Big Fish Sandwich from Burger King: allergens at a glance
The honest verdict
Big Fish Sandwich · Burger King
Burger King's Big Fish Sandwich contains fish (breaded pollock fillet) and wheat (breading and bun) as direct ingredients — anyone with a fish or wheat allergy must avoid this sandwich. Tartar sauce typically adds egg; milk may also be present in the sauce or bun. Sesame may appear on some location's bun varieties. Soy is possible via frying oil or bun formulation. Peanut, tree nut, and shellfish are not listed ingredients in this sandwich. Given that this item is fried in a busy fast-food environment, cross-contact with other allergens is possible. Always confirm the current allergen status at your specific Burger King location.
Allergen details change and vary by location. This is a general guide — always confirm with the restaurant before ordering. Not official or medical advice.
Key facts
The Big Fish Sandwich is made with a breaded Alaskan pollock fillet — a direct fish allergen source, not a cross-contact risk.
Sesame became the 9th major US food allergen in January 2023 — seeded buns at fast-food restaurants are now a labeled allergen concern.
Shared fryer oil can transfer fish protein to non-fish items — a critical risk for diners with fish allergy ordering other foods at locations that fry fish.
Every major allergen, one clear grid
Each of the nine major allergens marked for Big Fish Sandwich at Burger King — Contains, May contain (cross-contact or varies), or Free. Anything we couldn't confirm defaults to "may contain," because a shared kitchen can't be ruled out without the restaurant's official menu.
- MilkMay contain
Tartar sauce used on the Big Fish Sandwich may contain milk or dairy-derived ingredients. The bun formulation may also include milk powder in some versions. Confirm with the restaurant.
- EggMay contain
Tartar sauce is typically mayonnaise-based, which contains egg. Order without tartar sauce to reduce egg exposure, though kitchen cross-contact remains possible.
- Wheat / GlutenContains
Both the breaded fish fillet and the bun contain wheat. There is no wheat-free version of the Big Fish Sandwich.
- SoyMay contain
The frying oil may be soybean-based, and the bun may contain soy flour. Confirm frying oil and bun details with the restaurant if you have a soy allergy.
- PeanutFree
Not a listed ingredient. Burger King does not typically use peanut oil. Shared kitchen cross-contact is possible but low-risk for peanut.
- Tree NutFree
Not a listed ingredient in this sandwich.
- FishContains
The Big Fish Sandwich is a fish product — its primary component is a breaded pollock fillet. Anyone with a fish allergy must avoid this sandwich entirely. Cross-contact from this item also affects other foods prepared in the same kitchen.
- ShellfishFree
Not a listed ingredient. The fish used is pollock, a finfish — not a shellfish product. However, shared prep surfaces create some shellfish cross-contact risk at locations that handle shellfish.
- SesameMay contain
Burger King bun types vary by location. Some buns have sesame seeds on the crown. Confirm whether your location uses a sesame bun for the Big Fish Sandwich — sesame is now the 9th major US food allergen.
“May contain” means cross-contact is possible or the answer varies by location — not that the allergen is a listed ingredient. For a severe allergy, treat “may contain” the same as “contains” until the restaurant confirms otherwise.
Small changes that remove an allergen
Simple modifications that can take an allergen off your big fish sandwich. Always name your allergy when you order and ask staff to confirm — a modification only helps if the kitchen prepares it separately.
Order without tartar sauce
Ask for a plain (non-sesame) bun if available
Avoid the sandwich entirely if you have a fish allergy — there is no fish-free version
A modification lowers exposure but doesn't erase cross-contact from shared fryers, grills, or prep surfaces. For a severe allergy, confirm the prep with a manager before you eat.
Read this before you order
Cross-contact & severe allergies
A “free of” mark on the grid above means the allergen isn't an ingredient — it doesn't mean the item was made in an allergen-free kitchen. Two things matter most:
Shared fryers & equipment
The Big Fish Sandwich is fried in shared oil at Burger King locations. Other items — including chicken sandwiches, onion rings, and fries — may share the same fryer or prep surfaces. The fish fillet itself is a significant cross-contact source for nearby menu items. For chicken, burger, or other non-fish orders at the same location, ask about fryer separation.
