Northern Ireland's Democratic Unionist Party (DUP) leader is expected to be discharged from hospital tonight.
Peter Robinson, 66, was admitted to Belfast's Royal Victoria Hospital on Saturday after suffering an adverse reaction to prescribed medication.
A spokesman for the RVH said doctors were "proposing to discharge him this evening".
In May, Mr Robinson spent four nights at the RVH after suffering a suspected heart attack and had three stents fitted to help the flow of blood.
At the time, he blamed his illness on a diet of fast food and lack of exercise rather than the stress of his job.
DUP MP Jeffrey Donaldson said he believed his party leader would be fit to attend cross party talks aimed at saving the powersharing institutions at Stormont on Monday.
Mr Robinson has endured a punishing schedule since the devolved Assembly was plunged into crisis following the murder of a man by Provisional IRA members last month.
He temporarily stood aside as First Minister and pulled all but one of his ministers out of the five party Executive as the crisis deepened.
In a statement, the DUP said his overnight hospital admission had been a precaution.
"Mr Robinson had a reaction to some medication and was admitted as a precautionary measure.
"He is doing well and will be discharged soon."
Political rivals have expressed concern and wished him a speedy recovery.
Sinn Fein's Deputy First Minister Martin McGuinness said on Twitter: "Concerned that Peter Robinson admitted to hospital but pleased that he is comfortable & doing well. Wishing him the best for recovery."
Ulster Unionist Party (UUP) leader Mike Nesbitt said: "It is concerning to hear that Peter has been admitted to hospital. I hope that it is not serious and that he will be back on his feet again as soon as possible."
The political institutions have been rocked following a police assessment that Provisional IRA members were involved in the shooting of Kevin McGuigan in August in a suspected revenge attack for the murder of former PIRA commander Gerard "Jock" Davison three months earlier.
Round table negotiations aimed at resolving the difficulties were scheduled to start last week but were stalled after unionists demanded UK Government action on paramilitaries before the talks could begin.
On Friday, Northern Ireland Secretary Theresa Villiers' proposal for an independent examination of the role, structures and purpose of paramilitaries was accepted by the DUP and UUP who committed to being at the negotiating table.
Also on the agenda at Stormont House will be the full implementation of the Stormont House Agreement which aimed to tackle legacy issues relating to Northern Ireland's Troubles, the budget and controversial welfare reforms.