In the UK at least, doctors may advise you to take probiotics but do not write you up a prescription for it as it is considered experimental.

I'be personally used acidophilus lactobacillus after an oral yeast infection which I got after taking preventative antibiotics (took pretty much everything - azithromycin, flucloxacillin and ciprofloxacin) for a severe bout of reactive arthritis and it seemed to make a difference. However I was still very messed up for at least 6 months.