Two years ago my dermatologist prescribed tetracyclin (250 mg/day) to treat my mild acne problem. He said that I can use it for a long time, without negative side-effects. It works perfect, but if I stop, it comes back immediately (worse than I had it before). Can I use this drug safely for a lifetime, or should I worry about negative side-effects, e.g. the development of resistant bacteria in my gastro-intestinal tract? And what is the evidence for the connection between the use of antibiotics and breast cancer? Is there a topical alternative that is as effective as systemic tetracyclin?