I had a lung infection for 7 months when I was living in Australia. It was hurting my lungs significantly. I tried a number of antibiotics in Australia but they didn't seem to help. I came back to the U.S. and my doctor prescribed 750mg of Levaquin for two days followed by 10 days of Levaquin 500mg. At the end of the 12th day my lungs were clear as a bell and I could take full breaths without feeling pressure or pain. It was amazing. I did notice that my heels were hurting while I was taking Levaquin and then for about 8-9 days subsequent. I had trouble walking down steep stairs without going sideways. However now I am fine. On balance, I would say that it was more than worth the ankle problem.