Childhood allergies to milk and eggs appear to be harder to outgrow than in the past, U.S. researchers said on Wednesday.
While they were often outgrown by age 3 two decades ago, such allergies often persist into late childhood, researchers at Johns Hopkins Children’s Center in Baltimore, Maryland, report in two studies in the Journal of Clinical Immunology.
“The bad news is that the prognosis for a child with a milk or egg allergy appears to be worse than it was 20 years ago,” Dr. Robert Wood, health of allergy and immunology, said in a statement.
“Not only do more kids have allergies, but fewer of them outgrow their allergies, and those who do, do so later than before.”
Wood and colleagues examined medical records of more than 800 children with milk allergies and nearly 900 with egg allergies over a 13-year period.
Among children in the study with milk allergies, they found that by age 4, less than 20 percent of them had become able to tolerate milk, and by age 8, only 42 percent had outgrown the allergy.
That compared with prior studies, which suggested 75 percent of children would overcome their milk allergies by age 3.
The researchers found a similar trend with egg allergies. Just 4 percent outgrew this allergy by age 4, and just 37 percent outgrew it by age 10.
Many of these children eventually did outgrow their allergies, however, with 79 percent of the milk allergy group and 68 percent of the egg allergy group outgrowing their allergies by age 16.
And the studies found that some children were able to lose their allergies during adolescence, suggesting that pediatricians should keep testing older children.
The researchers said their findings may reflect the fact that they tend to see kids with more severe allergies. They also believe food allergies today are more aggressive but they do not know why.
“Our impression is that the disease is behaving differently than it did before,” Wood said in a telephone interview.
Milk allergy is the most common childhood allergy, affecting 2 percent to 3 percent of young children. Egg allergy is the second most common, affecting 1 percent to 2 percent of young children, the researchers said.