RESEARCH · ALLERGY REFERENCE

Which fast food chains fry in peanut oil?

Only one major chain still fries fries in pure peanut oil — Five Guys. Chick-fil-A switched their fries to canola oil in 2002, though chicken at Chick-fil-A is still cooked in peanut oil in a separate fryer. Every other chain on Frypedia uses a vegetable oil blend, a single-source seed oil, or beef tallow — not peanut. For most peanut allergy sufferers, refined peanut oil is generally safe (per FDA labeling exemption), but severe allergies still warrant caution. Full breakdown below.

Chain Peanut oil status Architecture
Five Guys 100% refined peanut oil for fries (and everything else) Single fryer, single oil — peanut. Free peanuts in the lobby.
Chick-fil-A Refined peanut oil for chicken only; canola for fries Two physically distinct fryers. Fries in one, chicken in the other.
That's the entire list of major U.S. chains Every other chain on Frypedia — including the most-asked-about ones like Smashburger, Taco Bell, BurgerFi, Chicken Express, Popeyes, and KFC — uses a vegetable oil blend or single-source seed oil with no peanut content. Popeyes specifically is canola/soybean blend (a common point of confusion since Popeyes is a fried-chicken chain, but the oil is not peanut). KFC same story. Chicken Express uses an unspecified vegetable blend (sometimes lard at certain locations) with no peanut. The peanut oil universe in U.S. fast food is essentially these two chains.

Refined vs unrefined peanut oil — what allergy sufferers should know.

The key distinction in peanut allergy safety is refined vs unrefined (cold-pressed, expeller-pressed, or extruded) peanut oil. Both Five Guys and Chick-fil-A use the refined form. Refined peanut oil goes through a high-heat process that destroys the peanut proteins responsible for triggering allergic reactions. The FDA exempts refined peanut oil from food allergen labeling under FALCPA on this basis — the protein content is below the threshold for triggering a typical allergic response.

For most peanut-allergic individuals, refined peanut oil is well-tolerated. Multiple peer-reviewed studies (notably Hourihane et al., 1997, and subsequent work) found that even highly peanut-allergic patients did not react to refined peanut oil under controlled conditions. Allergy organizations including the American Academy of Allergy, Asthma & Immunology generally consider it safe for most patients.

However: this is averages, not absolutes. A small minority of peanut allergy sufferers do react to refined peanut oil, particularly those with severe anaphylactic histories. The standard medical guidance is: if your allergy is severe, avoid all peanut oil regardless of refining; if your allergy is mild-to-moderate and you've never reacted to refined peanut oil before, it's probably safe. Always consult your allergist for personal guidance — Frypedia is not medical advice.

Cross-contact is the secondary concern. At Five Guys, the peanut presence is explicit and unavoidable: the lobby has open buckets of free shell peanuts, and the cooking oil is peanut. The chain does not pretend otherwise — their messaging treats peanut allergy diners as "do not eat here." At Chick-fil-A, the peanut oil for chicken is in a different fryer than the canola oil for fries, but airborne peanut protein is plausible inside the kitchen. The chain marks chicken items as containing peanut on its allergen disclosure; the fries are not so marked.

Why almost every chain switched away from peanut oil.

For most of the 20th century, peanut oil was a common fast-food frying medium — high smoke point, neutral flavor, stable in the fryer. The shift away started in the 1990s as peanut allergy rates rose sharply (roughly tripling in U.S. children between 1997 and 2008 per CDC tracking) and as fast-food chains became more cautious about menu-wide allergen exposure.

Chick-fil-A's 2002 fry switch from peanut to canola was the most prominent move — the chain wanted the fry product to be accessible to peanut-allergy diners while keeping the chicken's signature flavor. The compromise was the dual-fryer architecture, which was unusual at the time and remains unusual today. Most chains that switched away from peanut just replaced it entirely with vegetable blend.

Five Guys went the other direction. The chain made peanut oil a brand commitment in the 1980s and never wavered — even as peanut allergies became more public and other chains capitulated. The stated rationale: flavor and texture. Critics: peanut oil is cheaper than other refined seed oils when bought in bulk. Whatever the actual reason, Five Guys is now the lone holdout in the national-chain category.

