The note from New Trier Supt. Dr. Linda Yonke follows the arrest of a student this week suspected of selling the edibles to other high schoolers.
The case is similar to an incident at Evanston Township High School earlier this month, when a 17-year-old student was charged with possession of cannabis after five students fell sick from eating pot brownies.
School officials are cooperating with the police investigation and say the student faces disciplinary action.
The e-mail urges parents to talk to their kids about the dangers of drug use.