A new study has revealed that 15% of children who suffered severe, life-threatening allergic reactions can experience it the second time around just hours after the first episode.

Researchers at the Children's Hospital of Eastern Ontario (CHEO) Research Institute examined medical records of children admitted for allergic reaction.

Of the 484 patient records examined, 15% of the population had an incidence of biphasic reaction, and two thirds of this occurred within six hours since the first reaction.

Half of biphasic reactions were found to be serious and required intervention using epinephrine.

The June 22 study found in Annals of Allergy, Asthma & Immunology revealed that the biphasic reactions likely happen if the first episode of the allergic reaction was severe in nature and no treatment of epinephrine was given.

Furthermore, the reaction will be more severe with delayed treatment, according to the Science Daily report.

CBC reports that the goal of the research was to find out the prevalence of biphasic reactions and if there are interventions necessary to predict who is at a high risk of developing recurrent, delayed reactions.

Dr. Waleed Alqurashi, the study's first author, said that children who experienced an initial allergic reaction severe in nature should remain in the emergency department for some hours to allow for close observation.

"On the flip side, knowing what to look for helps to better utilize resources so that children with mild allergic reaction, who do not match any of the identified predictors can go home faster." Alqurashi said in the Science Daily report.

According to Alqurashi, in a news report from CBC, the most important thing parents should do is to treat allergic reactions immediately and seek medical help.

Anaphylaxis is a severe allergic reaction often associated with consumption of known allergens such as shellfish and peanuts. The reaction can progress to shock, causing breathing problems that can be fatal.