This is the third time he is being treated in a matter of weeks.
The 92-year-old president was taken to a military hospital on Wednesday.
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.
The presidency was not immediately available for an official comment.
Since his discharge on July 1, Essebsi has only appeared twice in public.
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 October 6 with a presidential vote following on November 17. They will be the third set of polls in which Tunisians can vote freely following the 2011 revolution.