Growth on stimulant medication; clarifying the confusion:
Dr A Poulton, Western
Clinical School, Nepean
Campus, The University of
Accepted 22 March 2005
Arch Dis Child 2005;90:801–806. doi: 10.1136/adc.2004.056952
Aims: To get an overview of the studies of growth in height in children with attention deficit hyperactivity
disorder (ADHD) treated with stimulant medication, to establish the consistencies and to try to resolve the
Methods: Twenty nine studies were reviewed following a Medline search: 22 related to children, six to late
adolescents or adults, and one to children and adults.
Results: Children: Eleven studies gave results consistent with height attenuation on stimulant medication:
eight were longitudinal, one was cross-sectional, and two showed growth rebound on ceasing medication.
Studies with negative findings were inadequately powered (n=3), lacked controls or statistical analysis
(n=3), measured height velocity without reference to treatment duration (n=2), or used inappropriate
growth parameters (n=1), controls (n=1), or normative data (n=1). Late adolescents/adults treated with
stimulant medication in childhood: Two studies associated childhood gastrointestinal side effects with
attenuated late adolescent or adult height; all six cross-sectional studies had negative findings. The
methodologies varied widely but there was some consistency in the degree of attenuation shown in studies
with positive findings. The most sensitive methods analysed the changes in z-scores (standard deviation
scores) or calculated the height deficits from paired measurements taken before and after an initial period
of treatment with stimulant medication. The height deficit amounted to approximately 1 cm/year during
the first 1–3 years of treatment.
Conclusions: Further research is needed into the causal mechanisms, the rate of physical maturation, and
the long term implications for final stature.
observations, Safer and Allen published studies in the 1970s
showing early weight loss and growth in height that
remained slower than controls for the first three years of
treatment.1Rebound growth on ceasing medication was also
shown.2Safer and Allen’s work was followed by a spate of
studies, some replicating their results and others showing
little effect on growth in height, although weight loss on
starting stimulant medication has been a usual finding. As a
result of ongoing discrepancies in the published literature,
knowledge in this important area has advanced very little
over the past 30 years and this topic remains one of confusion
The purpose of this paper was to get an overview of the
studies of growth in height in children with ADHD, to
establish the consistencies, and to try to resolve the
discrepancies. The effect of stimulant medication on growth
in weight was not examined because it is more widely
accepted that stimulant medication may be associated with
transient weight loss, and because fluctuations in weight are
often regarded as less serious as weight can be regained later.
timulant medication was first suspected to have an
adverse effect on growth in height in children with
ADHD by a school nurse Evelyn Barr.1Following her
A Medline search up to September 2004 was conducted using
the keyword ‘‘growth’’ combined with ‘‘ADHD’’, ‘‘methyl-
phenidate’’, or ‘‘dexamphetamine’’. Reference lists of the
articles were also screened. Studies reviewed were all cohort
studies of children with ADHD treated with methylphenidate
or dexamphetamine, or of adults treated as children. Studies
were excluded if they had less than 10 subjects or lacked
sufficient details for some analysis of the methodology. Data
on pemoline were not included as this is used less frequently
due to the risk of adverse effects.
Studies were classified, analysed, and evaluated according
to the study design and whether the subjects were children or
Twenty nine studies met the selection criteria. There were 22
studies of children, six studies of adults or adolescents close
to their adult height, and one study that included both
children and adults. Some studies have been published in
two stages and therefore have two separate references. Seven
studies related only to boys, one only to girls, and the
remainder included both boys and girls or only specified
‘‘children’’. The adult studies consisted either exclusively or
predominantly of men.
Studies in children
Table 1 summarises 21 studies in children classified by the
study design. Nine of these gave results consistent with
statistically significant attenuation of growth in height on
stimulants and 12 had negative findings. In addition to these
there were studies by Safer and colleagues2and Klein and
colleagues26showing rebound growth on ceasing medication,
implying that on medication growth had been attenuated.
Dose of stimulant medication
The dose of methylphenidate or methylphenidate equivalent
(calculated by doubling the dose of dexamphetamine) for the
nine studies in table 1 showing statistically significant
attenuation ranged from 21.6 to 42 mg (median 31.4 mg).
For the 12 studies with negative findings, the range for the
nine which specified mean dosage was 18.4–34 mg (median
23.9 mg). Studies using lower doses of methylphenidate1 9
The confusion resulting from the discrepancies in the
literature has diverted attention from the important question
that follows on from this: what is the significance of the
period of poor growth that many children experience when
starting stimulant medication? There seems to be an
assumption among clinicians that for most children the
effect on growth is clinically unimportant, particularly when
balanced against a favourable response in controlling the
symptoms of ADHD. This may turn out to be correct, but
further research is needed to evaluate this assumption. The
effect of stimulant medication on growth needs to be studied
prospectively and over longer time periods looking into the
causal mechanisms, the rate of physical maturation, and the
long term implications for final stature.
I acknowledge Dr P Oakeshott for comments on the manuscript.
Competing interests: none
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