PITTSBURGH (KDKA) — Emergency room visits because of food allergies are up.

“We think it’s due to a variety of factors. Some of it may be related to how we live today. We live in a cleaner environment. It may be changing how your immune system works, particularly early in childhood,” says Dr. Deborah Gentile, an allergist at Allegheny General Hospital.

A study in the Journal of Allergy and Clinical Immunology looked at annual government surveys of hospitals and other studies on food allergies and ER visits. The numbers appear to be swelling. In the 1990s there were about 200,000 trips to the ER. After the turn of the century, there were just over a million.

“We do pick up some new diagnoses that are referred to us from the emergency room,” Gentile says.

It seems more children especially are headed to the ER for these severe reactions to food. The increase is in line with the number of children being diagnosed with food allergies: three million as of 2007 – an 18 percent increase over a decade. The good news is many children outgrow their allergies.

“We think a lot of it is just due to their immature immune system. We know that even in a healthy person, the immune system is still developing those first several years. And certainly that’s an age where you’re going to be prone to have problems,” Dr. Gentile explains.

The most common triggers are milk, eggs, shellfish, soy, wheat and nuts.

The symptoms range from mild — like mouth tingling — to a more severe whole body reaction — like trouble breathing, bad swelling and a sudden drop in blood pressure. The more severe symptoms can be life-threatening and these require emergency treatment.