Dr Francine Ducharme and colleagues from McGill University in Montreal, Canada, found such treatment led to a 16% reduction in admissions.
The researchers said the findings highlighted the importance of appropriate treatment plans for patients, based on the severity of their disease.
Dr Ducharme and her team studied 406 children aged two to 17 years presenting to hospital with either moderate or severe asthma. Overall, 36% went on to be admitted.
Among those involved in the study, the median age was four years, 64% were male, while 88% had moderate asthma and 12% had severe asthma.
Systemic corticosteroids were given within 75 minutes in 50% of cases, and there were delays in 33% of cases. In 17% of cases, children failed to receive any systemic corticosteroid treatment.
Early administration of systemic corticosteroids reduced the odds of children being admitted to hospital by 40%.
Dr Ducharme said: ‘To be effective in preventing hospital admission, treatment with corticosteroids should be administered within 75 minutes of triage, regardless of age.
‘In fact, the earlier treatment is given within this timeframe, the more effective it is. Beginning early treatment reduces emergency department stay by almost 45 minutes.’