What are the 9 major food allergens in the US?

The FDA recognizes 9 major food allergens that account for the majority of serious food allergic reactions: milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. Sesame was added as the 9th major allergen effective January 1, 2023, under the FASTER Act of 2021. These 9 allergens must be clearly labeled on packaged foods under federal law. Outside the US, some countries have different lists — the EU recognizes 14 major allergens, adding celery, mustard, lupine, mollusks, and sulfites. Food handler training and exam materials should reference the current list of 9.

What is cross-contact and how is it different from cross-contamination?

Cross-contact is the transfer of an allergen protein from one food to another through shared utensils, surfaces, equipment, oil, hands, or direct contact. Cross-contamination is the transfer of harmful microorganisms (bacteria, viruses) between foods. They sound similar but are different in important ways. Cooking can kill bacteria (resolves cross-contamination), but cooking does NOT destroy allergen proteins (does not resolve cross-contact). This means a chicken cooked on a grill previously used for shrimp still carries shellfish protein and is dangerous to a shellfish-allergic customer. Cross-contact prevention requires separate utensils, surfaces, equipment, and processes — cooking will not save you. This is one of the most-tested concepts on food handler exams.

Does cooking destroy food allergens?

No, cooking does not destroy food allergens. While heat kills most bacteria (eliminating bacterial cross-contamination), high heat does not denature allergen proteins to safe levels. A food cooked at any temperature that came into contact with an allergen still carries that allergen and can cause an allergic reaction. This means cross-contact contamination is permanent for that batch of food — you cannot cook it out. Prevention of contact is the only safe approach: separate utensils, surfaces, cooking equipment, and cooking oil. This is one of the most consequential misconceptions in food service and one of the most heavily tested topics on food handler exams.

What should a food handler do if a customer says they have a food allergy?

When a customer informs you of a food allergy, the standard procedure is: (1) confirm the specific allergen and ask any clarifying questions; (2) verify the dish is achievable without the allergen — some dishes simply cannot be made allergen-free; (3) communicate the allergy to the kitchen using your operation's allergy alert procedure; (4) the kitchen handler should wash hands, change gloves, use clean utensils, use clean surfaces, and use clean cooking equipment; (5) plate the dish separately and have the same server (or designated allergen-aware server) deliver; (6) verbally confirm to the customer that the dish is allergen-free; (7) check in after the meal. If anything is uncertain, ask management before serving — do not guess. Treating allergen orders with full procedures is one of the most important responsibilities of food service staff.

What are the signs of a food allergic reaction?

Food allergic reactions range from mild to life-threatening. Mild signs include itching of the mouth or skin, hives, mild swelling, and stomach cramps. Moderate reactions include more severe hives, nausea, vomiting, diarrhea, difficulty breathing, and throat tightness. Severe reactions (anaphylaxis) include severe difficulty breathing or wheezing, significant swelling of the face/throat/lips/tongue, rapid drop in blood pressure, and loss of consciousness. Anaphylaxis can be fatal within minutes without emergency treatment with epinephrine and medical attention. If a customer shows any signs of a reaction in your establishment, take it seriously, ask if they have epinephrine, call 911 for moderate-to-severe symptoms, and have someone stay with them until emergency services arrive. Don't dismiss early symptoms — they can rapidly progress.

Why is shared cooking oil a critical allergen risk?

Shared cooking oil is one of the most overlooked cross-contact risks in food service. When a fryer cooks foods containing allergens (breaded shrimp, breaded fish, breaded chicken with seasoning containing dairy), trace allergen proteins enter the oil. Subsequent foods cooked in that same oil — even foods that don't appear to contain the allergen — now carry that allergen protein. French fries cooked in shellfish-contaminated oil are dangerous to a shellfish-allergic customer despite containing no shellfish themselves. This is heavily tested on food handler exams. Best practice is to have dedicated allergen-free fryers for high-allergen menus. Where dedicated fryers aren't possible, the operation should inform customers about shared oil and let them decide whether to proceed. Filtering or temperature does not remove the risk — only fresh, uncontaminated oil is safe.

