Fish allergy develops late in life

Food allergies usually appear in infancy and childhood yet while 2–3% of adults in the US have seafood allergies, less than 1% of children do. The most common triggers are shellfish.

Scientists have identified several allergens in seafood, most importantly a protein called tropomyosin. But it’s not entirely known why some people have allergic reactions to these substances and others don’t. In some cases, a genetic predisposition to developing allergies is to blame.

Dr David Hong, an allergist and immunologist at Brigham and Women’s Hospital, says that seafood allergies are the most common to develop later in life and that if you suspect you have a shellfish allergy, the first step is to make sure it’s a true food allergy rather than a food intolerance. A doctor can usually make the diagnosis using a skin or blood test.

A fish allergy reaction occurs quickly, typically within 15 to 20 minutes of ingesting the food. Symptoms include nausea, vomiting, diarrhoea, itching, hives, and difficulty breathing. In some cases, life-threatening anaphylactic shock can develop, involving extreme respiratory distress and circulation failure.

Dr Hong recommends that anyone with a fish (or indeed any food) allergy, particularly people with asthma, carry an epinephrine auto-injector, such as an EpiPen, which can stop an anaphylactic reaction.

Courtesy of the Boston Globe

First published in April 2010

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