Originally Posted by mrsd

Cranberries contain a substance that helps prevent bacteria from sticking to
the wall of the bladder. It does NOT cure an infection already in place.

It is mostly for prevention. There are capsules/tablets of the extract which I think are better. Most of the juices are dilute and full of sugar.

A real bladder infection involves a stabbing sharp pain in the urethra when you void. And that may last a while...or not depending. Frequency and urgency are other signs. You can have a dull ache over your public bone, and if really severe a fever or flu like symptoms.

There are tablets sold in stores in the Feminine hygiene section that contain phenazopyridine. This is an orange dye that numbs the bladder and helps with pain. It does NOT cure infection either, but helps until you can get to a doctor.
You can read about it here:
http://www.azoproducts.com/products/azo_standard