Food Allergen Procedures for Servers and Cooks

TL;DR

Food allergen procedures protect customers with food allergies from potentially life-threatening reactions. In the US, the FDA recognizes 9 major food allergens that account for the majority of serious food allergic reactions: milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame (sesame was added effective January 2023 under the FASTER Act). For food handlers, the core procedures are: understanding what's in every dish, preventing cross-contact (allergen residue transferring between foods through shared surfaces, utensils, or oil), communicating clearly with customers about ingredients and risk, and knowing the emergency response if a customer has a reaction. Food handler exams test allergen-related knowledge in multiple formats: identifying the 9 major allergens, understanding what cross-contact means (different from cross-contamination), knowing how to handle special orders, recognizing signs of an allergic reaction, and responding appropriately. Allergen-related illnesses can be severe — anaphylaxis can be fatal within minutes — so handler procedures around allergens are among the highest-priority skills in food service.

The 9 Major Food Allergens (US FDA)

The FDA designates 9 major food allergens that account for the vast majority of severe allergic reactions in the United States. These are the allergens that must be clearly labeled on packaged foods under federal law:

Milk (including dairy products)
Eggs
Fish (e.g., bass, flounder, cod, tuna, salmon)
Crustacean shellfish (e.g., shrimp, crab, lobster, crayfish)
Tree nuts (e.g., almonds, cashews, pecans, walnuts, pistachios, Brazil nuts)
Peanuts (botanically a legume, not a nut — but treated as a major allergen)
Wheat (including all wheat-based products)
Soybeans (including soy sauce, tofu, edamame, soybean oil in many forms)
Sesame (added effective January 1, 2023 under the FASTER Act of 2021)

These 9 cause the majority of serious allergic reactions in the US. Food handler training programs like ServSafe and exam materials should reference all 9 — older training materials may show only 8 (excluding sesame), but updated 2023+ materials must include sesame.

Outside the US: Some countries have different allergen lists. The EU recognizes 14 major allergens (adding celery, mustard, lupine, mollusks, and sulfites). Always check local regulations.

What Is an Allergic Reaction?

A food allergy is an immune system response to a protein in food. When someone with an allergy is exposed to that protein, their immune system overreacts, treating it as a threat. Reactions range from mild to life-threatening:

Mild reactions:

Itching in the mouth or skin
Hives or skin rash
Stomach cramps
Mild swelling

Moderate reactions:

More severe hives or swelling
Nausea, vomiting, diarrhea
Difficulty breathing
Throat tightness

Severe reactions (anaphylaxis):

Severe difficulty breathing or wheezing
Significant swelling (face, throat, lips, tongue)
Rapid drop in blood pressure
Loss of consciousness
Can be fatal within minutes without emergency treatment

Anaphylaxis is a medical emergency. Even trace amounts of an allergen can trigger anaphylaxis in someone with a severe allergy. This is why allergen procedures matter so intensely in food service — a tiny mistake can have life-or-death consequences.

Cross-Contact: The Key Allergen Concept

Cross-contact is the transfer of an allergen from one food to another through:

Shared utensils (using the same knife on multiple foods)
Shared cooking surfaces (a grill that cooked shrimp now cooking chicken)
Shared cooking oil (frying french fries in the same oil used for shrimp)
Direct contact (a customer's salad with peanuts dropped on a peanut-free salad)
Airborne particles (flour dust from a pizza station settling on other foods)
Hand contamination (handler touching peanuts then preparing a peanut-free dish without washing hands)

Cross-contact is NOT the same as cross-contamination. They sound similar but are different:

Cross-contamination: Transfer of harmful microorganisms (bacteria, viruses) between foods, surfaces, or utensils. Concerns pathogens like the Big Six reportable illnesses.
Cross-contact: Transfer of an allergen between foods. Concerns proteins, even in trace amounts.

Why this matters: cooking kills most bacteria (resolves cross-contamination risk), but cooking does NOT destroy allergen proteins. Cross-contact contamination survives all normal cooking temperatures — including the cooking temperatures handlers rely on to escape the temperature danger zone. A shrimp cooked on a grill that left protein residue, then a chicken cooked on the same grill afterward — the chicken now carries shrimp protein, and a shrimp-allergic customer eating the chicken can have a severe reaction.

