Filet-O-Fish: Allergens at a Glance
The honest verdict
Filet-O-Fish · McDonald's
The Filet-O-Fish is McDonald's fish sandwich featuring a breaded pollock patty, half slice of American cheese, and tartar sauce on a steamed bun. It contains wheat (bun and breading), milk (cheese and tartar sauce), fish (pollock), egg (tartar sauce), and soy (frying oil and bun). Sesame is not a listed ingredient but may be present via shared bun production. Peanut, tree nut, and shellfish are not typical ingredients. The fish patty is fried in the same oil as other menu items, creating cross-contact risks. Always confirm with your specific McDonald's location before ordering.
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 Filet-O-Fish was introduced by McDonald's in 1965 as a fish option for Catholic customers during Lent.
The fish patty is made from wild-caught Alaska pollock, a sustainable whitefish certified by the Marine Stewardship Council.
The FASTER Act (2023) added sesame as the 9th major food allergen, requiring clear labeling on packaged foods including fast-food buns.
Every major allergen, one clear grid
Each of the nine major allergens marked for Filet-O-Fish at McDonald's — 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.
| Allergen and notes | Status |
|---|---|
Milk The Filet-O-Fish includes a half slice of American cheese (milk-based) and tartar sauce which contains milk ingredients. The bun may also contain milk derivatives. Removing the cheese and tartar sauce would eliminate the primary milk sources. | Contains |
Egg Tartar sauce served on the Filet-O-Fish contains egg. The bun and fish patty breading may also contain egg or egg derivatives. Removing the tartar sauce reduces but does not eliminate egg risk. | Contains |
Wheat / Gluten The steamed bun is wheat-based, and the fish patty has a wheat-based breaded coating. Both are direct sources of wheat/gluten. There is no gluten-free bun option at McDonald's. | Contains |
Soy The fish patty is fried in refined soybean oil. The bun may contain soy flour or lecithin. Highly refined soy oil is FDA-exempt from allergen labeling and tolerated by most with soy allergy, but those with severe soy sensitivity should confirm preparation details. | May contain |
Peanut Peanut is not a listed ingredient in the Filet-O-Fish or its components. McDonald's does not use peanut oil for frying at standard US locations. | Free |
Tree Nut Tree nuts are not an ingredient in the Filet-O-Fish bun, fish patty, cheese, or tartar sauce. | Free |
Fish The Filet-O-Fish patty is made from wild-caught pollock (Alaskan pollock). This is a direct fish allergen source. The fish is breaded and fried, so the fish protein is present throughout the patty. | Contains |
Shellfish Shellfish is not an ingredient in the Filet-O-Fish. The pollock patty is a finfish, not shellfish. Cross-contact with shellfish is very unlikely in McDonald's kitchens. | Free |
Sesame Sesame is not a listed ingredient in the Filet-O-Fish bun at McDonald's US locations. However, sesame seeds or sesame flour may be used in bun production at shared facilities, and McDonald's has noted sesame cross-contact risk on buns. The FASTER Act (2023) requires sesame labeling, so check the McDonald's allergen menu for the most current bun formulation. | May contain |
“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 filet-o-fish. Always name your allergy when you order and ask staff to confirm — a modification only helps if the kitchen prepares it separately.
Order the Filet-O-Fish without cheese
Order the Filet-O-Fish without tartar sauce
Request a bun that is not steamed in shared equipment
Ask for the fish patty cooked in a dedicated fryer (if available)
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 fish patty is fried in shared fryer oil at McDonald's locations. This means the oil may contain trace proteins from chicken nuggets, chicken sandwiches, fries, hash browns, and other fried items. The bun steamer may also be shared with other bun types. Cross-contact with wheat, milk, egg, and soy is possible through shared cooking surfaces, utensils, and prep areas. The Filet-O-Fish is prepared in the same kitchen area as all other McDonald's menu items.
If your allergy is severe
For anaphylactic allergy to fish, wheat, milk, or egg, the Filet-O-Fish presents multiple direct allergen sources plus cross-contact risks. The fish patty is a direct fish allergen — there is no fish-free version of this sandwich. Shared fryers mean trace wheat, milk, and egg from other items may be present in the cooking oil. Carry your epinephrine auto-injector. If you cannot confirm preparation details with the specific McDonald's location, consider a non-fish alternative from a restaurant with dedicated fryers.
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.
Avoidance is not the only option for milk allergy
There is no FDA-approved immunotherapy for milk allergy. Some specialist centres offer milk oral immunotherapy off-label, and Xolair is approved to reduce the severity of reactions to accidental exposure across IgE-mediated food allergies.
Beyond that, oral immunotherapy in a specialist clinic raises reaction thresholds the most of any current approach, and sublingual immunotherapy raises them less but causes markedly fewer reactions and is easier to keep up over years. Neither makes any particular dish safe to eat, and an epinephrine auto-injector stays with you throughout.
A history of anaphylaxis, or severe or poorly controlled asthma alongside the food allergy, means this belongs with an in-person allergist rather than any remote service.
Frequently Asked Questions
No. The Filet-O-Fish contains wheat in both the bun and the breaded fish patty. There is no gluten-free bun option at McDonald's, and the fish patty breading is wheat-based. The sandwich is not suitable for a gluten-free or wheat-free diet. Cross-contact from shared fryers also introduces additional wheat risk.
Yes. The Filet-O-Fish contains milk from the American cheese slice and the tartar sauce. The bun may also contain milk derivatives. To reduce dairy, order without cheese and without tartar sauce, but the bun may still contain milk. The fish patty itself is typically dairy-free by ingredient.
The Filet-O-Fish patty is made from wild-caught Alaska pollock (also known as walleye pollock). This is a white, flaky finfish. It is not shellfish. The pollock is breaded and fried. For those with fish allergy to specific species, pollock is a common whitefish and may cross-react with cod, haddock, and other gadiform fish.
Yes, at most McDonald's locations, the Filet-O-Fish patty is fried in the same oil as Chicken McNuggets, McChicken patties, and other breaded items. This means the oil may contain trace proteins from chicken, wheat, and other allergens. If you have a chicken or wheat allergy, this shared fryer is a cross-contact concern. Some locations may have dedicated fryers — ask your specific McDonald's.
Sesame is not a listed ingredient in the Filet-O-Fish bun at McDonald's US locations as of 2024. However, McDonald's has acknowledged that sesame may be present in buns due to shared production facilities. The FASTER Act (effective January 2023) requires sesame to be labeled as an allergen, so check the McDonald's allergen menu for the most current bun formulation. If you have a sesame allergy, confirm with the restaurant before ordering.
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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.
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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 McDonald's 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 McDonald's, 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.
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