What Makes The Carl's Jr. El Diablo Burger So Spicy?

Fast food restaurants have been adding more spicy items to their menus, getting attention with often limited time offerings that up the heat ante, like the fiery ghost pepper chicken sandwich and fries Wendy's once had. Carl's Jr. entered the fray with its El Diablo burger — "The Devil" if you didn't pay attention in Spanish class. The burger packs heat in several ways, layering hot pepper flavor to create a mouth-tingling spiciness.

The El Diablo is made with Carl's Jr.'s charbroiled all-beef burgers (it's one of the few fast food restaurants that actually cook their burgers on a grill), bacon, jalapeno poppers, pepperjack cheese, jalapeno coins, and habanero ranch sauce on a seeded bun. That's four forms of spicy peppers, three of them jalapenos. The poppers are fried cheddar cheese and jalapeno bites, which are one of the chain's more popular sides. Carl's Jr. doesn't post ingredients, but pepperjack cheese is usually studded with jalapenos, although other peppers can be used too. The jalapeno coins are slices which some reviewers have said are probably pickled.

The three types of jalapeno on offer all heat up the El Diablo, but the habanero in the sauce is even hotter. Jalapenos typically range from 2,500 to 8,000 Scoville heat units (SHU), while Habaneros offer anywhere from 150,000 to 570,000 SHU. The sauce's ranch cools things down a bit, but that's still a lot of heat piled on.

The El Diablo first debuted in 2015 for a limited time. It occasionally reappeared over the following years until it became a permanent addition in April of 2024. When Carl's Jr. made it a regular item, it also introduced an El Diablo Chicken Tender Wrap and El Diablo Loaded Fries, but they're no longer on the menu.

The spicy burger was actually dreamed up by Carl's Jr.'s advertising agency. It was asked by company owner CKE Restaurants to create a burger that would appeal to the large Hispanic market in the southwestern United States, an important area for the West Coast-based chain. Research shows 56% of American households have hot sauce in the refrigerator, so it's no real surprise the El Diablo did well in tasting, after which the brand decided to release it nationally.

Carl's Jr. brought the heat with its El Diablo — which also comes as a double or triple — but it doesn't sell that many other spicy items. The Big Angus El Diablo is the same burger but with a ⅓-pound, 100% Angus Beef patty. There's also a Spicy Chicken Sandwich on the menu. The Hangover Helper breakfast burger meal which we put to the ultimate test has a spicy version. It adds pepperjack cheese and guacamole to a burger typically topped with egg, bacon, and Hash Rounds. It then swaps in jalapeno popper bites, Carl's Jr.'s only side with any heat, for the Hash Rounds.