This distinction is heavily tested on food handler exams.

Standard Allergen Procedures for Food Handlers

When a customer informs the server that they have a food allergy, the entire kitchen and serving operation should follow specific procedures. The standard sequence:

Step 1: Server Receives the Allergy Information

Listen carefully and confirm the specific allergen
Note any specific concerns (severity, history of anaphylaxis)
Inform the customer that the order will be handled with allergen procedures

Step 2: Server Communicates to Kitchen Immediately

Use the operation's standard "allergy alert" procedure (verbal callout, ticket marking, etc.)
Specify which allergen and what dish
Verify the dish is achievable without the allergen (some dishes cannot be made allergen-free)

Step 3: Kitchen Handler Prepares the Order Separately

Wash hands thoroughly and change gloves
Use clean utensils (different from those used for the allergen)
Use clean preparation surfaces (clean or use a separate area)
Use clean cooking equipment (clean grill area, separate fryer if needed, fresh cooking oil for fried foods)
Avoid touching the allergen between steps
Use color-coded "allergen-free" tools where the operation provides them

Step 4: Special Plating and Delivery

Plate the allergen-free dish on dedicated allergen-free plate (if used)
Mark or flag the order as "allergy-safe"
Have the same server (or a designated allergen-aware server) deliver
Verbally confirm to the customer that the dish is allergen-free

Step 5: Document and Follow Up

Note the customer's allergen on the order ticket or notes
After the meal, check in with the customer
If a reaction occurs, respond immediately (see emergency response below)

Dedicated vs Shared Equipment

For operations that handle frequent allergy orders, some have dedicated allergen-free equipment:

Dedicated approach:

Separate cutting boards (color-coded, often purple for allergens)
Separate prep surfaces
Separate fryers for allergen-free items
Separate utensils stored separately
Dedicated allergen-safe pans

Shared equipment with thorough cleaning:

Same equipment used for both allergen and non-allergen items
Thoroughly cleaned and sanitized between uses
More risk of cross-contact if cleaning is rushed

Best practice: Operations with frequent allergy orders should invest in dedicated equipment when possible. Operations with occasional allergy orders should use thorough cleaning procedures and verify with management before handling allergy orders.

Shared Cooking Oil — A Critical Risk

One of the most overlooked cross-contact risks is shared cooking oil, particularly in fryers:

A fryer used for breaded shrimp transfers shellfish protein into the oil
French fries cooked in that same oil now carry shellfish protein
A shellfish-allergic customer eating the fries can have a severe reaction

Procedures to manage fryer cross-contact:

Dedicated fryer for allergen-sensitive orders, such as a dedicated gluten-free fryer or a fryer that has not been used for shellfish, breaded items, or other declared allergens
Fresh oil rotation before allergen-free orders (rarely practical mid-shift)
Pre-screening orders: If shared oil is unavoidable, inform the customer and let them decide whether to proceed

This is a critical exam topic: candidates should understand that "same oil" means "contaminated for allergy purposes" regardless of temperature or filtering.

Cooking Doesn't Destroy Allergens

A critical food safety fact: cooking does not destroy allergen proteins.

High heat kills bacteria (resolves microbial contamination)
High heat does NOT denature allergen proteins to safe levels
A grilled chicken cooked on a shrimp-contaminated grill is still dangerous to a shrimp-allergic customer
Boiling water with traces of an allergen still contains the allergen protein

The implication: prevention of contact is the only safe approach. You cannot "cook out" an allergen risk after cross-contact has occurred.

This is one of the most consequential misconceptions in food service. Many handlers (and customers) believe that cooking destroys allergens — it doesn't.