If your allergy is severe
If you have a severe fish allergy, the Big Fish Sandwich is not safe under any modification — it is a fish product. Beyond this sandwich, the fact that it shares fryers and prep surfaces with other Burger King items means fish cross-contact may affect other foods ordered at the same location. Always carry your epinephrine auto-injector and alert restaurant staff to your fish allergy. For other severe allergies (wheat, egg), modifications reduce direct exposure but do not eliminate kitchen cross-contact.
This guidance is general and can't account for how any single location prepares your food. The restaurant's staff and official allergen menu are the final word — when in doubt, ask, or choose something else.
❓Frequently Asked Questions
Burger King's Big Fish Sandwich uses a breaded Alaskan pollock fillet. Pollock is a white fish — a finfish, not a shellfish. Anyone with a fish allergy (covering finfish like pollock, cod, or tilapia) must avoid this sandwich entirely. If you have a shellfish allergy but not a finfish allergy, pollock itself is not a shellfish — but confirm cross-contact practices with the restaurant.
No. The breaded pollock fillet uses a wheat-based breading, and the bun is made with wheat flour. There is no gluten-free version of this sandwich available at Burger King. Both components are wheat-containing, so removing one does not resolve the allergen. Anyone with celiac disease or a wheat allergy must avoid this item.
The tartar sauce served with the Big Fish Sandwich is typically mayonnaise-based, which contains egg. Ordering without tartar sauce removes the primary egg source. However, kitchen cross-contact from shared prep surfaces means trace egg is still possible. If you have a mild egg allergy, removing the sauce is usually adequate; for a severe egg allergy, ask about the full prep environment.
It may. Bun types at Burger King locations vary, and some locations use a sesame seed bun for the Big Fish Sandwich. Sesame is now the 9th major US food allergen (FASTER Act, effective January 2023). Confirm whether your specific location uses a sesame bun and whether a sesame-free alternative is available before ordering.
Yes, potentially — for other menu items ordered at the same Burger King. The Big Fish fillet shares fryer oil and prep equipment with chicken sandwiches, fries, onion rings, and other items. If someone with a fish allergy orders a non-fish item at a location that serves the Big Fish, they should ask about fryer rotation and surface practices, as fish protein can transfer through shared oil.
Related Articles
Crispy Chicken Sandwich Allergens: Big-9 Breakdown
Does a crispy chicken sandwich contain sesame, wheat, or egg? Big-9 guide: bun, batter, and condiment risks — sesame and mayo add allergens nuggets lack.
Read moreSpicy Big Bacon Cheddar Chicken Sandwich Allergens: Big-9 Breakdown
Does the Spicy Big Bacon Cheddar Chicken Sandwich contain wheat, milk, or egg? Big-9 allergen guide for this loaded chicken sandwich from a major fast-food chain.
Read moreBig Breakfast Allergens: Big-9 Breakdown
Does the Big Breakfast contain wheat, milk, or egg? Big-9 guide for McDonald's platter — biscuit, scrambled eggs, sausage, hash browns, and hotcake. Verify with your restaurant.
Read moreItalian Sandwich Allergens: Big-9 Breakdown
Does an Italian sandwich contain wheat, milk, or soy? Big-9 guide for the classic cold-cut sub — distinct from meatball, chicken parm, and toasted variants.
Read morePhilly Steak Sandwich Allergens: Big-9 Breakdown
Does a Philly Steak Sandwich contain wheat, milk, or soy? Big-9 guide for the classic cheesesteak-style sandwich — typically wheat bun, melted cheese, and grilled steak.
Read moreBig Mac Allergens: McDonald's Big-9 Breakdown
Does the Big Mac contain wheat, milk, or sesame? Big-9 allergen guide for McDonald's signature burger — bun, sauce, cheese, and cross-contact risks. Verify with your location.
Read moreFind out which foods you actually react to
Reading allergen labels is a lot easier once you know exactly what you're allergic to. Curex offers at-home allergy testing and immunotherapy so you can identify your triggers and manage them with a clinician — the confident first step before you navigate any menu.
- At-home allergy testing — no clinic visit
- Reviewed by board-certified allergists
- Know your triggers instead of guessing
Please verify before ordering
Allergen info changes and varies by location
Recipes, suppliers, and preparation methods change often and differ between locations, so the details here can go out of date or not match your specific Burger King restaurant. Always confirm directly with the restaurant and check its official allergen menu before ordering. This page is a general research summary — it is not official information from Burger King, and it is not medical advice. If you have a food allergy, decisions about what is safe to eat should be made with the restaurant and, where relevant, your healthcare provider.