Scott H Sicherer, MD, FAAAAI
Robert A Wood, MD
Elizabeth TePas, MD, MS
FOOD ALLERGY OVERVIEW — People with food allergies can have serious or even life-threatening reactions after consuming certain foods. The most important strategy in the management of food allergies is to avoid eating these foods.
However, it is not always easy to know if packaged foods or meals at restaurants contain allergens, so it is also important to know how to treat an allergic reaction.
This topic will discuss tips for living with food allergies, non-food sources of food allergens, and the importance of having a food allergy emergency action plan. The symptoms and diagnosis of food allergies are discussed in a separate topic. (See “Patient information: Food allergy symptoms and diagnosis”.)
Some children with food allergies have difficulty getting the proper amount and type of foods in their diet. This issue is discussed in detail in a separate article. (See “Nutritional issues in food allergy”.)
GENERAL FOOD ALLERGY CONSIDERATIONS — People with food allergies are typically told to completely avoid the offending food. However, it is often difficult to do this in real life. As a result, anyone with food allergies must be prepared to treat an unexpected allergic reaction at any time and in any setting.
How careful do I need to be? — In general, people with food allergies must strictly avoid eating or drinking anything that contains even a minuscule amount of a food allergen. It is not possible to know what amount of the allergen will trigger an allergic reaction. (See “Food allergen avoidance”.)
Eating, touching, and inhaling allergens — Most people with food allergies react after eating a food. Other types of exposure, such as touching or inhaling the food, may lead to localized reactions (eg, hives) in children. However, this type of exposure is unlikely to cause severe reactions in most people with food allergies.
Smelling foods is also unlikely to cause a severe reaction. As an example, the smell of peanut butter is related to volatile organic compounds (VOCs), substances that evaporate easily. The smell of peanut butter is not related to particles of peanut butter in the air, so it is not likely to trigger an allergic reaction.
However, inhaling tiny food particles (as a result of steaming, boiling, frying, grating, shedding, or grinding) can potentially trigger an allergic reaction in highly sensitive people. Thus, people who are very sensitive should avoid situations in which aerosolized food could be inhaled. Although peanut protein does not easily become airborne from peanut butter, it may from peanut flour or “dusty” roasted peanuts. Similarly, touching an allergenic food and then touching the eyes, nose, or mouth can cause an allergic reaction.
LIVING WITH FOOD ALLERGIES — Adults and parents of children with food allergies must learn to carefully read food labels, prepare meals at home, and talk to others about their condition. (See “Food allergy in schools and camps”.)
Food labeling — Laws regarding food labeling vary by country. People with food allergies must consider not only a food’s ingredients, but also any potential cross-contact (also called cross-contamination) that can occur as the food is prepared. It’s also important to know that ingredients may change over time and labels should be read each time you purchase a product.
In the United States, the Food Allergen Labeling and Consumer Protection Act mandates that nutritional labels on food packages clearly identify eight specified food allergy sources (milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, and soy), although other foods may still appear under multiple names. Additionally, for tree nuts, crustacean shellfish and fish, the specific type (eg, walnut or cashew, shrimp or lobster, tuna or salmon, etc), must be labeled.
This law applies to all packaged foods manufactured in the United States and also to foods that are imported for sale in the US. However, the law does not apply to packaged fresh meat, poultry, or egg products. Updates to this law are available online from the Center for Food Safety and Applied Nutrition, a branch of the Food and Drug Administration (www.fda.gov/Food/default.htm).
As of 2006, food labels in the United States must use plain English terms. However, most clinicians still recommend learning scientific or nonspecific terms that could be used to refer to common foods (table 1 and table 2 and table 3 and table 4 and table 5 and table 6 and table 7).
Potential allergens other than the eight listed above may still be listed on food labels with unclear names (eg, garlic or sesame may be listed as a spice, natural flavor, or even an artificial flavor). If the label is unclear, call the manufacturer to clarify the ingredients.
In addition, it’s important to understand that “substitute” foods, which are used to remove fats or other components of a food, may not remove the allergenic proteins. As an example, some egg substitutes (which are lower in cholesterol) still contain egg white proteins.
