http://www.aafp.org/afp/990215ap/diary.html
In a previous "Diary," we mentioned that aphthous ulcers of the mouth
might be prevented in the majority of patients by avoiding toothpaste
containing the detergent sodium lauryl sulfate (SLS). Now, WLL has come
across another study in the European literature (Acta Odontol Scand
1994;52:257) that showed "a 70 percent reduction in canker sores in
patients who used toothpaste without SLS." A quick trip to the store
will confirm that most brands of toothpaste sold in the United States
contain SLS. However, a couple of brands are free of SLS. It couldn't
hurt for patients to try avoiding SLS. In the past, we have mentioned
other possible preventatives for recurrent aphthous ulcers, such as
taking cimetidine at the first sign of occurrence (December 1995
"Diary") and taking colchicine daily to prevent ulcer formation (January
1995 "Diary").