The accident happened in Deepdale Road, at the junction with Crossdale Road, when a Volkswagen Polo and Vauxhall Astra crashed just after 6pm tonight.
Police cordoned off the road while firefighters cut away the roof of one of the cars, which had come to rest on an grassy embankment, to free the trapped woman.
She was taken to hospital, where her injuries are not thought to be life-threatening, police said.
No one else is thought to have been injured in the crash.
The busy main road was shut to traffic until just after 8pm, and recovery vehicles were called to take the cars away.
Nearby resident Brian Hindley, aged 74, said: “I saw the firefighters cutting away the roof.
“I was quite shocked when I saw the accident, it was unbelievable — if she came out of that then she is very lucky.
“The road was blocked off.”