A US high school has suspended four students who needed a boost of caffeine. After eating mint-flavored caffeine pills, the students were suspected of taking illegal drugs, sent home, and banned from homecoming festivities.

After eating the mints during the lunch break at the Pekin Community High School in Illinois, the four boys were sent home while school officials had the mints tested for illegal substances. After determining they simply contained high doses of caffeine, the school continued to enforce the boys’ suspension.

The school “approaches consumption of mood-altering substances very seriously given both the health risks at issue and a mission to keep both illegal and legal drugs and substances out of school,” officials wrote in a statement.