Everything you need to know about a sesame allergy

The likelihood of outgrowing a sesame allergy is low, and the risk of accidental exposure is high. Here's everything you need to know.

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Dipping a plain cracker or carrot in hummus is a great way to boost its nutritional content and flavour, but if your child has a sesame allergy, even a tiny taste of the spread can cause a serious reaction. Sesame is a major cause of life-threatening allergic reactions in the Middle East, where it’s widely consumed as tahini (a paste used in hummus), and these reactions are becoming more common in Canada.

“We’re seeing more sesame allergies,” says Harold Kim, an allergist in Kitchener, Ont., and president of the Canadian Society of Allergy and Clinical Immunology. “The possible reason why is because we’re eating more of it in childhood—not necessarily sesame seeds but sesame products, such as tahini in hummus. Sesame is now considered a priority allergen [in Canada] because it has become relatively common.”

What is a sesame allergy, and how common is it?

A sesame allergy occurs when your immune system mistakenly identifies a protein in the seed as dangerous, releasing chemicals that cause a reaction. About one in 1,000 children in Canada has a sesame allergy, making it less common than other food allergens, such as peanut and egg, which affect up to three percent of kids.

How to know if your kid has a food allergy or food intoleranceAs few as two sesame seeds can trigger a reaction, and many children react the first time they eat sesame. Babies can even have a reaction through breastmilk, though it is unlikely to be severe and may only involve a mild rash. To become allergic to sesame, kids have to first be exposed to the seed in some way. This may happen by eating it, being exposed through broken skin (such as eczema) or coming in contact with it in another way not yet understood by experts.

What are the symptoms of a sesame allergy?

The symptoms of a sesame allergy typically set in within minutes of consuming the seed and can range in severity. Many children experience skin symptoms, such as hives, rashes, itchiness and swelling. Respiratory symptoms, including shortness of breath, throat tightness and nasal congestion, are also common. Some kids have a tummy ache, vomiting or diarrhea or may become weak and groggy.

Anaphylaxis is a severe allergic reaction and a life-threatening medical emergency. It typically comes on quickly and involves two or more body systems, such as the skin and respiratory system, but that’s not always the case. “If a child gets really groggy immediately after eating the food, that on its own might be a sign of a severe allergic reaction,” says Kim.

The most serious symptoms of anaphylaxis are difficulty breathing and a drop in blood pressure, which can cause children to turn pale or blue, become light-headed, dizzy, irritable or drowsy and even pass out. Anaphylactic shock occurs when a major organ is affected by extremely low blood pressure (if the blood flow to the brain is too weak, a child may pass out). 

Research shows that about three percent of food-induced cases of anaphylaxis in Canadian children are caused by sesame, compared to 43 percent of cases in Israeli children, where hummus and other products made of sesame are consumed frequently.

If your child is having a severe reaction, you should call 911 immediately.

How do you treat a sesame allergy?

If your child is having a mild reaction to sesame for the first time, such as hives, Kim says that it’s safe to wait and watch. You should still see your doctor as soon as possible for an assessment, even if the reaction doesn’t progress. However, if the reaction involves anything more than mild symptoms, you should call 911.

At the hospital, your child may be treated with epinephrine, a life-saving drug that stops the reaction. Your child may also be given antihistamines and steroids and be closely monitored until medical staff are sure that it’s safe to go home. Once your child is diagnosed with a sesame allergy, you should always have an epinephrine auto-injector (called by the brand name EpiPen in Canada) on hand and make sure that everyone who is caring for your child knows how to use it. At the first sign of a serious reaction, you should call 911 and give the child an EpiPen.

If your child has mild symptoms that are not progressing but are bothersome, such as itchy, watery eyes and hives, you can give them a non-drowsy antihistamine. It’s important to wait at least 30 minutes to ensure that the reaction isn’t escalating, as an antihistamine can mask the progression of symptoms.

Is there a cure for a sesame allergy?

There is no cure for a sesame allergy but new treatments may be forthcoming in the future. Oral immunotherapy, in which a child is given gradually increasing doses of the allergen to build up tolerance under the supervision of an allergist, has shown promise for other foods, such as peanut, but it has not yet been systematically studied on sesame. However, Kim says we can expect to see this treatment in the future. “At this point right now, the level of evidence is not high enough to say that it works, but it’s possible and I would say likely,” he says.

How do you diagnose a sesame allergy?

If you suspect that your child has a sesame allergy, they should be seen by an allergist, who will likely do a skin prick test, a blood test or both. The skin prick test involves exposing skin to the allergen and seeing how big of a weal (an area of irritated skin) develops around the site. The bigger the weal, the more likely it is that your child is allergic.

An oral food challenge, in which small amounts of the suspected allergen are consumed under the supervision of a doctor, may also be done. Oral food challenges are typically done if the child’s reaction and tests are not conclusive or if a sesame allergy is suspected but the child has not been exposed. An oral food challenge may also be done in the years following the initial diagnosis to see if a child has developed a tolerance to sesame.

What foods should your child avoid if they have a sesame allergy?

Sesame seeds, which can be white or black, can be found in all kinds of foods, so it’s important to be vigilant in reading labels and asking questions at restaurants. Like other common allergens, sesame must be listed as an ingredient in packaged foods. However, labels indicating that products may contain sesame are voluntary. In the United States, sesame is not required to be labelled as an allergen on packaged foods, but the U.S. Food & Drug Administration is exploring the possibility of regulatory action that requires it to be listed.

Sesame seeds are frequently found in baked goods, cereals, snack foods and vegetarian products. Sesame oil is a common ingredient in many dishes, especially Asian cuisine, and tahini can be found in spreads, sauces and salad dressings. Whole roasted sesame seeds are also becoming more common in grocery store snack aisles and as salad toppers. “Sesame can also be used as a protein in unexpected foods, such as vegetarian burgers,” says Kim. “You have to be really cautious.”

Indeed, a Canadian study published in 2017 found that accidental exposure to sesame seeds occurs at an annual rate of 16 percent, with older children more frequently affected, possibly because they’re more likely to take risks and less likely to be supervised by their parents.

Kids can also come in contact with non-food products that contain sesame, such as bandages, sunscreens and pet food, so be vigilant and read labels. If you’re uncertain about ingredients, you can call the companies to ask.

Can a sesame allergy be outgrown?

Studies have found that between 20 and 30 percent of children outgrow sesame allergies. For example, a US study found that 27 percent of children achieve tolerance by a mean age of about five and a half. Children are more likely to outgrow sesame allergies if they develop the allergy early in life, have mild to moderate reactions, only experience skin symptoms and aren’t allergic to other foods.

Read more:
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