FAQ

Is Five Guys peanut oil refined?
Yes. Five Guys uses 100% refined peanut oil. Refined peanut oil has been processed at high temperature, which destroys the peanut proteins (Ara h 1, Ara h 2, Ara h 3) that cause allergic reactions. The FDA exempts refined peanut oil from food allergen labeling under FALCPA on this basis. For most peanut-allergic individuals, the oil itself is generally tolerated — but the lobby peanut buckets and the airborne peanut protein in the kitchen are independent concerns.
Can I eat at Five Guys with a peanut allergy?
The standard medical guidance is no — the cooking medium is peanut oil, the lobby has open peanut buckets, and the kitchen is saturated with peanut protein. Even if you tolerate refined peanut oil itself, the airborne and cross-contact exposure at a Five Guys location is a genuine concern for severe peanut allergy. The chain doesn't recommend that peanut-allergic patrons eat there. If you have a mild peanut allergy and your allergist has cleared refined peanut oil for you, the oil itself isn't the problem; the environment is.
Does Chick-fil-A use peanut oil?
Yes — for the chicken. Chick-fil-A uses refined peanut oil for chicken in a fryer dedicated to chicken products. The fries use canola oil in a physically separate fryer. The chain switched the fries to canola in 2002 to reduce peanut exposure for fry diners. Whether the chain is safe for peanut-allergic patrons depends on how strict your allergist's guidance is — the airborne peanut protein in the kitchen is non-trivial.
Does Smashburger use peanut oil?
No. Smashburger uses a beef tallow and canola oil blend — no peanut content. (The chain is in the Tallow Club, not the peanut oil category.)
Does Taco Bell use peanut oil?
No. Taco Bell uses canola oil for cooking, with a vegetable oil blend in some preparation steps. No peanut oil in the fryer. Taco Bell's broader menu is also free of peanut as a major ingredient (with the standard caveat that any fast-food kitchen could have incidental cross-contact).
Does Popeyes use peanut oil?
No. Popeyes uses a canola/soybean vegetable oil blend across its menu — including for the fries and the chicken. This is a common point of confusion because Popeyes is a fried-chicken chain and the chicken-fryer category historically used peanut oil; but Popeyes itself does not.
Does Chicken Express use peanut oil?
No. Chicken Express does not publicly document its frying oil, but reports from patrons and franchisees indicate a vegetable oil blend at most locations (sometimes lard at others, also not peanut). The chain has not publicly disclosed peanut oil use anywhere in its preparation. For severe peanut allergy diners, confirm with the specific location before ordering.
Does BurgerFi use peanut oil?
No. BurgerFi uses a vegetable oil blend (no trans fats per the chain's sourcing commitments). Not peanut-oil based.
Does Burger King use peanut oil?
No. Burger King uses a vegetable oil blend (soybean, canola, palm, cottonseed) with no peanut content. Burger King is generally considered acceptable for peanut allergy diners; the standard fast-food kitchen cross-contact caveats still apply.
Does McDonald's use peanut oil?
No. McDonald's U.S. fries use a vegetable oil blend of canola, corn, soybean, and hydrogenated soybean — no peanut. McDonald's stopped using peanut oil decades ago. The chain considers itself peanut-conscious, with allergen disclosures explicitly listing peanut-free preparation for the standard menu.
When did Chick-fil-A stop using peanut oil for fries?
In 2002. Chick-fil-A switched the fries from peanut oil to canola oil while keeping peanut oil for the chicken. The motivation was to make the Waffle Fries accessible to peanut allergy diners (and to Jewish diners observing certain dietary norms). The chicken kept peanut oil because the chain's flavor profile depends on it. The dual-fryer architecture — fries in canola, chicken in peanut, in physically distinct fryers — has been the standard since.
Why does Five Guys still use peanut oil when so many chains have switched?
Brand commitment. Five Guys' founders, Jerry and Janie Murrell, made peanut oil a defining feature in the 1980s and have never moved off it. The stated rationale is taste and texture: peanut oil has a high smoke point, neutral flavor, and a particular crisping behavior the chain considers part of its product identity. The chain accepts that this excludes peanut-allergic diners from the customer base — an unusual stance for a national chain in 2026, but a deliberate one. Free peanuts in the lobby reinforce the positioning.
Are refined peanut oil and unrefined peanut oil different for allergy purposes?
Yes — significantly. Refined peanut oil (the kind used in fast food) goes through high-heat processing that destroys the peanut proteins responsible for allergic reactions. The FDA exempts it from food allergen labeling under FALCPA on this basis. Unrefined peanut oil (cold-pressed, expeller-pressed, extruded, gourmet-grade) retains the proteins and is treated as a peanut allergen, requiring labeling. Five Guys and Chick-fil-A both use the refined form. If you find unrefined peanut oil in a fast-food kitchen, that's unusual and would be a different safety calculus.

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Frypedia is an editorial reference, not medical advice. For peanut allergy management, consult an allergist.