I have received several hundred e-mails, most of which relate terrible, often catastrophic reactions to Levaquin, and some to Cipro. These reactions are slow to pass, leaving some people disabled for months or years. It is an awful problem... Unfortunately, many doctors do not know that fluoroquinolones can cause such severe, long-lasting reactions. When a reaction occurs, some doctors deny that it could have been caused by the drug. Doctors order a battery of tests to seek other causes, but the tests usually show nothing.