The Irish boy band were due to perform in Bangkok, Thailand, on Thursday but had to go on stage a man down.
Duffy, 44, was taken to hospital “on the advice of the local medical team”, a statement said.
A tweet from the band’s official Twitter account said: “Our brother will be back on his feet as soon as possible and we thank you for all your wonderful support in the meantime.”
Boyzone, also consisting of Ronan Keating, Mikey Graham and Shane Lynch, are on a farewell tour to mark their 25th anniversary.
They are next scheduled to perform in Perth, Australia, on March 30. It is unclear if Duffy will be performing.
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