Emergency Response: If a Customer Has a Reaction

If a customer shows signs of an allergic reaction in your establishment:

Immediate Actions

Take the situation seriously — do not assume it's mild
Ask if they have epinephrine (EpiPen or similar) — if yes, encourage them to use it and follow your workplace emergency policy. Assist only if you are trained, permitted, and the customer cannot self-administer.
Call 911 immediately for moderate-to-severe reactions, especially:
- Difficulty breathing
- Throat tightness
- Significant swelling
- Loss of consciousness
Have someone stay with the customer until emergency services arrive
Note what they ate — provide this information to emergency responders

Don't Do

Don't tell the customer to drink water or eat something — this won't help and can complicate medical response
Don't move the customer unless they're in immediate danger
Don't dismiss symptoms — even early signs can rapidly progress to anaphylaxis
Don't assume customer knows what to do — even people with severe allergies can panic in a reaction

Document the Incident

Record what was ordered and what was served
Note any handling procedures that may have failed
Report to management immediately
Preserve any remaining food for testing if appropriate

Special Dietary Requests vs Allergies

Servers must distinguish between preference and allergy:

Preference	Allergy
"I don't like peanuts"	"I'm allergic to peanuts"
"No dairy please"	"I have a severe dairy allergy"
"Hold the gluten"	"I have celiac disease"
"Cooked without seafood"	"I have an anaphylactic shellfish allergy"

Allergies require full allergen procedures; preferences are dietary requests. When in doubt, ask: "Is this a preference, or a medical allergy I need to flag for the kitchen?"

However: treat ambiguous requests as allergies until clarified. Better to apply allergen procedures unnecessarily than to risk a reaction.

Common Mistakes and Misconceptions

"Allergies and food intolerances are the same." False. Allergies trigger an immune system response and can be life-threatening. Intolerances (like lactose intolerance) cause digestive discomfort but are not immune reactions. Both require attention, but allergies require strict allergen procedures.
"A little bit of an allergen is fine." False for severe allergies. Trace amounts can trigger anaphylaxis in some patients. Treat any amount as dangerous.
"Cooking destroys allergens." False. Heat does not denature allergen proteins. Cross-contact contamination survives cooking. Prevention of contact is the only safe approach.
"Peanut allergy means just no peanuts." False (sometimes). Peanut-allergic patients can also react to tree nuts, peanut oil residue, and foods processed in shared facilities. Always verify with the customer and follow strict cross-contact procedures.
"The customer is responsible for knowing what's in the food." Partially true. Customers should communicate their allergies, but the food handler is responsible for ensuring the dish is prepared without the allergen and that allergen procedures are followed.
"Refined oils are allergen-free." Generally false in food service context. Even refined oils may contain trace allergen proteins, and most operations cannot verify oil purity. Treat any oil shared with allergen-containing foods as contaminated.
"Wiping down a surface removes allergens." Insufficient. Wiping alone does not reliably remove all allergen proteins. Surfaces require thorough cleaning and sanitizing — and ideally dedicated allergen-free preparation areas.

Sesame: The Newest Major Allergen

The FASTER Act of 2021 (Food Allergy Safety, Treatment, Education, and Research Act) added sesame as the 9th major allergen, effective January 1, 2023.

Why this matters:

Sesame is now legally required to be labeled on packaged foods
Food handlers must be aware of sesame in dishes
Older training materials may not include sesame
Sesame appears in many foods: tahini, sesame oil, sesame seeds on bread, halva, hummus, and many Asian dishes

For the exam: Make sure your study materials are current (2023 or later) to include sesame. Older training may show only 8 major allergens — the current list includes sesame.

