Those who grew up with food allergies are used to reading food labels and asking about ingredients at restaurants, but did you know that you can develop food allergies at any age? A new study, currently under review, finds that 52 percent of American adults with a food allergy developed one or more of their allergies after age 18.

The study, conducted by researchers from Ann and Robert H. Lurie Children’s Hospital of Chicago and Northwestern University Feinberg School of Medicine, surveyed 40,447 adults across the US. Unsurprisingly, shellfish and peanuts were the two most common adult allergies.

Although a large volume of anecdotal evidence has established the presence of adult allergy development, this study is the first to officially quantify the prevalence of allergy onset later in life. Anecdotal research suggests that life experiences like pregnancy or viral infection are common triggers for adult allergies.

Dr. Sharon Chinthrajah, an assistant professor at the Stanford University School of Medicine, notes that a food allergy differs from food intolerance in the sense that it presents itself with severe symptoms such as itching, hives, swelling, trouble breathing, or vomiting. Adult allergies also are unique as they sometimes present with oral allergy syndrome, a phenomenon not present in children with allergies where seasonal allergies can trick the body into an allergic reaction.

Some pollens have similarities to proteins found in fruits which can cause the body to think that they are ingesting pollen when consuming these raw fruits. For example, birch tree pollen has similarities to proteins found in peaches, apples, and cherries, so those with severe seasonal allergies can develop food allergies to these raw fruits later in life.

Just as adults can develop allergies after age 18, many people with childhood allergies also grow out of them as they age. Five percent of adults in the US have a food allergy, compared with about eight percent of children, and although this is still a relatively small proportion of the population, it does impact the day to day lives of many people and can be more difficult to manage if you didn’t grow up with the allergy. If you think you have developed an adult allergy, experts recommend seeking out an allergist for an official diagnosis.