It happened around 11:00 a.m. at the Rudolph Blankenburg Elementary School in the 4600 block of Girard Avenue.
Philadelphia School District Spokesperson Fernando Gallard says a staff member at the school noticed a group of second graders - all approximately 7 years old - with a small container containing birth control pills.
Nine students, two boys and seven girls, ingested the pills, and as many as three others tasted the pills but did not ingest them.
None of the children ever became sick, Gallard said.
Officials then contacted the CDC, Children's Hospital of Philadelphia, and local law enforcement, and according to Gallard, they all advised the district that no additional medical attention was required.
Based on those recommendations, none of the children were transported or taken to the hospital.
The district says the school will talk to students about the dangers of medications, and a letter will be sent home to parents describing the incident.
An investigation into this incident continues.