Jonathan Battle, 10, has severe asthma and complained of problems Monday.
His mother, Danai Battle, took him to Children's Hospital of Pittsburgh, where he was later admitted.
She claims the fifth-grader went without an inhaler for at least an hour because staff at Dilworth Traditional Academy wouldn't let him have it during an attack.
"He was having an asthma attack, told the teacher and she sent him to the nurse; she refused to give him his inhaler," Danai Battle told WPXI.
The school claims her son didn't have a new medical form on file for the current school year, but Danai Battle says the school has known about his severe asthma since the boy was in first grade.
At the time of the attack, Jonathan had an inhaler with him, his mother said.
"The nurse took it off him and said he couldn't take it because there was no form on file for the current school year," Danai Battle said.
Pittsburgh Public Schools sent WPXI a statement saying the nurse can't give medication without that doctor's note and that, "The nurse took the student's pulse and the student's oxygen levels were in good condition."
"No, when I spoke with their nurse she said he was wheezing bad," Danai Battle said.
She said the doctors believed it was bad enough to admit Jonathan for three days.
The district went on to say that once Danai Battle went to the school, she "became verbally aggressive with staff, threatening both the school nurse and principal" and that they filed charges against her and banned her from the school building.
"I went in as any parent would be when your child is sick and distressed. You want answers and you want to know what's going on and you want your child to get medical attention," she said.
A district representative said charges were filed with police.
WPXI checked court records but couldn't find any charges filed related to this incident.