A corn allergy is an increased sensitivity to corn when ingested. Consuming a food with corn proteins can cause allergy symptoms such as coughing, sneezing and swelling of the tongue, face and throat. A severe corn allergy reaction can even lead to death. This type of food allergy is rare, though it can be very difficult to manage because of the large number of foods that include corn proteins (e.g., corn syrup, corn meal, cornstarch).

Those individuals who have severe allergic reactions to corn need to be especially cautious because a food allergy can trigger potentially life–threatening anaphylactic shock. This condition is characterized by difficulty breathing and a dangerous drop in blood pressure.

Corn allergies are triggered by eating one of the many foods that contain corn or corn proteins. However, the condition is triggered only by corn proteins, not corn oils.

A physician can help diagnose a patient with a corn allergy by using several types of tests and treatments and reviewing the patient’s medical history. An evaluation of a patient’s diet can also help pinpoint corn as a problem food. Because a corn allergy is so rare and because so many foods contain corn proteins, the diagnosis of a corn allergy often takes longer than for other food allergies.

The only method for treating a corn allergy is the complete removal of any foods containing corn or corn proteins from the diet. The list of problem foods associated with this condition is enormous and corn allergic individuals must work very hard to successfully avoid foods that could contain corn allergens. Individuals with this condition should work closely with their physician to better manage their diet.

It is important to note that not all reactions to food are allergic reactions. Corn intolerance is a reaction to eating corn that does not involve the immune system. Reactions associated with food intolerance are usually less severe than the reactions involved with food allergies.

A corn allergy is a rare sensitivity to the protein found in corn and many types of corn products. When people with this type of food allergy ingest corn proteins, it triggers an allergic reaction. This can lead to life-threatening anaphylactic shock or an asthma attack in individuals with asthma.

An allergic reaction to corn occurs when the immune system encounters a corn protein and mistakes it for a dangerous substance. To combat the perceived threat, the immune system triggers the release of antibodies that further trigger the release of inflammatory chemicals known as histamines. This chain of events is known as the allergic cascade.

Histamines are responsible for causing common allergy symptoms such as sneezing, swelling and coughing. These symptoms usually appear within minutes, but it is possible for a late-phase allergic reaction to occur several hours later.

People with corn allergies can experience anaphylactic shock, which is a potentially deadly condition involving difficulty breathing and a dangerous drop in blood pressure. Anyone experiencing an anaphylactic reaction should seek immediate medical attention.

While it is uncommon to have an allergic reaction to corn, the pervasiveness of corn and corn products in society can make this a difficult allergy to manage. Corn proteins are used in a wide variety of foods, either as corn itself or as a corn derivative (such as dextrin). Sensitive individuals can consume even a small quantity of corn protein and experience allergy symptoms. Fortunately, removing corn from the diet does not cause any nutrient deficiencies.

Sensitivity to corn varies from individual to individual. Some individuals are able to tolerate foods that have a very low quantity of corn protein. Others find that boiling corn until it is soft allows them to eat the food without a reaction. Why some individuals with corn allergies can tolerate cooked corn and others cannot is not entirely understood. However, it is known that cooking foods can alter certain food proteins. Some people may not be sensitive to the altered proteins.

Susceptibility to corn allergies is believed to be genetic. Individuals with a personal or family history of any type of allergy (e.g., allergic rhinitis or eczema) are more likely to have a corn allergy. Individuals who have a corn allergy should work with their physicians to better manage the condition.

It is often difficult for an individual to identify a corn allergy on their own because of the large number of foods that contain corn and corn protein. Physicians, too, may not immediately pinpoint corn as the problem food because the condition is so rare.

Some people who experience symptoms after eating corn are suffering from food intolerance and not a food allergy. Food intolerance involves the inability of the body to digest a substance, leading to symptoms of discomfort (e.g., stomach cramping) but usually posing little danger. Generally the symptoms of corn intolerance are milder than those associated with a corn allergy. With a corn allergy, even a very small portion of a food allergen can cause an allergic reaction.

Individuals with a corn allergy will experience an allergic reaction after consuming corn or food products containing corn protein. While some individuals can tolerate some types of corn-containing food, people with a corn allergy should be wary of all foods containing corn proteins. Only corn proteins are problematic. Proteins are removed from corn oils, so corn oils do not generally cause a problem for people with corn allergies.

