The 18-year-old threw a blueberry into his mouth during the session but didn't quite pull off the trick, needing to be helped by onlookers and bandmates.
Styles wrote on Twitter: "Good shoot today!! Long day but some great shots, hope you guys like them x"
The One Direction star added: "But I did throw a blueberry to the back of my mouth an (sic) choked."
A fan later tweeted: "@Harry_Styles I'll give you mouth to mouth if you need it!!! :)"
One Direction are currently on a break from their 'Up All Night' US tour, with the photoshoot on Wednesday their first day back at work.
Watch One Direction's 'What Makes You Beautiful' video: