Pupils drank ethanol which had been stolen from a science lesson at a Northamptonshire school.
The students took the bottle from Latimer Arts College, Barton Seagrave, Kettering, it emerged on Thursday.
Headteacher Siobhan Hearne said staff realised after the lesson a bottle was missing and sought medical advice when it emerged the chemical had been drunk.
None of the pupils is thought to have suffered any side effects but one was taken to hospital as a precaution.
Ms Hearne said: "We became aware of this (the missing bottle) immediately as our safety controls ensure that all equipment used in experiments is counted out before the start of lessons and counted back in straight away after lessons end.
"All the students involved in the incident are back at school.
"An investigation has taken place to establish the full facts so we can take appropriate disciplinary action.
"Alongside that, we will be using this incident to highlight to our students the potential consequences and dangers of misusing substances in any form."
Northamptonshire County Council said its science advisers would alert other colleges about the potential for such incidents.
Ethanol is a strong form of alcohol which is used in schools for a variety of experiments.