The Junior Switch nightclub, which opened in September last year, hosts events for 13 to 17-year-olds.
For the first time at an event held by the club on Friday night, young people were breathalysed at the door.
A spokesperson said they had been forced to introduce the measure due to the condition of some young people on arrival.
The Monaghan-based nightclub has held a total of seven events since opening.
During its seventh event, held on Friday 12, young people were breathalysed before entering the venue.
This is the first time that the venue has imposed such a measure.
A spokesperson from the Junior Switch nightclub said that it was now a condition of entry for young people attending future events.
"We have a duty of care to the young people who attend our events and we are taking a zero tolerance approach when it comes to the consumption of alcohol."
It is understood that the club enforced the measure after a previous incident in which a bus brought young people to the venue who were unconscious due to alcohol consumption.
Young people gain access to events by purchasing tickets, however since the nightclubs spokesperson said that refunds had been issued prior to Friday night's event.
"We sold tickets and made it clear that those attending the event would be breathalysed. We then issued refunds to those who no longer wanted to attend," the spokesperson said.
"We lost about 40% of our usual turn out, but we don't care about the money. We want to ensure that the young people remain safe.
"Parents are thanking us because they don't want their kids in a situation where other kids are drinking and there may be peer-pressure for them to do the same."
Young people who were tested positive for alcohol consumption were looked after by paramedics from the Red Cross who then contacted their parents.
The spokesperson said that these young people have been told not to return to the venue for future events.
An underage nightclub in Castleblayney, Monaghan, is breathalysing young people before they enter the venue.