Symptoms of food-induced anaphylaxis in infants are less severe than in toddlers and older children, a new study suggests.

Anaphylaxis is defined as a reaction that involves multiple systems in the body or a presentation with significant cardiac or respiratory symptoms. The latest guidelines from the National Institute of Allergy and Infectious Diseases, released in January 2017, recommend that infants should be introduced to peanut-containing foods between four and six months of age. These guidelines are a major shift from previous recommendations to avoid early introduction of peanut-containing products.

"We found that infants, unlike older children, have a low-severity food-induced anaphylaxis, which should come as reassuring news to parents who are about to introduce their baby to potentially allergenic foods like peanuts," said lead author Waheeda Samady from the Northwestern University Feinberg School of Medicine in the US.

"Since early introduction of peanuts is now encouraged by national guidelines, it is understandable that parents might be fearful of triggering a serious reaction," Samady added. For the study, published in the journal Annals of Allergy, Asthma and Immunology, the team analysed data from 350 cases which included 47 infants, 43 toddlers, 96 young children and 171 school-aged children. The analysis showed that 89 per cent of the infants presented with gastrointestinal symptoms more frequently than any other age group.

Vomiting, in particular, was present in 83 per cent of infants. Almost 94 per cent of infants and 91 per cent of toddlers presented with skin involvement more often than school-aged children. Hives was the most common skin manifestation found in 70 per cent of infants, the researchers said. Any respiratory symptoms including cough were more common in older age groups (17 per cent in infants versus 44 per cent in young children and 54 per cent in school-aged children). The researchers also said that this result is a welcoming news for parents who want to introduce different kinds of food to their baby early.