Does ADHD Medication Affect Children's Height?

This is one of the questions parents ask most. I wondered what answers are given to those who ask, so I looked at the sources, and what I saw bothered me.

Two kinds of answer are in circulation. One says "nothing will happen, do not worry about it." The other says "you are stopping your child's growth." Neither is any use to a family, because both try to close the question.

The honest answer is this: yes, there is a finding on this. And it is possible to separate what the finding says from what it does not say.

What the study found

The most comprehensive data in this field comes from the MTA study. The long-term follow-up of this study, in which children with a diagnosis of ADHD were followed for up to sixteen years (Swanson et al., 2017), reported two findings together:

• Long-term medication use was found to be associated with suppression of adult height.
• In the same group, long-term use was not found to be associated with an additional reduction in symptom severity.

The second finding is important too, and it is generally skipped. In other words the debate includes not only the question "what is the cost" but also "what is received in return for that cost."

Here a limit has to be drawn: this is a long-term observational follow-up. Those who went on taking medication and those who did not were not randomly assigned; who took how much was decided by families and doctors. In this kind of data, drawing cause and effect is limited. For example, children with more severe symptoms may have taken medication for longer, and other things affecting the picture may be at work.

The finding should be taken seriously, but it does not produce a decision by itself. The decision is made by looking at the child's own picture.

How big is the effect

The reported difference is at the level of a few centimeters on average. It varies from person to person and in some children it is not seen at all.

The other side that needs to be set beside it is this: untreated ADHD has consequences too. School achievement, accident risk, social relationships and the story the child builds about themselves are areas documented in long-term follow-ups.

So the decision is not made between a few centimeters and nothing. It is a balance with both sides, and it is not possible to put that balance in the same place for every family.

What the mechanism might be

It is not known for certain, but the path most dwelt on is appetite.

A known side effect of stimulant medications is suppressed appetite (Cortese et al., 2018). In a child who does not eat enough through the day, calorie intake drops and growth can be affected by this.

This can actually be counted as good news, because appetite can be worked on. Height is not something that can be directly intervened on; but how many meals are eaten and what is eaten can be intervened on.

What to monitor

The NICE guideline (NG87) recommends that in children being treated for ADHD, height and weight be measured regularly and plotted on the growth curve.

The concrete things for the family to follow:

• Height and weight measurement. Measured and recorded at regular intervals, in the same place and in the same way. A single measurement says nothing; the curve does.

• Meals. How many meals are eaten through the day, which meal is skipped.

• The hours of appetite. With stimulants appetite usually drops at the hours when the effect is highest and comes back in the evening.

• Energy and sleep. Inadequate nutrition can also show up as fatigue and irregular sleep.

• Signs other than growth. Weakness, frequent illness and more absent-mindedness in class can also be signs of inadequate nutrition.

I know nobody likes keeping records. But on the matter of height, memory is a particularly bad witness: nobody can notice a slow change over months with the eye. A graph notices it.

What happens on the eating pattern side

I want to open this subject separately, because the appetite question is not only about the medication.

In some children with ADHD there is already difficulty noticing hunger and fullness signals. In the glossary it is called body-signal blindness: understanding that you are hungry only when your hands and feet start shaking, and that you are full only when you are uncomfortable. When the appetite-suppressing effect of the medication is added to this, a child can end up who has not eaten at all through the day.

That is why leaving meals to the feeling of hunger does not work in these children. They need to be tied to the clock, and this is not rigidity; it is a system put in place of a missing signal.

I dealt with how the same pattern continues in adults in the article on nutrition in ADHD.

Questions to ask the doctor

Questions to write down before the check-up and put in your pocket:

• How often will my child's growth be measured, and will it be plotted on the curve?
• If appetite is dropping, what meal arrangements would you recommend?
• Would a change of dose or medication make a difference on this?
• Is a medication holiday suitable in our case, and if so how is it planned?
• If symptoms are under enough control, can we review the dose?
• In what situation will we reassess the treatment?

The last two questions are especially important. One reading of the MTA finding is this: staying at the lowest effective dose makes sense both for keeping the effect and for limiting side effects.

Do not stop on your own. Stopping the medication suddenly or lowering the dose on your own can cause symptoms to return and new problems at school. Telling your doctor about your worry is the right step; the decision needs to be made together. I dealt with the details of a medication holiday in the article on what happens if ADHD medication is stopped.

Practical things for appetite

• Give breakfast before the medication. The moment of highest appetite is usually the morning.
• Make the evening the big meal. Appetite comes back when the effect ends; using that window works.
• Calorie-dense, small-volume options. For a child who can eat only a little, the size of the plate can be discouraging.
• Make snacking visible. A plate standing on the table gets eaten far more than something standing in the cupboard. This is a rule that holds in ADHD for everything: what is not seen is ignored.
• Tie the meal to a reminder. There are children who find it hard to notice they are hungry; setting a clock is not coercion, it takes the place of the missing signal.

And I want to say this

What caught on me most while preparing this article was that the question put to families is always put in the form "medication or no medication." Yet what the MTA finding really points to is dose and duration.

Asking "are we on the lowest effective dose and when will we look again" instead of "shall we give it or not" is both more doable and more useful.

And it needs to be remembered that you do not make this decision once and finish. It is a decision that can be talked over again at every check-up.

I wrote about what can be expected from the treatment process as a whole in the article on ADHD medication treatment, and about how the picture looks in children in the article on ADHD symptoms in children.