The Black Cats have endured a tough opening to the 2012/13 campaign, with three wins from 17 fixtures leaving them precariously perched just a point above the drop zone.
Additions made over the summer were supposed to help Sunderland steer well clear of trouble, but the likes of Adam Johnson and Steven Fletcher have been unable to inspire the North East outfit.
They are, however, proven Premier League performers and O'Neill is confident that further strengthening in the New Year will see his side steadily rise up the Premier League standings.
"We will have to look to strengthen in the second half of the season," he said in the Sunderland Echo.
"You only have to look at the back of the programme to see that we don't have any real numerical strength, as much as anything else.
"You are going to have injuries and suspensions as the season goes on and you have to manage them as best as possible.
"But, yes, we will look at things afresh in January."
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