James Collins' hamstring injury suffered in a 3-0 loss at Sunderland means Guy Demel, James Tomkins and Winston Reid are the only front-line defenders available for Wednesday's FA Cup third-round replay at Manchester United.
It means Allardyce could change his system at Old Trafford, rather than promote youngsters, with crucial games coming thick and fast this month. "I've got to strengthen our defensive areas," Allardyce said. "It's less than the bare bones at the moment. It gives me great difficulty going to Old Trafford tomorrow."
The predicament makes life difficult in the transfer window, with Allardyce keen to add to his defensive options. "What you don't want to be is like what we are, which is a little desperate because of our injury problems," he added.
"At this stage of the season it's 'Call My Bluff'. You say no, they say no and then you sit and wait and bite your fingernails and hope they change their mind and say yes. That's why so much happens in the last week of the January transfer window. It's more expensive at this stage of January than it is at the latter stage of January."
Allardyce dismissed reports linking fit-again midfielder Mohamed Diame with Arsenal and insisted the Hammers have not made a further bid for Blackburn's Martin Olsson.
"We've had no bid or official bid at all from Arsenal for Mo Diame and I can't see where he's going to fit in," Allardyce said. "I can't see who he's going to replace. There wouldn't be any point in him going unless he's playing, would there?"
With Barclays Premier League matches against QPR and at Arsenal in the next week and a total of four matches remaining in January, Allardyce is aware rotation is required, but he is hamstrung over his defence. The schedule makes recruitment a challenge too as any new arrival must be ready to play immediately.
"The one area I should rest is the defenders, but I can't," said Allardyce, who is still deliberating how best to integrate new signing Wellington Paulista into the side. "If I don't rest the defenders and they get injured, I'm in bigger trouble against QPR on Saturday.
"Until we get those injuries back we're in a delicate position in terms of the amount of games we've got as well. It's about getting players in who have the experience and the talent and hopefully the determination to get through that period with more victories."