Key messages
- Methylphenidate might reduce hyperactivity and impulsivity and might help children to concentrate. Methylphenidate might also help to improve general behaviour, but does not seem to affect quality of life.
- Methylphenidate does not seem to increase the risk of serious (life-threatening) unwanted effects when used for periods of up to six months. However, it is associated with an increased risk of non-serious unwanted effects like sleeping problems and decreased appetite.
- Future studies should focus more on reporting unwanted effects and should take place over longer periods of time.
What is attention deficit hyperactivity disorder (ADHD)?
ADHD is one of the most commonly diagnosed and treated childhood psychiatric disorders. Children with ADHD find it hard to concentrate. They are often hyperactive (fidgety, unable to sit still for long periods) and impulsive (doing things without stopping to think). ADHD can make it difficult for children to do well at school, because they find it hard to follow instructions and to concentrate. Their behavioural problems can interfere with their ability to get on well with family and friends, and they often get into more trouble than other children.
How is ADHD treated?
Methylphenidate (for example, Ritalin) is the medication most often prescribed to children and adolescents with ADHD. Methylphenidate is a stimulant that helps to increase activity in parts of the brain, such as those involved with concentration. Methylphenidate can be taken as a tablet or given as a skin patch. It can be formulated to have an immediate effect, or be delivered slowly, over a period of hours. Methylphenidate may cause unwanted effects, such as headaches, stomachaches and problems sleeping. It sometimes causes serious unwanted effects like heart problems, hallucinations, or facial 'tics' (twitches).
What did we want to find out?
We wanted to find out if methylphenidate improves children's ADHD symptoms (attention, hyperactivity) based mainly on teachers' ratings using various scales, and whether it causes serious unwanted effects, like death, hospitalisation, or disability. We were also interested in less serious unwanted effects like sleep problems and loss of appetite, and its effects on children's general behaviour and quality of life.
What did we do?
We searched for studies that investigated the use of methylphenidate in children and adolescents with ADHD. Participants in the studies had to be aged 18 years or younger and have a diagnosis of ADHD. They could have other disorders or illnesses and be taking other medication or undergoing behavioural treatments. They had to have a normal IQ (intelligence quotient). Studies could compare methylphenidate with placebo (something designed to look and taste the same as methylphenidate but with no active ingredient) or no treatment. Participants had to be randomly chosen to receive methylphenidate or not. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We found 212 studies with 16,302 children or adolescents with ADHD. Most of the trials compared methylphenidate with placebo. Most studies were small with around 70 children, with an average age of 10 years (ages ranged from 3 to 18 years). Most studies were short, lasting an average of around a month; the shortest study lasted just one day and the longest 425 days. Most studies were in the USA.
Based on teachers' ratings, compared with placebo or no treatment, methylphenidate:
- may improve ADHD symptoms (21 studies, 1728 children)
- may make no difference to serious unwanted effects (26 studies, 3673 participants)
- may cause more non-serious unwanted effects (35 studies, 5342 participants)
- may improve general behaviour (7 trials 792 participants)
- may not affect quality of life (4 trials, 608 participants)
Limitations of the evidence
Our confidence in the results of the review is limited for several reasons. It was often possible for people in the studies to know which treatment the children were taking, which could influence the results. The reporting of the results was not complete in many studies and for some outcomes the results varied across studies. Studies were small and they used different scales for measuring symptoms. And most of the studies only lasted for a short period of time, making it impossible to assess the long-term effects of methylphenidate. Around 41% of studies were funded or partly funded by the pharmaceutical industry.
How up to date is this evidence?
This is an update of a review conducted in 2015. The evidence is current to March 2022.