Advisory labeling — A manufacturer may use certain phrases when a particular allergen is not an intended ingredient, but the ingredient may come in contact with the food during the manufacturing process. As an example, a blueberry muffin may not contain nuts, but may be made in a bakery where banana nut muffins are made. Manufacturers may use phrases such as: “may contain,” “processed in a facility with,” “manufactured on shared equipment with,” and others. There are no laws regarding when this type of label should be used.
Although manufacturers use a variety of label terms in their voluntary advisory warnings, these do not necessarily reflect the level of risk. As an example, a muffin that says that it “may contain nuts” is no more or less likely to contain nuts than a muffin that says “processed in a facility with nuts”.
Advisory labeling may help to reduce the risk of an allergic reaction, but may also significantly reduce the food choices available to people with food allergies. Most allergists recommend avoiding foods that have an advisory label because it is impossible to know the actual risk. Serious allergic reactions have occurred as a result of cross-contact.
Alcoholic beverages — Alcoholic beverages may contain allergens, including unexpected ones, such as eggs, tree nuts, and seafood. Labeling laws do not currently apply to these beverages. People with food allergies are advised to call the manufacturer if there are questions about the ingredients.
Preparing meals at home — Some families avoid bringing food allergens into the home if one person is allergic. Other families keep the food in the house but are careful to avoid cross-contact.
Avoiding cross-contact requires thoroughly cleaning utensils, cookware, glassware, storage containers, and other food preparation materials used with a food allergen before the item is used to prepare or serve “safe” meals. (See ‘Cleaning’ below.)
All members of the family, including children, must be careful if allergenic foods are brought into the house. As an example, if a child uses a knife to prepare a peanut butter and jelly sandwich, he/she could introduce peanut allergen into otherwise safe jelly and subsequently cause a reaction in a peanut-allergic sibling who eats the jelly.
Other tips for preparing meals at home include preparing the safe meal first, keeping food containers covered to prevent spills, and designating specific containers of food for the allergic person only.
Cleaning — Washing food storage containers and dishes in a dishwasher or hand washing with hot water and liquid dish soap is generally adequate to remove food allergens.
Tabletops and other surfaces may be cleaned with a household cleaner or commercial wipe. Bar or liquid soap, but not alcohol-based antibacterial hand gel, can remove peanut allergen from adults’ hands . Studies of other food allergens have not been performed, although these cleaning methods are probably adequate.
Restaurant meals — Dining out can be challenging for people with food allergies. The following tips can help to ensure that the risk of contact with a food allergen is minimized (table 8).
Nuts are sometimes served on airplanes, increasing the risk of an allergic reaction. If you are traveling with a young child, clean the tray tables and inspect the seating area for peanuts or other foods that your child might find and eat. Some airlines provide additional accommodations when requested in advance (eg, a flight where peanuts are not served).
FOOD ALLERGENS IN NON-FOOD ITEMS — Non-food items, such as medications, cosmetics, vaccines, and craft supplies may contain food ingredients. Labeling laws do not apply to these products. If there are questions about a product’s ingredients, it is often helpful to call the manufacturer.
Vaccines — Gelatin, egg, and chicken products may be used in the production of certain vaccines. (See “Allergic reactions to vaccines”.)
- Gelatin — Gelatin is included in measles, mumps, rubella (MMR), varicella, diphtheria, tetanus, acellular pertussis (DTaP), and Japanese encephalitis vaccines.
- Egg — Egg protein is present in yellow fever and influenza vaccines. Some people with egg allergies can be given the influenza vaccine safely; you should consult with your allergy specialist for guidance. (See “Influenza vaccination in individuals with egg allergy”.)
- Chicken — Chicken proteins may be present in the yellow fever vaccine.
Medications and asthma inhalers — Nonprescription and prescription medications (in tablet, capsule, and inhaler form) can contain food allergens.
- Lactose — Lactose is a sugar derived from milk. Although lactose used in medications is unlikely to contain milk proteins, some experts recommend that highly allergic patients avoid using products that contain lactose (eg, use metered dose inhalers rather than dry powder inhalers that contain lactose).
