change on ADHD-RS exceeded a commonly used minimal clinically important difference (6.6 points). However, the very low certainty of evidence means confidence in the magnitude and durability of effect is limited.
Safety data indicate non‑serious adverse events are more frequent with methylphenidate, a predictable finding given the pharmacologic profile of stimulants. The review did not find clear increases in serious adverse events, but CIs are wide and follow-up short—rare but serious outcomes (e.g., cardiovascular events, psychiatric complications) may not be detectable in these trials.
In clinical practice this supports an individualized, shared‑decision approach: for children with moderate-to-severe ADHD impairing school and social function, a trial of methylphenidate is reasonable when combined with careful monitoring. Important components include baseline assessment (cardiac history, growth, psychiatric comorbidity), structured follow-up for efficacy and adverse effects, and consideration of non-pharmacologic interventions (behavioural therapies, parent training) either before or alongside medication, in line with guideline recommendations.
Limitations of the evidence and review
Key limitations constrain the strength of conclusions:
- Predominance of short-duration trials (mean ~29 days) limits assessment of medium- and long-term efficacy, tolerability, and safety.
- High risk of bias across most trials, with particular concerns about blinding: stimulant side effects (e.g., insomnia, appetite loss) can unmask treatment allocation and bias subjective outcome ratings such as teacher or parent reports.
- Heterogeneity in trial design (parallel vs cross-over), outcomes measured, rating sources (teacher vs parent vs clinician), dosing regimens, and participant characteristics reduces generalizability.
- Industry funding in a substantial proportion of trials raises potential for selective reporting.
- Low representation of low- and middle-income settings and limited data on key subgroups (very young children, adolescents, comorbid conditions) restrict external validity.
Practical recommendations for clinicians
– Use shared decision-making: discuss potential short-term benefits, likelihood of common non‑serious adverse effects, and uncertainty about long-term outcomes.
– When initiating methylphenidate, document baseline symptoms, growth parameters, heart rate and blood pressure, sleep and appetite, and screen for psychiatric comorbidity. Arrange early follow-up (within weeks) to assess response and tolerability.
– Consider non-pharmacologic interventions (e.g., behavioural parent training, school accommodations) especially for preschool-aged children and as adjuncts for older children.
– For children with inadequate response or intolerable adverse effects, re-evaluate diagnosis, comorbidities, dosing/timing/formulation, and consider alternative agents or multidisciplinary approaches.
Priority areas for future research
The Cochrane authors highlight methodological priorities to improve confidence in treatment effects:
- Longer-term, adequately powered RCTs assessing sustained benefits, academic and psychosocial outcomes, growth and cardiovascular safety, and rare but important harms.
- Strategies to preserve blinding—use of active placebos that mimic adverse effect profiles might reduce differential unblinding and bias in subjective outcomes.
- Individual participant data meta-analyses to explore heterogeneity and identify subgroups most likely to benefit (age groups, ADHD subtypes, comorbidities).
- Pragmatic effectiveness trials and real-world safety registries to complement short explanatory RCTs and capture longer-term outcomes.
Conclusion
The 2025 Cochrane update synthesizes a large randomized evidence base and suggests methylphenidate may reduce teacher-rated ADHD symptoms and improve classroom behaviour in the short term, while increasing non‑serious adverse events. However, overall certainty of evidence is very low due to pervasive risk of bias, short follow-up, and potential unblinding. Clinicians should continue to use individualized, guideline-concordant care with close monitoring, and researchers should prioritize longer, rigorously blinded trials and subgroup analyses to clarify who benefits most and how to balance benefits against harms over the longer term.
Funding and trial registration
The Cochrane review (Storebø et al.) reports that 86 of 212 included trials (41%) were funded or partly funded by the pharmaceutical industry. The review searched trial registries and lists trial registrations including ClinicalTrials.gov identifiers: NCT02493777, NCT01798459, NCT00429273, NCT02520388, and NCT02139111 among others.
References
1. Storebø OJ, Storm MRO, Pereira Ribeiro J, et al. Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD). Cochrane Database Syst Rev. 2025 Dec 4;12(12):CD009885. doi: 10.1002/14651858.CD009885.pub4.
2. National Institute for Health and Care Excellence. Attention deficit hyperactivity disorder: diagnosis and management. NICE guideline [NG87]. 2018. (Accessed via NICE website.)
3. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013.
4. MTA Cooperative Group. A 14-month randomized clinical trial of treatment strategies for attention-deficit/hyperactivity disorder. Arch Gen Psychiatry. 1999;56(12):1073–1086.
