I think that most people here who actually HAVE convinced a doctor to prescribe something will say that often times, it simply isn't the right drug or the right dosage.
I have been prescribed Vermox (mebendazole) twice and it's done nothing for me.
The first time I was prescribed Vermox it was at the pinworm dosage. I had ZERO symptoms of pinworm. So just because that's what a doctor prescribes is kind of meaningless...