"We have discussed this internally and are looking at the market," Dortmund chief executive Hans-Joachim Watzke told Die Welt newspaper.
"I do not want to rule out that we will be active in the transfer market after Blaszczykowski's injury."
With Dortmund facing Zenit St Petersburg in the Champions League last 16 next month, last season's runners-up need to boost their resources in midfield.
"We know the transfer options in the window are rather limited," Dortmund sports director Michael Zorc told reporters. "Which club would want to part with a good player in mid-season?"
The 2011 and 2012 champions have struggled in the Bundesliga and are 14 points behind leaders Bayern Munich in third place.
Dortmund will be 17 points behind if Bayern beat VfB Stuttgart in a rescheduled game on Wednesday.
Coach Juergen Klopp has had to reshuffle his defence and midfield repeatedly this season, throwing youngsters Erik Durm, Marian Sarr and Jonas Hofmann in at the deep end.
Klopp now has only 21-year-old Hofmann and Pierre-Emerick Aubameyang as options on the right wing with the team busy in three competitions.
Dortmund, who will lose striker Robert Lewandowski to Bayern next season, have picked up two points in four league games and only one point from their last four home matches in the Bundesliga.
The only publicly-traded club in Germany posted a record turnover of 305 million euros (£250 million) in 2012/13, less than a decade after being on the brink of bankruptcy.
Among the players Dortmund would love to re-sign is Manchester United's Shinji Kagawa.
The Japan forward played for them from 2010-12, winning two league titles and one German Cup.
Kagawa has failed to earn a regular starting spot at United and will be pushed further down the pecking order after the signing of Juan Mata from Chelsea at the weekend.
"We know the qualities of Shinji and his immense contribution in the years he played for us. But he is currently a Manchester United player," said Zorc.
- Sports & Recreation
- Mats Hummels
- Michael Zorc
- Neven Subotic
- Bayern Munich