Reading through the drug insert of quinolones such as Levaquin shows that the incidence of side effects are very rare. That seems very strange, if you look at all those people suffering from quinolone toxicity.

According to Marcia Angell, not only can the incidence of side effects be distorted, but the effectiveness of the drug itself may also be distorted:

"Many drugs that are assumed to be effective are probably little better than placebos, but there is no way to know because negative results are hidden.... Because favorable results were published and unfavorable results buried ... the public and the medical profession believed these drugs were potent.... Clinical trials are also biased through designs for research that are chosen to yield favorable results for sponsors. For example, the sponsor's drug may be compared with another drug administered at a dose so low that the sponsor's drug looks more powerful. Or a drug that is likely to be used by older people will be tested in young people, so that side effects are less likely to emerge. A common form of bias stems from the standard practice of comparing a new drug with a placebo, when the relevant question is how it compares with an existing drug. In short, it is often possible to make clinical trials come out pretty much any way you want, which is why it's so important that investigators be truly disinterested in the outcome of their work.... It is simply no longer possible to believe much of the clinical research that is published, or to rely on the judgment of trusted physicians or authoritative medical guidelines. I take no pleasure in this conclusion, which I reached slowly and reluctantly over my two decades as an editor of theThe New England Journal of Medicine"

A BBC article also agrees that "selective reporting" by drug companies can also occur. This means that even if there are reports of serious side effects, drug companies may want to hide them, and use other favourable reports instead: http://news.bbc.co.uk/2/hi/health/3640488.stm

In the case of quinolones, it can be noted that there is little or no information about the incidence of side effects in the long term. If a medical study on this is actually performed, the medical community's opinions on the safety of quinolones will definitely be changed.