Ravel Morrison has returned to parent club West Ham from Cardiff City on compassionate leave.
Brighton boss Sami Hyypia is weighing up a move for former France captain Alou Diarra.
Manager Peter Taylor has moved to bring in Hewitt with current right-back Michael Harriman away on international duty with the Republic of Ireland Under-21 squad.
Highly-regarded Hewitt, 19, signed for Ipswich from Macclesfield in the summer of 2012 but has not yet nailed down a regular first-team place at Portman Road, making 12 appearances.
He will now look to add to his experience at Priestfield, starting with Saturday's League One trip to Sheffield United.