The HSE says the suspension of walk-in Covid testing centres could last for the next two weeks.
It's aiming to reduce queues at sites after demand rose by more than a third in the last 48 hours.
The increase is being driven by under 14s coming forward following the return of schools.
Niamh O'Beirne, the HSE's national lead for testing and tracing, says people will need to go online and book a test instead.
People can also be referred for a test if they're a close contact or are sent for a test by their GP.
"This will enable everyone to get an appointment but also for people to manage the queues on site", she says.