How can smelling fish cause an allergic reaction? Here's everything you should know about allergies

An 11-year-old boy died this week after he experienced a reaction to the smell of fish cooking on the stove while visiting his grandmother’s home for the holidays.

Cameron Jean-Pierre’s mother, Jody Pottingr, told ABC News that he had been diagnosed with a fish allergy and asthma, and that he had previously used a breathing treatment when he’d become short of breath from inhaling the fish aroma.

The molecules that make food smell a certain way are typically not allergens, so most of the time, sniffing food will not cause an allergic reaction. However, if you’re close enough to sniff the food, you’re likely close enough to inhale any allergens when they are present.

Here are some important facts to know about food allergies.

In an allergic reaction, the body’s defense system incorrectly detects danger.

A food allergy occurs when the body’s immune system overreacts to a specific food on a regular basis. The most common foods people are allergic to include cow’s milk, peanuts, tree nuts, soy, fish, shellfish and wheat.

At least two children in every classroom will have a food allergy, and almost a third of those children will also suffer from asthma, eczema or another allergy. Food allergies in children under 18 have been increasing over time, jumping 18 percent between 1997 and 2007, according to the Centers for Disease Control and Prevention's latest statistics.

Allergens have different ways of getting into the body, including by inhaling them.

Food allergens are proteins within the food that cause the body to produce a harmful response. Though they are not actually dangerous, the body perceives them that way. Food allergens often enter the body’s bloodstream by eating or drinking them. But in some cases, such as Cameron’s, they can enter by inhaling them as well — they are transported in the steam coming from a simmering pot.

You can’t have an allergic reaction to the smell of food if the food’s odor is produced by something other than these proteins. That’s why people with peanut allergies who smell peanut butter most likely won’t have an allergic reaction. However, the smell may alert them that peanuts are close by and they should be careful.

Allergic reactions are different for everyone.

Symptoms can range from mild to severe and include a tingling tongue, itchy skin or hives and abdominal pain.

When food allergies cause the airways to swell, making it difficult to breathe, they are experiencing anaphylaxis, which is a life-threatening reaction that requires immediate hospitalization. Untreated anaphylaxis can lead to coma or death. Children with food allergies and pre-existing asthma are at higher risk for an anaphylactic reaction.

Children can 'outgrow' food allergies.

Food allergy symptoms may decrease with time and eventually become insignificant, but many children have lifelong allergies. Some people may even develop food allergies in adulthood. The likelihood of outgrowing an allergy depends on the allergen. It’s more common to outgrow egg and milk allergies and less common to outgrow peanut allergies.

Mild food allergies can still cause severe reactions.

Food allergies are unpredictable, and it’s impossible to know if the next reaction will be mild, moderate or severe. If you have a food allergy, it’s important to have a plan in place for every type of reaction. Speak with your doctor to ensure you have a plan in place.

Allergic reactions can be treated, but cures for food allergies are still being explored.

It is important for adults and children to avoid foods that may trigger their allergies. If an allergic reaction does occur, treatment depends on the type and severity of symptoms. People who have a history, or are at risk for severe reactions may carry an injectable epinephrine device, which shuts down the body’s allergic response.

Curative treatments are promising and still undergoing clinical trials. Oral immunotherapy, for example, involves introducing small amounts of an allergen under controlled conditions to suppress the allergic response over time and allow the patient to safely incorporate the allergen into their diet.

Dr. Naomi Kaplan is a resident physician in physical medicine and rehabilitation and a member of the ABC News Medical Unit.