I have constant bladder infections and have tried all the other drugs that they normally give--my doctor prescribed Levaquin 500 mg and I was on it for three weeks. During this time I have had severe pain in my muscles, I got so I couldn't even BEND my knees and I had to go to the emergency room one morning when I tried to get out of bed and step down on my leg I was in excruciating pain--it felt like one leg was shorter than the other since I could not get it straightened out it felt like the tendons had been shortened. I went to a Urologist and he took me off of the Levaquin--in three days my knee pain is gone! I don't ever want to be on this drug again. I asked my Urologist why it did this and he said it softens the cartilage around the joints.