Generations of children have been told not to drink coffee because it will stunt their growth. It is one of the most familiar pieces of coffee folklore in the world, and it still shows up constantly in search suggestions. The short answer is that there is no scientific evidence that coffee makes children shorter. But the myth did not come from nowhere, and there are real, evidence-based reasons for children and teenagers to be careful with caffeine. They just are not about height.
Where the idea probably came from
For coffee to stunt growth, it would have to interfere with how bones grow and strengthen during childhood and adolescence, or seriously impair a child's nutrition during those years. Those are testable claims, and researchers have looked at the most plausible route, bone mineral, directly.
The scientific thread behind the worry is calcium. Caffeine was found to slightly increase the amount of calcium lost from the body, and calcium is essential for bone. From there, it was a short leap to the idea that coffee weakens growing bones and so limits growth. The research below tests each step of that chain.
How big is caffeine's effect on calcium?
The most careful measurement comes from Barger-Lux and Heaney[1], who analysed 560 calcium balance studies in 190 women aged about 35 to 69. A calcium balance study precisely tracks calcium going in through food and coming out of the body, so it shows whether the body is gaining or losing calcium overall.
They found that for every 177.5 ml serving of caffeinated coffee, calcium balance was more negative by about 4.6 mg a day. The association came from the input side, both calcium intake and the efficiency of calcium absorption, and it did not appear to be larger in people with low calcium intakes or in older women. The authors calculated that the effect could be offset by increasing calcium intake by about 40 mg for every cup of coffee.
So caffeine's effect on calcium is real but very small, and easily compensated for with a little more calcium, which means a coffee made with milk arguably carries its own offset. These were adult women, not children, but the size of the effect is useful context.
What happens to teenagers' bones?
The question that matters for the myth is whether caffeine affects bone development in young people. The Penn State Young Women's Health Study addressed this directly. Lloyd and colleagues[2] followed 81 non-Hispanic white girls from age 12 to 18, averaging six years of prospective diet records, and measured total body bone mineral gain and hip bone density at 18 using DXA scans.
The girls were grouped by caffeine intake: less than 25 mg a day, 25 to 50 mg, and more than 50 mg. There were no significant differences between the groups in total body bone mineral gain from 12 to 18, or in hip bone density at 18. The highest caffeine group did consume more sugar, and the lowest caffeine group drank more milk, but these differences were not associated with differences in body measurements or bone gain. The authors concluded that caffeine at the levels consumed by these teenagers was not correlated with adolescent bone gain.
It is worth noting that caffeine intake in this group was low, averaging 77 mg a day even in the highest group, which is less than one strong coffee. The study cannot say much about teenagers who drink several large coffees or energy drinks daily.
A larger, more recent answer for children
Cui and colleagues, in PLoS One[3], combined two approaches. Using US national survey data, they compared bone mineral density in children and adolescents with the highest and lowest quarters of caffeine intake, and found no significant differences at the femoral neck, total femur or spine. They then used Mendelian randomisation, a method that uses genetic variants associated with coffee or caffeine intake as a natural experiment, and found no causal relationship between coffee consumption or caffeine intake and total body bone mineral density in children and adolescents.
The authors noted that more studies are needed on long-term effects of early caffeine exposure, but on current evidence, neither observational data nor genetic analysis supports caffeine harming bone density in young people.
What about bones later in life?
In adults, the picture is mixed but not dramatic. Hallström and colleagues[4] followed 61,433 Swedish women for about two decades, during which 14,738 had a fracture and 3,871 had a hip fracture. Higher coffee consumption was not associated with a higher rate of fractures of any type or of hip fracture. Women drinking four or more cups a day had 2% to 4% lower bone density than those drinking less than one cup, but that did not translate into more fractures.
A meta-analysis by Lee and colleagues, in Bone[5], pooled 15 studies with 253,514 participants. It found a modestly higher fracture risk at the highest coffee intake in women, a relative risk of 1.14, and a lower risk in men, 0.76. In women, the estimated risk was 1.02 at two cups a day and 1.54 at eight cups a day. These are adult findings, relevant to heavy consumption over many years, and they say nothing about children's height.
The difference between men and women in that meta-analysis is not explained, and the authors called for better studies to confirm it. It may reflect differences in bone biology, in calcium intake, or in the other habits that travel with heavy coffee drinking. What the two adult studies agree on is that any effect of coffee on bone appears at high intakes over decades, and that the Swedish women's slightly lower bone density did not lead to more fractures. None of that supports the idea of a meaningful effect from moderate caffeine in childhood.
Why no study shows coffee affects height
We did not find any study showing that coffee or caffeine reduces height in children, and the research above explains why such an effect would be unlikely. Caffeine's influence on calcium is tiny and easily offset, and studies in teenagers and children found no effect on bone development. Height depends mostly on genes and on adequate nutrition and health during childhood, none of which a moderate amount of caffeine meaningfully changes.
