Dundee city councillor Fraser Macpherson has been rushed into hospital, suffering from pneumonia.
The West End Lib Dem councillor was admitted to the intensive care unit at Ninewells Hospital around midnight on Saturday after suffering from severe chest pains.
He was given emergency treatment and placed in an oxygen tent and given 100% oxygen, his wife Janet said.
She said Mr Macpherson was feeling “a bit better” but would be out of action for a lengthy period.
He had been taken seriously ill earlier on Saturday and they had visited NHS 24 premises at Wallacetown Health Centre, his wife said.
While there he suffered severe chest pains and worried staff called an ambulance to take him to hospital.
Mrs Macpherson said: “They were very good and Fraser wants to thank them for the way they reacted.
“He says he’s been very well looked after and says NHS 24 staff and the staff at the ICU have been very professional.
“He couldn’t have been treated any better.”
Mrs Macpherson added: “He couldn’t really speak this morning but he’s now feeling a bit better than he was.
“He is in the high-dependency unit and is being given 100% oxygen in a tent.
We can’t fault the care he has been shown.
“We’re just back from Australia and we think he maybe contracted pneumonia out there.
“He’s had a cough for a while and I’ve been telling him to get it checked out.”
She said doctors had also been concerned about a possible pulmonary embolism after the long-haul flight and that had also been checked out.
She added: “Typically, although he’s in intensive care and is very tired, he’s been busy sorting things out from his bed.
“He’s been trying to clear some things with the council as it’ll be a long road. He’s starting to recover but he’ll be out of action for a while.”
Mr Macpherson is recognised as one of the most enthusiastic councillors among his fellow peers.
Right up to his illness, he had been dealing with both his constituency business and with his counter-proposals for Thursday’s council budget, posting on his blog about his alternative savings ideas.
Administration leader Councillor Ken Guild said: “I’m very sorry to hear about this and I would like to wish him a full and speedy recovery.”
Fellow ward councillor Labour member Richard McCready said: “I’m very sad to hear that Fraser is unwell. Obviously we can be political rivals but we work together for the people of the West End, and I wish him the very best and a full and quick recovery.”