Former Prime Minister Manmohan Singh was on Sunday night admitted to AIIMS after he complained of chest pain and uneasiness.
Manmohan Singh developed a reaction to the new medication and his health condition being investigated further, hospital sources told PTI, on Monday.
The 87-year-old economist-turned-politician has been admitted to the cardio-thoracic ward of the premier healthcare institute and not the intensive care unit.
"He had developed mild fever and complained of uneasiness. He is under the observation of doctors," a Congress functionary told DH.
Congress sources said Singh was doing fine and all his medical parameters were normal.
Singh had undergone bypass surgeries in 1990 and 2009 and a stenting procedure in 2004.
A man of few words and calm demeanour, Singh was one of the longest-serving prime ministers having served two consecutive five-year terms, a feat achieved only by Jawaharlal Nehru and Indira Gandhi.
Deccan Herald is on WhatsApp Channels| Join now for Breaking News & Editor's Picks