Graham Hume, who made his first international appearances in the summer, has been called up as a replacement
Craig Young has been ruled out of the men's T20 World Cup through injury.
The 32-year-old right-arm seamer has suffered a recurrence of an injury, thought to be a hip problem, during the squad's pre-tournament training camp in Sydney.
Graham Hume, who made his one and only T20I appearance against Afghanistan in Belfast, has been enlisted as his replacement.
He will fly out to join up with the remainder of the Ireland squad, who are due to travel to Melbourne on Sunday (October 9), at the earliest possible opportunity.

Hume represented South Africa at the 2010 Under-19 World Cup (Martin Hunder/Getty Images)
"Unfortunately, whilst out in Sydney for our T20 World Cup prep camp, Craig experienced a recurrence of a chronic issue which we have been managing for quite some time," said head of physiotherapy and medical services at Cricket Ireland Mark Rausa.
"Whilst we thought we were on top of the issue, it sadly flared up once we arrived in Sydney and began training.
"Craig will now return home for an assessment with our medical specialists to plan out his rehab."
Ireland's World Cup campaign begins with a round one clash with Zimbabwe in Hobart on October 17. Heinrich Malan's side warm-up for the tournament against Namibia and Sri Lanka.