- Soy lecithin — Soy lecithin is the fatty derivative of soy, and it contains trace amounts of soy proteins. Certain asthma inhalers contain small amounts of soy lecithin, which could potentially cause an allergic reaction in a person who was highly allergic to soybeans or peanuts. You should discuss the risks and benefits of these inhalers with your healthcare provider.
- Casein — Casein is a cow’s milk protein that has been used as an anti-stick agent on latex gloves.
Cosmetics and crafts — Cosmetics may contain a variety of food-derived ingredients, including milk, nut oils, wheat, and soy. Craft items, such as modeling dough may contain wheat. Egg white is sometimes used to smooth finger-paints. If there is a question about a product’s ingredients, call the manufacturer.
PERSONAL CONTACT AND FOOD ALLERGIES — Saliva and other bodily fluids can potentially expose an allergic person to food allergens. Kissing or sharing straws, glasses, or utensils are the most likely ways that saliva may be spread from one person to another. Based upon a study of peanut butter, waiting several hours after eating an allergenic food and then eating a nonallergenic food(s) seems to reduce the level of allergen in the saliva and is suggested.
It is theoretically possible to have a food allergy reaction after other forms of contact, such as sexual intercourse or a blood transfusion. However, this type of reaction is uncommon. The partner of a person with a food allergy can consider not eating large amounts of the allergen before sex to further reduce this risk.
FOOD ALLERGY TREATMENT PLAN — Because it is not always possible to avoid food allergens, it is important to develop a plan for dealing with this type of emergency before it happens. Serious allergic reactions are often unexpected, develop suddenly, and require immediate treatment. (See “Food-induced anaphylaxis”.)
The best treatment for an anaphylactic reaction is epinephrine, which is available for self-injection. The use of epinephrine autoinjectors is discussed in detail in a separate topic. (See “Patient information: Use of an epinephrine autoinjector”.)
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed every four months on our web site (www.uptodate.com/patients).
Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient Level Information:
Patient information: Food allergy symptoms and diagnosis
Patient information: Use of an epinephrine autoinjector
Professional Level Information:
Allergic and asthmatic reactions to food additives
Clinical manifestations of food allergy: An overview
Clinical manifestations of oral allergy syndrome (pollen-food allergy syndrome)
Diagnosis and management of oral allergy syndrome (pollen-food allergy syndrome)
Diagnostic tools for food allergy
Food allergen avoidance
Food allergy in schools and camps
Future therapies for food allergy
Oral food challenges for diagnosis and management of food allergies
Primary prevention of allergic disease: Maternal avoidance diets in pregnancy and lactation
Respiratory manifestations of food allergy
Seafood allergies: Fish and shellfish
The impact of breastfeeding on the development of allergic disease
The natural history of childhood food allergy
Unique aspects of anaphylaxis in infants
Nutritional issues in food allergy
Influenza vaccination in individuals with egg allergy
The following organizations also provide reliable health information.
- Medline Plus
(www.nlm.nih.gov/medlineplus/foodallergy.html, available in Spanish)
- National Institute of Allergy and Infectious Disease
- American Academy of Allergy Asthma and Immunology
- Food Allergy and Anaphylaxis Network
- American College of Allergy, Asthma, and Immunology
- Food Allergy Initiative
- Perry TT, Conover-Walker MK, Pomés A, et al. Distribution of peanut allergen in the environment. J Allergy Clin Immunol 2004; 113:973.
- Simonte SJ, Ma S, Mofidi S, Sicherer SH. Relevance of casual contact with peanut butter in children with peanut allergy. J Allergy Clin Immunol 2003; 112:180.
- Lack G. Clinical practice. Food allergy. N Engl J Med 2008; 359:1252.
- Simons E, Weiss CC, Furlong TJ, Sicherer SH. Impact of ingredient labeling practices on food allergic consumers. Ann Allergy Asthma Immunol 2005; 95:426.
- Maloney JM, Chapman MD, Sicherer SH. Peanut allergen exposure through saliva: assessment and interventions to reduce exposure. J Allergy Clin Immunol 2006; 118:719.