LF is very safe. Ive been doing it for about 7 years and have never heard of one person getting a stone stuck. The Drs are the ones saying not to flush so they dont lose more patients to butcher. If your really worried about a stone getting stuck you can drink apple juice for a week/few days before flush to help shrink the stones. You can also use malic acid to shrink stones as well. The information should be at the top of page somewhere.