Food allergies are very common, affecting an estimated 5 percent of adults and 8 percent of children.

The eight most common food allergies are:

  • cow’s milk
  • eggs
  • tree nuts
  • peanuts
  • shellfish
  • wheat
  • soy
  • fish

While mayonnaise doesn’t appear in that list, the most common food allergen found in mayonnaise is egg.

According to the American College of Allergy, Asthma, and Immunology (ACAAI), egg allergies mostly affect children. In fact, about two percent of children are allergic to eggs, but 70 percent of them outgrow it by the time they’re 16 years old.

The most common allergen in mayonnaise is egg. In rare cases, other ingredients in mayonnaise may cause an allergic reaction.

It’s also possible to have a food intolerance with mayonnaise, rather than an allergy. While allergies cause your immune system to respond, food intolerances cause your digestive system to react.

If you have a food intolerance, you can often eat a small amount of the food in question. But when you have a food allergy, even tiny amounts of the food may cause a life-threatening reaction.

Food allergies occur when your body overreacts to a substance in the food and identifies it as a foreign invader. To fight the allergen, your body releases various substances that cause the allergic reaction.

If your symptoms are severe enough, you can go into anaphylactic shock. This causes your blood pressure to drop and your airways to narrow, making it hard to breathe. This can be life-threatening.

Ingredients vary based on the manufacturer of the mayonnaise or whether it’s homemade.

Homemade recipes often call for:

  • egg yolk
  • fresh lemon juice
  • white wine vinegar
  • Dijon mustard
  • salt
  • a neutral-flavored oil (canola, avocado, safflower)

Commercial varieties can have:

  • soybean oil
  • eggs and egg yolk
  • distilled vinegar
  • water
  • salt
  • sugar
  • lemon juice concentrate
  • dried vegetables and herbs, like dried garlic or onions
  • preservatives, like calcium disodium EDTA
  • natural flavorings

Other possible allergens in mayonnaise

Although the most common allergen in mayonnaise in egg, it’s possible in rare cases to be allergic to some of the other ingredients, including:

  • soybean oil, due to a soy allergy, especially if it’s expeller pressed or cold pressed
  • lemon juice, due to a citrus allergy
  • vinegar, due to a sulfite allergy
  • mustard, due to a mustard allergy

In the United States, the Food and Drug Administration (FDA) requires foods containing eggs to be called out on the label.

But you won’t always recognize something has eggs in it by the label, since other terms for “egg” may be used. Some key words to look for include:

  • albumin (egg white)
  • lysozyme (an enzyme found in egg whites)
  • lecithin (a fat found in egg yolks)
  • livetin (a protein found in egg yolks)
  • vitellin (a protein found in egg yolks)
  • globulin (a protein found in egg whites)
  • words starting with ova or ovo (for example, ovalbumin, which is another protein found in egg whites)

It’s important to always read food labels and ask questions when you’re dining out. Eggs are put into a lot of products, and some of them might surprise you. For example, eggs can be found in:

  • egg substitute products
  • marshmallows
  • pastas
  • ice cream
  • pretzels, bagels, and pies
  • flu vaccine

Most food allergies — whether they stem from eggs, nuts, milk, or something else — produce the same symptoms. Egg allergy symptoms may include:

  • hives
  • rash
  • stomach cramps
  • vomiting
  • diarrhea
  • chest pain
  • difficulty breathing as your airways swell up
  • weakness and confusion

If you suspect you may be allergic to mayonnaise, it’s important to speak with your doctor and start tracking what you eat.

Keep a food journal

The first step to diagnosing a food allergy is keeping a detailed food diary. This can give you and your doctor an indication if you’re allergic to a food. Write down:

  • everything you consume
  • how much
  • when you ate it
  • how you felt after eating it

Get a skin-prick test

Another diagnostic tool is a skin-prick test. This test can be performed by an allergist, which is a doctor who specializes in diagnosing and treating allergies.

To perform the test, an allergist will use a small, sterile needle that contains some of the allergen and prick your skin.

If you develop a reaction to the substance (usually a red, itchy welt where the skin was pricked), there’s a greater than 95 percent chance that you have an allergy if you’ve had symptoms after eating the food in the past.

Get a blood test

Blood tests can also be used, but they’re slightly less accurate than skin-prick tests. A blood test will show if you produce antibodies to common foods that cause allergies.

Try an oral food challenge

Another test is called an oral food challenge. Your doctor will feed you gradually increasing amounts of the suspected allergen and watch for a reaction.

This can produce a life-threatening reaction, so it should only be done under medical supervision in a setting that has emergency medication and equipment.

Try an elimination diet

Lastly, your doctor may advise you to try an elimination diet. This diet has you eliminate all foods commonly associated with allergies and then allows you to reintroduce them, one at a time, and record any symptoms.

The best way to prevent an allergic response is to steer clear of the thing that causes it — in this case, mayonnaise. Read all food labels, ask questions at restaurants, and make substitutions when you can.

Mayonnaise lends a creamy texture and taste to sandwiches, dips, and dressings. Look for products that can replace some of the creaminess. Suggestions include:

  • cottage cheese, especially puréed
  • cream cheese
  • Greek yogurt
  • butter
  • mashed avocado
  • pesto
  • hummus

The most common allergen found in mayonnaise is egg. If you think you might be allergic to mayonnaise, see your doctor or an allergist for an evaluation and possible testing. Remember to always read food labels and ask questions when ordering in restaurants.

If your tests come back positive for an allergy, you’ll receive a prescription from your doctor for a pen-like instrument that you can use to inject yourself with a drug called epinephrine (commonly called an EpiPen). Epinephrine is a drug that can save your life if you have a severe allergic reaction.