Tamzin Outhwaite needed to be checked over by medics after banging her head on ice during filming of Freeze the Fear with Wim Hof - with such a scene set to air this week.
The latest episode of the BBC endurance series saw the celebrity participants tasked with swimming under "thick ice," with air holes placed at 2 metres and 4 metres apart.
Some of the celebrities have been shown attempting the challenging already - with viewers set to see EastEnders alum Tamzin, 51, take it on during the next episode.
And a first-look clip has teased that it doesn't go smoothly for the actor, with her seen banging her head as she comes up for air - leading to medical attention shortly after.
The clip, shared by the Daily Mail, shows Tamzin plunging into the water wearing a swimsuit and a pair of goggles - as hosts Holly Willoughby, 41, and Lee Mack, 53, watch on.
The scene shows the mother-of-two pulling herself along a piece of rope whilst under the ice as she approaches the next air hole, which is 2 metres from where she jumped in.
She however is seen bumping her head against the ice as she's about to come up for air, sparking concern among the hosts and the other celebrities who are yet to take part.
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Holly - whose husband Dan Baldwin, 47, is the cousin of Tamzin - is heard expressing concern, saying: "She hit her head, she hit her head!" Co-host Lee asks if she's okay.
Tamzin is seen emerging from the water visibly shaken and holding her head, saying: "Banged my head. I'm getting out." She's helped out of the ice by extreme athlete Wim Hof, 63.
Lee remarks that she suffered a "nasty whack" to the head, with Chelcee Grimes, 30, and Stephen Manderson, 38, - better known as Professor Green - watching in shock.
Holly asks if Tamzin needs to see a medic and comforts her, seen hugging her cousin-in-law following the incident. "She has got a bump on her head," the co-host observes.
Tamzin is heard suggesting that she "might need to sit down," with Holly assuring that they will get her "checked out" to make sure that everything is okay after the injury.
The teaser clip ends with Tamzin being led away from the ice by the medical team on the show, with Holly heard telling the participant: "They're gonna look after you."
The Mirror approached the BBC for comment.
Freeze the Fear with Wim Hof concludes tomorrow night with its sixth episode, which will air from 9pm on BBC One and BBC iPlayer. Catch-up on previous episodes now.
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