Riley Keough Almost Triggered Andrew Garfield's Allergy

While filming 'Under the Silver Lake', Riley Keough ate a granola bar containing peanuts, which could have triggered a dangerous allergic reaction in Andrew Garfield

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Riley Keough never thought a granola bar could shut down a movie set — and potentially threaten her costar’s life.

But while filming the 2018 mystery-thriller Under the Silver Lake with Andrew Garfield, an innocent snack led production to a halt.

"I was in the makeup trailer and I was eating, like, a granola bar or something, and I was about to shoot a scene where I have to kiss Andrew," Keough explained to Vanity Fair.

Keough didn’t know, however, that Garfield has a severe nut allergy.

“The makeup lady was like, 'Are there peanuts in that?' “And I was like, ‘I think. I don’t know.’ ”

“And then she like, ran away,” Keough said.

The makeup artist returned with the film’s producer, who alerted the actress, 34, to Garfield’s allergy.

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"The producer came in and was like, 'Riley, Andrew's very allergic to peanuts and we have to shut the set down. They shouldn't have been at craft [services, the on-set catering], and I don't know why they're on set.' "

“I was kind of like, ‘Oh, f–, that’s crazy,” the Daisy Jones & the Six star said. “But also, like, thank God that this woman caught it, ‘cause I had no idea.”

Peanut allergies can cause the life-threatening reaction anaphylaxis, according to the Mayo Clinic, which causes the throat to swell and makes breathing difficult.

It can also cause a rapid pulse, loss of consciousness, and a drop in blood pressure.

“Peanut allergy is the most common cause of food-induced anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) autoinjector (EpiPen, Auvi-Q, others) and a trip to the emergency room,” says Mayo Clinic.

The actor’s allergy is so severe that a friend from Chile, Sebastian Aguirre, taught Garfield, 39, how to tell people he’s allergic to “all kinds of nuts” in Spanish — adding that it would lead to his “muerte” (death).

“It was actually very stressful,” Keough remembered of the tense moment. Otherwise, she said she has fond memories of the film, in which she played a woman who disappears.

“This was a very cool movie to film because it was in Los Angeles," Keough, who welcomed daughter Tupelo Storm with husband Ben Smith-Petersen last year, said. "I’ve only ever been able to film three things in Los Angeles, which is where I live.”