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Overview

Allergic symptoms of a corn allergy develop when a person’s immune system becomes sensitized and overreacts after eating corn or foods containing corn-based ingredients, or after being exposed to corn pollen. Corn and corn-derived products are used in many processed foods, as well as in many other everyday items.

A corn allergy can be difficult to diagnose using standard skin or blood tests because it is difficult to differentiate from allergies to grass pollens and to other seeds and grain. A food elimination diet, in which specific items are removed from a person’s diet for a period of time to see if symptoms improve, is one way to determine whether a corn allergy is present.

Corn Allergy Symptoms

  • Hives or a skin rash
  • Nausea, stomach cramps, indigestion, vomiting or diarrhea
  • Stuffy or runny nose
  • Sneezing
  • Headaches
  • Asthma
  • Anaphylaxis (less common), a potentially life-threatening reaction that impairs breathing and can send the body into shock

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Corn Allergy Triggers

  • Corn

Most corn-derived products, like cornstarch and high-fructose corn syrup, do not contain corn protein. If you have a corn allergy, you do not need to avoid these products.

Corn Allergy Management and Treatment

  • Avoid corn and corn-derived products.
  • Administer epinephrine (adrenaline) to counter a severe reaction.

Symptoms

Symptoms of an allergy to corn include:

  • Hives or a skin rash
  • Nausea, stomach cramps, indigestion, vomiting or diarrhea
  • Stuffy or runny nose
  • Sneezing
  • Headaches
  • Asthma
  • Anaphylaxis (less common), a potentially life-threatening reaction that impairs breathing and can send the body into shock

Physical reactions to corn and corn products may range from mild to severe. A life-threatening allergic reaction is anaphylaxis, in which airways swell, breathing is impaired and blood pressure is lowered. It can come on very quickly; if it isn’t treated with epinephrine(adrenaline) as soon as symptoms are noticed, it can be fatal. Published case reports have reported life-threatening anaphylactic reactions to corn-based products such as a dextrose intravenous solution and cornstarch used to powder surgical gloves.

Diagnosis

Diagnosing a corn allergy can be complicated. Symptoms can vary from person to person, and a single individual may not always experience the same symptoms during every reaction. If you suspect you are allergic to corn, make an appointment to see an allergist who specializes in food allergies. Start a food diary before the appointment, and keep track of any reactions. If you have a reaction, you should note: What (and how much) you ate When the symptoms started What you did to alleviate the symptoms How long it took before the symptoms were relieved Your allergist will ask you about your history of allergy symptoms. You’ll also be asked about your overall health and your family medical history, including any relatives with allergies. Because a corn allergy can be difficult to diagnose through skin tests or blood tests, your allergist may put you on a food elimination diet, in which you avoid the suspected food allergen for a specific period of time (normally two to four weeks). If your symptoms improve when the item is removed from your diet, it’s likely that you are allergic to it. If the food elimination diet produces inconclusive results, your allergist may recommend an oral food challenge. During this test, you will be fed tiny amounts of corn or corn products in increasing doses over a period of time in an allergist’s office or a food challenge center. Emergency medication and emergency equipment will be on hand during this procedure in case you have a severe reaction.

Management and Treatment

Once a corn allergy has been diagnosed, the best treatment is avoidance of corn or corn-derived products which are known to contain corn protein, such as corn flour.

Note that maize is the same as corn.

Corn is not one of the top eight food allergens for which special label information is required by the Food Allergen Labeling and Consumer Protection Act of 2004, so learning the names of products and ingredients that can be derived from corn is especially important for someone with this allergy. These include baking powder, caramel, cellulose, citric acid, dextrin, dextrose, inositol, malt, maltodextrin, monosodium glutamate (MSG), semolina, sodium erythorbate, sorbitol, starch, vanilla extract, xanthan gum and xylitol. Check with a product’s manufacturer if you have any questions about an ingredient’s origin.

Corn and corn-derived products are found in a wide variety of packaged foods, including:

  • Cereals
  • Candies
  • Jams
  • Syrups
  • Sauces
  • Snack foods
  • Canned fruits
  • Prepared meats, such as hot dogs and deli meats
  • Beverages

As with any food allergy, you will have to make some changes in what and how you eat. Your allergist can direct you to helpful resources, such as food allergy cookbooks and patient support groups. A registered dietitian can help you devise a food plan.
Corn-based ingredients can also be found in nonfood items as diverse as shampoo, toothpaste, IV solutions, vitamins, cosmetics, crayons, dishwashing liquid, clothing, paint, plastics and pet food. Cornstarch, for example, can serve as both an adhesive and a coating in paper products, and is even used in disposable diapers.