"He is doing well under the circumstances," said Michael Offer, adding that Schäuble was "conscious" and "understands what is being said to him" after taking new medication for the first time, according to his ministry.
Schäuble was replaced at the emergency euro talks by Interior Minister Thomas de Maiziere, who travelled to Brussels at short notice.
A key member of Chancellor Angela Merkel's cabinet, Schäuble has suffered ill health for the past several months, with a wound from an operation failing to heal properly. The 67-year-old has been confined to a wheelchair after a 1990 attack by a mentally disturbed man who fired three shots at him.
His hospitalisation came shortly before Merkel's Christian Democrats suffered a harsh defeat in a key state election in North Rhine-Westphalia.
The loss cost the centre-right coalition in Berlin its majority in the upper house amid voter anger over the bailout for debt-stricken Greece.