Researchers suggest the youngest children from the most vulnerable populations benefit most and show significant improvements towards expected growth for their age and sex, particularly for weight.
Poor nutrition in early childhood has both short and long term health effects and underlies around a third of all deaths in children aged under five years worldwide.
Antibiotics have been linked to significant height and weight gains among children from undernourished populations, but results have not always been consistent, researchers said.
The international team, including researchers from McGill University in Canada, set out to determine whether antibiotic treatment leads to improvements in growth in pre-pubertal children living in low and middle income countries.
They looked at changes in both linear growth (height) and ponderal growth (weight).
Researchers analysed the results of 10 trials involving 4,316 children aged one month to 12 years in seven low and middle income countries.
Children were generally below the age standardised average for height and weight, reflecting the spectrum of stunting and wasting malnutrition seen in these countries.
Differences in study design and quality were taken into account to minimise bias.
Overall, antibiotic treatment had a positive effect on both height and weight. The results show that antibiotics increased height by 0.04 cm/month and weight by 23.8 g/month.
After adjusting for age, effects on height were larger in younger populations and effects on weight were larger in African studies compared with other regions.
The exact reasons for the growth promoting effects of antibiotics remain unclear, said the authors, but may be due to resolving infections and altering gut microbes linked with impaired growth.
The growth gains "show the co-benefits of antibiotic treatment in high risk populations," they said.
However, they say more research is needed "to better understand the mechanisms involved."
Understanding how antibiotic use may increase growth in undernourished children is the important next step.
"Antibiotics, however, are not the most viable option for the treatment of malnutrition," the authors concluded.
The research was published in the British Medical Journal.