She was hospitalized at the Otamendi Clinic late Sunday for monitoring and treatment of the infection, according to the presidential medical unit.
The statement, signed by doctors Marcelo Ballesteros and Ricardo Solla, read that Fernandez, 61, "developed an infectious fever Sunday afternoon due to which it was decided to admit her to the Otamendi Clinic for tests and treament."
Two weeks ago the president had to rest for two days on account of laryngitis.
In July, Fernandez called off a trip to Paraguay due to "acute pharyngolaryngitis", a throat infection which also prevented her from attending the World Cup football final between Argentina and Germany in Rio de Janeiro.
A year ago, the president underwent surgery for a cranial hematoma that kept her from her official duties for a month.
In 2012, the president's thyroid gland was removed following a cancer diagnosis that turned out to be in error.