At least two videos posted on social media appear to show Styles wincing in pain and holding his head in his hands after he was struck with an unknown object as he was walking offstage.
Representatives for Styles did not respond to requests for comment.
The apparent incident follows a string of similar ones in which concertgoers have lobbed objects at artists onstage — in some cases causing injuries.
Last month, a 27-year-old New Jersey man was charged with assault after he was accused of throwing a cellphone at pop star Bebe Rexha during a concert in New York City, police said. Rexha was taken to a hospital and was stable, police said.
The suspect, Nicolas Malvagna, said he did it because he thought “it would be funny,” according to a criminal complaint. He pleaded not guilty, said his attorney, Todd Spodek.
Malvagna was released on his own recognizance and subjected to a full temporary order of protection requiring him to stay away from Rexha until at least his next court date, on July 31, the complaint said. He could face up to a year in prison if he is convicted, Douglas Cohen, the press secretary for the Manhattan district attorney’s office, has said.
In an Instagram post after the incident, Rexha appeared with a bruised eyelid and bandages on her eyebrow. "Im good," she captioned it.
Days after Rexha's incident, singer Ava Max said on Twitter that an audience member attacked her during her performance in Los Angeles, writing: "He slapped me so hard that he scratched the inside of my eye. He’s never coming to a show again."
It’s unclear how the man got onstage. A spokesperson for Max’s record label, Atlantic Records, has said there would be no further comment beyond Max’s tweet.
“This is your mom?” Pink asked as she held the bag in a video clip of the incident.
“I don’t know how I feel about this,” she said before she placed the item on the floor and resumed her performance.
And just a few days after that, a fan threw an object onstage at country star Kelsea Ballerini at her show in Boise, Idaho. A fan who recorded a video of the incident said the object was a friendship bracelet.
Representatives for Ballerini didn’t respond to a previous request for comment.
Experts have said they think fans are throwing objects in bids for attention.
Adele warned concertgoers this month not to throw anything at her, according to a clip posted on Instagram.
“Have you noticed how people are like forgetting f---ing show etiquette in America? They’re just throwing s--- onstage. Have you seen that?” she asked the audience as she paced the stage holding a T-shirt gun.
“F---ing dare you,” she said. “Dare you to throw something at me.”
She then shot a T-shirt into the audience and joked: “Stop throwing things at people ... when you can shoot things."