Obviously, if after a couple days being on cranberry you don't feel well, then by all means, take
the antibiotic. But when you do, make sure to take
a strong probiotic as well.
You body is full of both good and bad bacteria. Under normal circumstances these two types are well balanced, the good bacteria keeping the bad stuff at bay. But, when you take antibiotics, it not only kills the bad bacteria, but the good as well.