“Headed to ER with our son covered in hives after eating Chinese food.”
This all-too-common text popped up on my phone in mid-May, written by a dear friend and stellar local pediatrician. Her 10-year-old son had hives and eye-swelling, and they were wisely headed to the hospital. He had a very diverse diet prior to this meal without evidence of food allergies. His sudden symptoms appeared 30-45 minutes after eating take-out Chinese at his grandparents’ home and just after playing in the grass.
So often parents walk into doctors’ offices and emergency rooms, describing similar scary stories. As physicians, our first job is to make the reaction stop. Once the patient is stabilized, we face the same confusing question that all parents ask: “Was this a food allergy, an environmental allergy or something else?” Weeks later, and in the case of my friend’s kid, I still can’t say for sure.
What we don’t know about food allergies
True food allergies have been on the rise over the past couple decades. New “fad” diagnoses can be controversial due to something called detection bias. Detection bias happens when a disease may seem more common if doctors and researchers are looking for it more aggressively. And yet, even controlling for detection bias, the Center for Disease Control and Prevention (CDC) estimates the rate of food allergies has risen 18 percent since the late 90s. Food allergies affect four percent of adults and as high as eight percent of children in the US, which amounts to over six million kids.
It has been difficult to measure how common true food allergies are in the population as opposed to environmental allergies. The gold standard test for food allergy is the oral food challenge, which requires actually giving the food to a patient to eat and monitoring for a reaction. Physicians are hesitant to trigger symptoms just to diagnose an allergy, especially in children. Doctors are often forced to rely on the family’s self-reporting based on medical history or imperfect tests. Testing can also be done by skin prick or with blood samples, but these assays are incorrectly positive in up to 50 percent of cases.
Which foods to worry about
Allergists in the US think of the Big Eight food culprits in descending order of prevalence as milk, eggs, peanuts, tree nuts, shellfish, fish, wheat and soy. These foods account for as much as 90 percent of food allergy. It’s important to note that peanuts are legumes rather than tree nuts. Thus, when we discuss nut allergy, we’re referring to tree nut allergy, not peanut. There are similar proteins found in tree nuts and peanuts, however, so there is still an increased risk of cross-reactivity between peanut and tree nut proteins. [post_widget id=”6435″]
Shellfish and finned fish are considered separate allergens with different shared protein families. Shellfish include crustaceans such as shrimp, lobster and crab, and mollusks such as clams, oysters and scallops. There are children who can tolerate shellfish or fish but not both. It is important to discuss with your allergists if your child needs to avoid all seafood.
Soybeans fall into the legume family along with peanuts, lentils and peas. There is less cross-reactivity within the legume family, so kids with soy allergies often are not allergic to other legumes. Soy is common in vegetarian cuisine due to its protein content and can be present across Asian cuisines. Edamame, tofu, soy sauce and tempeh are all examples of soy-based foods.
In countries other than the US, different food allergens are prevalent due to different cultural diets. For example, mustard is a common allergen in Canada.
Signs and symptoms of allergic reactions to food
“A little coughing during the meal. Thought he’d swallowed wrong. Seemed fine and played catch later. Then, hives started maybe 30 minutes later. Maybe a little longer. He had Chinese food for dinner: fried rice with shrimp, pot stickers and a spring roll.”
True food reactions are defined as an “adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food.” Allergic reactions usually appear seconds to minutes after ingesting the food protein, but can be delayed up to a couple of hours. As seen in this case, hives and swelling are very common reactions. Indeed, skin symptoms like flushing or a rash are the most common, though they’re not always visible. Other symptoms include gastrointestinal symptoms like diarrhea, stomach pain and vomiting; head symptoms like nasal itching and sneezing; oral symptoms such as itching, tingling and swelling; and respiratory symptoms like coughing. Difficulty breathing and shock are extremely rare but most concerning.
Other diseases such as celiac disease, intolerance or FPIES (food protein-induced enterocolitis syndrome) may be mediated by our immune system but are not considered allergies, as they are delayed and inconsistent. Reactions that are not allergic are less likely to be dangerous as well.
The key feature of a true food allergy is that the body will react each time it encounters a food allergy trigger. Reactions tend to be worse with each subsequent exposure. Any food that you can tolerate after a reaction is likely safe but should be discussed with your physician.
How do I know if my child is having an allergic reaction?
Some symptoms that are common with food allergies can also be common characteristics of children simply eating. Children often have flushing while eating and, as parents know all too well, spitting up and stomach aches are quite common in young children. Infants with eczema have symptoms throughout the day, so given the frequency of feedings, it can be difficult to decipher if eczema is flaring due to eating or other factors. Symptoms that fade quickly without treatment are less likely to be allergic ones. Symptoms that happen with many different foods and inconsistently suggest non-allergic reactions as well.
If there is any doubt about your child’s symptoms, consult your pediatrician or, if the reaction is more severe, go straight to the emergency room. If you feel that the reaction is getting dangerous, call 911 for an ambulance so that care starts immediately and continues en route to the hospital.
All children with known food allergies should have an allergy action plan. In conjunction with your physician’s advice and the action plan, treatments such as Benadryl and Epinephrine may be indicated. Once your child is treated and stable in the ER, you may be discharged after three or four hours, or the next morning. Follow up with your pediatrician, and we highly recommend seeing an allergist as well.
There’s still a lot we don’t know about food allergies. Differentiating between symptoms caused by the environment and by foods can be nebulous, so it’s important to watch your child’s reactions to specific foods over multiple encounters. With your family’s allergist, develop an allergy action plan, work on a safe home to minimize accidental food contact or ingestion and be diligent with reading the labels of your food products. When eating away from home, be adamant about food preparation, asking a manager or chef about their practices. Internet resources such as Allergy Eats can help you find safe restaurants. Our pediatric food allergy patients are quite precocious. Even at a young age, talking to them about their allergies can effectively teach them the importance of communicating their allergies to teachers, caregivers, other parents and peers.
Within this blog post, we have discussed the Big Eight food allergens: milk, egg, soy, wheat, peanut, tree nuts, fish and shellfish. We’ve also described some of the characteristics suggesting your child is having a food reaction, such as immediate and worsening symptoms that occur consistently and increasingly with a certain food. Remember that if there is any doubt of your child’s well being, get your child to the ER as safely and as quickly as possible. In the next post, we’ll discuss testing, prognosis and the possibility of preventing food allergies.
Dr. Steve Handoyo is a Clinical Associate of Pediatric Allergy and Immunology at the University of Chicago. For more information or to schedule an appointment, please visit his University of Chicago page or call 773.702.6169.