The four pupils from Garstang Community Academy were 'sanctioned' last week after an incident involving alcohol.
One pupil brought alcohol to school and three others were sanctioned following a school investigation into their involvement.
Confirming the incident, headteacher Alisdair Ashcroft said: "Last week, there was an incident at GCA involving a student bringing alcohol into school which was very quickly dealt with.
"As soon as the alcohol was discovered we contacted parents and sent three students home as a precaution, and following an investigation the students received sanctions for their involvement."
The head, who has been a teacher for 25 years, said it would be 'inappropriate' to comment on the nature of the sanctions.
"It was regarded very seriously, and sanctions were appropriate to the misdemeanours," he said.
"Parents were informed as soon as the issue was identified and understand the approach the school has taken."
The school did not confirm whether any of the alcohol had been consumed by the pupils or if it was consumed on site.
Since 2017, the school has been part of the Fylde Coast Academy Trust and was rated 'good' by schools watchdog Ofsted after its last full inspection.
GCA previously banned pupils from drinking water in class with Mr Ashcroft calling drinks bottles 'a distraction'.
Department for Education figures show that nationally, permanent and temporary school drug and alcohol exclusions rose year on year since 2014.
Latest figures for the 2018-2019 show that 688 pupils were excluded permanently for drug and alcohol related incidents, 45 more than in 2017-2018.
Temporary, or fixed period, exclusions for drug and alcohol were significantly higher in 2018-2019, standing at more than 11,000.
The most common reason for permanent and fixed period exclusions for 2018-2019 was persistent disruptive behaviour by pupils.
Lancashire County Council invests more than £1 million annually on drug and addiction services for young people which is delivered by national charity 'We are With You'.
More information on the support provided by We are With You can be found at its website here.