Famed British adventure-seeker Bear Grylls has survived cliff climbs, running through forest fires and wrestling crocodiles — but an allergic reaction from a bee sting almost knocked him out as he filmed his latest series, according to a new report.

The 45-year-old former military man was on a boat recording his upcoming show “Treasure Island” on a remote Pacific island when he was stung by a bee, The Daily Star reported. The sting soon sent him into a “life-threatening” anaphylactic shock.

Islander Mano Shanmug-anathan, a brain surgeon, said he was stunned to see the survival expert suffer such a severe reaction.

“I think that Bear is an impressive guy,” Shanmug-anathan told the Star. “He understands his tasks at hand and knows what he has to achieve.”

Bear tried to continue with the shoot — but it became impossible as his condition worsened. Medics rushed on the boat and treated Grylls with an EpiPen to counteract the venom, according to the report.

“The irony of Bear the survivalist being stung, having the potential of an allergic reaction, and needing to be treated with an EpiPen, was a bizarre moment,” the islander added. “That was crazy!”

Grylls discovered his bee allergy when he was stung by one in 2008, as he cut honeycomb from a nest, The Evening Standard reported.

The “Treasure Island” series, which launches next month, follows strangers as they try to survive on a remote island for a month — with about $122,000 up for grabs, according to the Star.

The adventurers must choose whether to keep the money to themselves or share it with others.