Three teenage girls are facing criminal charges in the United States after knowingly exposing a classmate with a severe pineapple allergy to the fruit, police say.

A 14-year-old is accused of rubbing pineapple on her own hand and then high-fiving the girl with the allergy during a lunch period at Butler Intermediate High School in Butler, Pennsylvania, on December 13.

The victim, also 14, was transported to Butler Memorial Hospital, where she was treated and released, The Associated Press reported.

NZ GARDENER A 14-year-old is accused of rubbing pineapple on her own hand and then high-fiving the girl with the allergy during a lunch break.

The girl's allergy was well known, police said, and pineapple was typically not served during that lunch period.

The 14-year-old suspect is being charged in juvenile court with felony aggravated assault and criminal conspiracy, among other offences, according to the AP.

Butler County prosecutors suggested aggravated assault charges, saying the girls knew about the allergy.

Matthew Pearson, a lieutenant with the Butler Township Police Department, explained to the television station KDKA the severity of the victim's allergy. "She could go into anaphylactic shock and, if not properly and quickly treated, could die."

He added: "The main defendant put some on her hand. They conjured up a game, a plan to expose her through high-fiving her."

The two other girls, who are 13 and 14, are charged with criminal conspiracy, among other offences, according to KDKA.

The Butler Area School District said in a statement to KDKA on Thursday afternoon (Friday NZ time) that it would not comment on the specific incident.

"However, it is our expectation that our students respect themselves and others. When that does not occur, the district will take appropriate disciplinary action and, if appropriate, contact law enforcement," the statement said.

Dr Allison Freeman, an allergist-immunologist with Allegheny Health Network, told KDKA that it's becoming more common for bullies to use food allergies against victims.

"It's definitely something schools need to be talking about," she said. "It's no joke, and putting a little bit of peanut butter on the keyboard to hurt somebody is a potentially deadly thing."