Frequently Asked Questions

What are the 9 major food allergens in the US?: The FDA recognizes 9 major food allergens that account for the majority of serious food allergic reactions: milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. Sesame was added as the 9th major allergen effective January 1, 2023, under the FASTER Act of 2021. These 9 allergens must be clearly labeled on packaged foods under federal law. Outside the US, some countries have different lists — the EU recognizes 14 major allergens, adding celery, mustard, lupine, mollusks, and sulfites. Food handler training and exam materials should reference the current list of 9.
What is cross-contact and how is it different from cross-contamination?: Cross-contact is the transfer of an allergen protein from one food to another through shared utensils, surfaces, equipment, oil, hands, or direct contact. Cross-contamination is the transfer of harmful microorganisms (bacteria, viruses) between foods. They sound similar but are different in important ways. Cooking can kill bacteria (resolves cross-contamination), but cooking does NOT destroy allergen proteins (does not resolve cross-contact). This means a chicken cooked on a grill previously used for shrimp still carries shellfish protein and is dangerous to a shellfish-allergic customer. Cross-contact prevention requires separate utensils, surfaces, equipment, and processes — cooking will not save you. This is one of the most-tested concepts on food handler exams.
Does cooking destroy food allergens?: No, cooking does not destroy food allergens. While heat kills most bacteria (eliminating bacterial cross-contamination), high heat does not denature allergen proteins to safe levels. A food cooked at any temperature that came into contact with an allergen still carries that allergen and can cause an allergic reaction. This means cross-contact contamination is permanent for that batch of food — you cannot cook it out. Prevention of contact is the only safe approach: separate utensils, surfaces, cooking equipment, and cooking oil. This is one of the most consequential misconceptions in food service and one of the most heavily tested topics on food handler exams.
What should a food handler do if a customer says they have a food allergy?: When a customer informs you of a food allergy, the standard procedure is: (1) confirm the specific allergen and ask any clarifying questions; (2) verify the dish is achievable without the allergen — some dishes simply cannot be made allergen-free; (3) communicate the allergy to the kitchen using your operation's allergy alert procedure; (4) the kitchen handler should wash hands, change gloves, use clean utensils, use clean surfaces, and use clean cooking equipment; (5) plate the dish separately and have the same server (or designated allergen-aware server) deliver; (6) verbally confirm to the customer that the dish is allergen-free; (7) check in after the meal. If anything is uncertain, ask management before serving — do not guess. Treating allergen orders with full procedures is one of the most important responsibilities of food service staff.
What are the signs of a food allergic reaction?: Food allergic reactions range from mild to life-threatening. Mild signs include itching of the mouth or skin, hives, mild swelling, and stomach cramps. Moderate reactions include more severe hives, nausea, vomiting, diarrhea, difficulty breathing, and throat tightness. Severe reactions (anaphylaxis) include severe difficulty breathing or wheezing, significant swelling of the face/throat/lips/tongue, rapid drop in blood pressure, and loss of consciousness. Anaphylaxis can be fatal within minutes without emergency treatment with epinephrine and medical attention. If a customer shows any signs of a reaction in your establishment, take it seriously, ask if they have epinephrine, call 911 for moderate-to-severe symptoms, and have someone stay with them until emergency services arrive. Don't dismiss early symptoms — they can rapidly progress.
Why is shared cooking oil a critical allergen risk?: Shared cooking oil is one of the most overlooked cross-contact risks in food service. When a fryer cooks foods containing allergens (breaded shrimp, breaded fish, breaded chicken with seasoning containing dairy), trace allergen proteins enter the oil. Subsequent foods cooked in that same oil — even foods that don't appear to contain the allergen — now carry that allergen protein. French fries cooked in shellfish-contaminated oil are dangerous to a shellfish-allergic customer despite containing no shellfish themselves. This is heavily tested on food handler exams. Best practice is to have dedicated allergen-free fryers for high-allergen menus. Where dedicated fryers aren't possible, the operation should inform customers about shared oil and let them decide whether to proceed. Filtering or temperature does not remove the risk — only fresh, uncontaminated oil is safe.

Bottom Line

Food allergen procedures protect customers from potentially life-threatening reactions. The 9 major US food allergens are milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame (sesame added January 2023). Food handlers must understand cross-contact — allergen transfer between foods through shared utensils, surfaces, equipment, oil, or hands — and recognize that cooking does not destroy allergens, so prevention of contact is the only safe approach. Standard allergen procedures involve thorough handwashing, gloves, dedicated or thoroughly cleaned utensils and surfaces, fresh or dedicated cooking oil, careful preparation and plating, and clear verbal confirmation to the customer. Anaphylaxis is a medical emergency that can be fatal within minutes; recognize symptoms, encourage use of epinephrine, and call 911 immediately. On the food handler exam, allergen topics test knowledge of the 9 major allergens, cross-contact vs cross-contamination distinction, proper handling procedures, and emergency response. These skills can save lives. For the broader cluster, see the complete ServSafe Food Handler exam guide.

Source: FDA Food Allergies · ServSafe (National Restaurant Association) · FDA Food Code