Definitely trial and error. What works well for one person doesn't work well for someone else.For diarrhe usually the following are things people tend to try and find works.Antidiarrheals. Mostly Imodium and Lomotil. Lomotil has some addiction potential so usually can't be taken long term. Imodium doesn't have the same risk, but has a similar mechanism.Antispasmodics. Relieves cramps and spasms may calm things down so they don't move so fast (Levsin, Bentyl, et al).Anti-anxiety meds. Esp for those where nerves trigger D. May be combined with Antispasmodics in some medications.Antidepressants. Serotonin is a big player in the gut nerves. Tricyclics, SSRI's and Remeron (which acts on the receptor Lotronex does).Bile-binding agents. Questran/Colestid. Can be quite constipating in some non-IBSers and can for some people do wonders for diarrhea.Supplements. Generally Calcium tends to be constipating and helps some people. Some people try various herbs. Peppermint is an antispasmodic and used quite a bit.As for me, see the link in my sig.K.