There is one indirect route by which coffee drinks could matter: if sweet coffee drinks or soft drinks replace milk and nutritious food in a child's diet. In the Penn State study, lower caffeine intake went along with more milk. That is a question about what a drink displaces rather than about caffeine itself.
The real reasons children should be careful with caffeine
Although the growth myth does not hold up, there are good reasons for caution. A review by Temple, in the Journal of the American Academy of Child and Adolescent Psychiatry[6], concluded that typical, moderate caffeine consumption in children and adolescents appears relatively safe, but that higher doses, above 400 mg, can cause physiological, psychological and behavioural harm, particularly in children with psychiatric or cardiac conditions. The review also noted that safety recommendations are based on decades-old data collected mostly in adults, and that marketing of highly caffeinated products to young people has increased.
Sleep is a particular concern. A review of caffeine and sleep by Roehrs and Roth[7] noted that children and adolescents, despite lower weight-adjusted caffeine intake, experience sleep disturbance and daytime sleepiness associated with their caffeine use. For growing children, adequate sleep matters for health, learning and mood, so caffeine that disrupts sleep is a more realistic concern than anything to do with bones.
Mental health is another. In a large cohort of English secondary school children, Richards and Smith[8] found that higher total weekly caffeine intake was associated with more anxiety and depression after adjusting for other factors, although the cross-sectional design could not establish cause. And heavy caffeine intake can drive headaches: Hering-Hanit and Gadoth[9] described 36 children and adolescents with daily headaches linked to heavy cola consumption, most of whom became headache-free after gradually cutting down.
How much caffeine is reasonable for young people?
There is no single universal limit. A comprehensive review for Health Canada by Nawrot and colleagues[10] concluded that healthy adults could consume up to 400 mg a day without adverse effects, identified children as an at-risk group who may need specific advice, and suggested children consume no more than 2.5 mg of caffeine per kilogram of body weight per day. For a 30 kg child, that would be 75 mg; for a 50 kg teenager, 125 mg.
Those figures give a sense of proportion. When McCusker and colleagues[11] measured specialty coffees from coffee shops, a 16-ounce brewed coffee averaged 188 mg of caffeine, more than double the suggested limit for a 30 kg child in a single cup.
Coffee drinks, 3-in-1 sachets and the sugar question
In the Philippines, children and teenagers are more likely to meet coffee as a sweet drink than as black coffee: a 3-in-1 sachet, a milky iced coffee, or a café frappé topped with cream. For growth and health, the sugar in those drinks deserves at least as much attention as the caffeine. The Penn State study found that the highest-caffeine group of teenage girls also ate the most sugar, and the lowest-caffeine group drank the most milk, a reminder that caffeinated drinks often travel with sugar and can crowd out more nutritious choices.
None of the studies here were designed to separate the effects of sugar from caffeine in young people, so we cannot put a number on it. But from a practical standpoint, a sugary coffee drink that replaces a glass of milk or a meal is a more plausible threat to a child's nutrition than the caffeine itself. The concern for young people is less about an occasional small coffee and more about large or frequent doses, often combined with sugar and taken late in the day.
What about a small coffee, or decaf?
Families often ask whether a small, milky coffee at breakfast or a weekend café treat is a problem. The evidence reviewed here gives no reason to think an occasional small coffee harms a healthy child's growth or bones. The review by Temple[6] found typical moderate caffeine intake in young people relatively safe, with harm concentrated at much higher doses and in children with psychiatric or heart conditions. The sensible questions are how much caffeine is in the drink, how late in the day it is, how much sugar comes with it, and whether it is becoming a daily habit that affects sleep.
Decaf removes most, though not all, of the caffeine: McCusker and colleagues[12] measured between 0 and 13.9 mg in 16-ounce decaf coffees from different outlets. That takes care of the sleep and anxiety concerns for most children while keeping the ritual. It does nothing about sugar, so a sweet decaf frappé is still a sweet drink.
The limits of this evidence
The best study of teenage bone gain was small, involved only white girls, and covered low caffeine intakes. The genetic and survey analysis is larger but cross-sectional and genetic, not a trial. The calcium balance and fracture studies were in adults. There are no long-term trials of caffeine in children, for obvious ethical reasons, and research on the effects of heavy caffeine intake in young people, especially from energy drinks, is still developing.
The bottom line
Coffee does not stunt your growth. Caffeine has a small effect on calcium that is easily offset, and studies in teenagers and children found no link between caffeine and bone development. The better reasons to limit caffeine in young people are its effects on sleep, its association with anxiety and headaches at higher intakes, and the sugar that often comes with it in café drinks and soft drinks.
For children and teenagers, keeping caffeine low, avoiding it late in the day, steering clear of energy drinks, and not letting sweet coffee drinks replace milk and meals is consistent with the evidence. For adults, see our article on how much caffeine is safe, and for caffeine's effects on anxiety in young people and adults, our article on caffeine and anxiety. A paediatrician is the right person to advise on an individual child, especially one with a heart condition, anxiety or sleep problems.