Glenrothes and Central Fife MP Lindsay Roy is suffering from Parkinson’s disease.
He has announced that he will be working full time in the constituency for the next few weeks but will not be travelling to London to attend the House of Commons while he undergoes treatment.
Mr Roy said: “The effects of the illness are such that I am currently unable to travel to London but plan to return there soon.
“In the meantime I will continue to work full time locally on behalf of constituents.
“It has been an honour and a privilege to represent the people of Glenrothes and central Fife ever since I was elected in 2008 and I can assure them that I will continue to work hard on their behalf until I retire at the general election in May.”
Mr Roy, 65, announced in November 2013 that he would be standing down as an MP at this year’s general election.
He secured the Glenrothes seat for Labour in a by-election following the untimely death of sitting MP John MacDougall.
This success was followed by an overwhelming victory in the 2010 general election, when he more than doubled his majority to more than 16,000.
Mr Roy was rector at Inverkeithing High School for 19 years and had a short spell at the helm of Kirkcaldy High before entering politics. He was awarded the CBE for services to education in Scotland in 2004.
When he announced that he would be standing down as an MP, he reflected on more than four decades in public service and said: “Most people would count themselves fortunate to have one career where they get enormous job satisfaction. I have been privileged to have two.”
Other prominent Fife MPs not seeking re-election in May are Kirkcaldy and Cowdenbeath member Gordon Brown and North East Fife MP Sir Menzies Campbell.