Hafedh Caid Essebsi the president's son said that Essebsi was hospitalized on Wednesday after he suffered the effects of last month's crisis, confirming an earlier report on local radio.
Essebsi, a major player in the country's transition to democracy since 2011, had been hospitalized late last month and spent a week in hospital after suffering a "severe health crisis."
But the president has only appeared twice since leaving the hospital on July 1.
Essebsi has been a prominent figure in Tunisia since the overthrow of veteran autocrat Zine El-Abidine Ben Ali in 2011, which was followed by uprisings against authoritarian leaders across the Middle East, including in nearby Libya and Egypt.
Parliamentary elections are expected to be held on Oct. 6 with a presidential vote following on Nov. 17. They will be the third set of polls in which Tunisians can vote freely following the 2011 revolution.