Yeah my drug guide says it can interfere with the effectiveness of the antibiotic. I would go out and buy some monistat too, cause you're pretty much guaranteed a yeast infection too with the antibiotics.
A few years ago, when I was taking phen, I was bitten by a cat and ended up with a severe blood infection. I was put on mega-doses of antibiotics and my doc took me off the phen saying it would interfere with the antibiotics. Didn't say how it would interfere and I wasn't in a state of mind to ask. Hope this helps.
Whereabouts in TN are you? I'm in the Chattanooga area.