The socialite - who has had a long history with alcohol and drug addiction - is said to have gone to the Manor clinic in Hampshire for one month.
"Tara has a well-documented history of battling various demons and unfortunately it seems some have returned to haunt her," a source told Grazia.
"She knows when things get bad, the only answer is rehab.
"All those who love her support her and are so pleased she has decided to take this course of action as she has been having a particularly difficult time lately."
The source added: "She's in for a month and we're looking forward to seeing a healthier, happier Tara on the other side."
It has not been confirmed why she has returned to rehab, but the sourced added that it is not as bad as her 'rock bottom' period in 1999, when she sought help for cocaine addiction.
"Tara admits she's slipped up a few times recently, which is why she's sought help. But she's in no way as bad as she was in the past.
"This is not about cocaine, this is just getting her back to full healthy."
The move comes a few weeks after she was spotted entering an off licence in the early hours of the morning looking weary and struggling to keep her eyes open.