The list of foods containing corn is enormous and it is realistic to suggest that most foods found in a typical pantry contain corn proteins. Here is a list of many of the foods and products that often contain corn proteins (Note: This is not a complete list):

• Baby formulas
• Dairy products (e.g., cheese, sour cream)
• Condiments (e.g., mayonnaise, mustard)
• Meat products (e.g., hot dogs, sausage)
• Fresh orange juice (not frozen or bottled)
• Packaged cereals
• Baked goods
• Iodized salt
• Pickles
• Some alcoholic beverages (e.g., bourbon, blended scotch, some beers)
• Salad dressings
• Spaghetti sauces
• Teas
• Tomato products
• Peanut butter
• Candies and breath spray
• Wax-coated fruits and vegetables
• Frozen fruits (e.g., cranberries, blueberries)
• Applesauce and other canned fruit
• Frozen vegetables
• Margarine
• Cream
• Liquid and pill form of some medications
• Chinese food
• Potato chips
• Sweetened soft drinks
• Envelope and stamp adhesive

Because of the large number of products that contain corn proteins, it is important that people with corn allergies learn the names of the many types of corn derivatives. These derivatives will be listed on the ingredients label of food packages, even if corn itself is not. 

Common corn-derived ingredients include (Note: This is not a complete list):

• Dextrose (also known as corn sugar)
• Dextrin
• Dextrates
• Maltodextrin
• Caramel
• Starch
• Malt syrup
• Food starch
• Hydrolyzed protein
• Vegetable protein
• Vegetable gum
• Vegetable starch
• Acetic acid
• Baking powder
• Fructose
• Sorbitol

The first step a physician is likely to take in the diagnosis of a food allergy is to create a detailed medical history and dietary history of the patient. However, it is often difficult to obtain a quick diagnosis for this type of condition because the symptoms of a corn allergy mimic those of other allergies (e.g., pollen, mold).

By gathering basic information, a physician can get a better idea of where to proceed with further evaluations. This may include attempts to identify the specific allergen to which the patient is sensitive. Such procedures are not definitive, but can provide information that is relevant to the patient’s condition and useful in designing treatment plans. These measures may include:

• Skin test. This test involves pricking the patient’s skin with food extracts. The skin will react with redness and swelling for those extracts capable of eliciting an allergic reaction when consumed. This type of test provides results that are accurate; however, the results will vary depending on the food being tested.
  

  

   
• RAST (radioallergosorbent test). This type of blood test allows a laboratory to directly test a blood sample for antibodies that correspond to specific foods. While less sensitive than a skin test, it can be used on individuals who have reactions too severe for a skin test.
  
  
• Oral food challenge. Also called the double-blind food challenge, this is considered the most effective way of determining the cause of a food allergy because it supplies the most convincing results. Different foods are placed within capsules to hide their identity. Neither the patient nor the physician knows which capsule contains the suspected allergen. The patient consumes the capsules and the physician looks for signs of an allergic reaction. This type of test is time-consuming and difficult. It is often reserved to confirm suspicions that a patient's symptoms are not caused by a food allergy. This type of test should only be performed in the presence of a physician who can treat anaphylaxis.
  
  
• Elimination diet. This process involves removing suspect foods from a patient’s diet to see if the allergic reactions persist. Foods are removed on a trial-and-error basis for a period of time. The results of the diet make it easier to confirm, rule out or permanently remove a problem food.

The key to successfully preventing allergic reactions to corn is eliminating corn and foods with corn proteins from the diet. Considering the large number of foods that contain corn proteins, this can be a massive undertaking. However, successfully modifying the diet to exclude corn products will result in the complete elimination of corn allergy symptoms. Corn oils, which do not contain corn proteins, are generally safe.

Here on some specific tips that may help manage a corn-free diet:

• Keep a diary of foods and symptoms. Making notes about everything that is eaten and any symptoms (even minor ones) can help identify any hidden products that might contain corn and be responsible for triggering an allergy. Food diaries are only effective when the patient records every food that is eaten. For this reason, patients should always record their foods immediately after they are eaten.
  
  
• Find a good place to shop. Many areas have grocery stores that sell organic and specialized foods. These can be a valuable resource to a person with a corn allergy, as they often offer many types of alternative foods that may omit ingredients such as corn. Inquire about corn-free foods at the stores in your area.
  
  
• Avoid fast food. Most fast food will have corn of some type as an ingredient, from corn starch (e.g., breads, hot dogs) to corn syrup (e.g., soda, desserts, condiments). If it is a must, a plain hamburger or unbreaded chicken meat without a bun, with water or pure fruit juice are the best choices.
  
  
• Inform all physicians. Make sure any physician that is writing a prescription for you knows of your condition. Some types of medication contain corn proteins.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following corn allergy-related questions:

1. What methods will you use to determine if I am allergic to corn?
   
   
2. What treatment methods are available to me?
   
   
3. Is it safe for me to consume small amounts of corn?
   
   
4. What should I do if I consume a corn product accidentally?
   
   
5. Are my children more likely to develop a corn allergy because I am allergic?
   
   
6. Will my child outgrow his or her allergy to corn?
   
   
7. What terms should I look for on product labels?
   
   
8. What products should I avoid?
   
   
9. How do I know if my baby’s formula contains corn products?
   
   
10. Will corn oil trigger a reaction?