The students of class 9th of the Sanketh Vidhyalaya in Manpada area of Thane city, complained of nausea, vomiting and giddiness immediately after eating chocolates distributed to them in the classroom for the birthday celebration of a female classmate, police said.
The 20 students, including eight girls, were rushed to the nearby Titan hospital for treatment, police said.
After treatment, most of them were allowed to go home while five were kept under observation, hospital sources said.
Meanwhile, the chocolate samples have been seized by the FDA and sent for analysis, police said.
A school official said they were not aware about the birthday celebration. However, the school has henceforth banned such celebrations.
Instead, the students have been asked to distribute writing material or books on birthdays, he added.