Some children who were told they have a peanut allergy may not react to peanuts anymore, according to a new study in the United States. The research found that specially trained doctors can use food tests to see if a child's peanut allergy has changed. However, doctors warn that these tests, called food challenges, must be done in hospital because they can cause dangerous allergic reactions.

Doctors perform a food challenge by giving the child a very small amount of peanut, then slowly giving a little more. They watch the child carefully for any problems, such as strong allergic reactions. In the study, about 12% of babies who took this test had a serious allergic reaction, known as anaphylaxis, but because they were in a hospital, they all received fast treatment and were safe.

The most important result is that some children who were once allergic to peanuts may no longer be allergic, but families should never try this at home. Only trained doctors can say if it is safe to test. More research will look at how often children's peanut allergies change and if this testing can help more families in the future.