The ad, created by Brand New School, will run with 'Harry Potter and the Deathly Hallows – Part 2' nationwide from Friday. The 30-second spot, entitled "life. live it", aims to raise first-aid awareness among 11- to 16-year-olds.
The split-screen spot depicts two outcomes for a young girl who gets drunk at a party. In the first depiction, the girl lies unconscious while her friends do nothing. In the second version, the girl's life is saved as her friends use simple first-aid techniques.
The ad was directed by Robert Bisi, with editing and production by Brand New School. It will run exclusively in Digital Cinema Media's Odeon cinemas.
Fiona Smith, head of marketing and brand development at the British Red Cross, said: "The campaign shows how first aid can be the difference between life and death, and offers teens the chance to learn life-saving skills.
"The 11 to 16 age group is a particular target for us and as so many of them will be going to see Harry Potter over the next few weeks, we thought it was the perfect opportunity."
Danny Rosenbloom, managing director at Brand New School, said: "The concept is strictly no-nonsense, brave really, and we're so pleased the British Red Cross loved it as much as we did."