Nine patients on Ward 10 at the hospital showed flu-like symptoms on Sunday and Monday, and the 20 remaining patients on the ward were given Tamiflu in an effort to prevent it spreading further.
That appears to have worked, with no new cases having been reported.
The influenza was restricted to just one ward at the hospital, and it was closed to new patients until it was controlled.
A spokesperson for South Tyneside NHS Foundation Trust said: “The ward was reopened on Tuesday and no further new cases were reported.”
The breakout of flu came just weeks after a similar outbreak of norovirus at the hospital.
At its peak, 18 patients and 15 members of staff contracted norovirus.