My son takes LDN, but also does Hyperbaric Oxygen Therapy and SCD, he has been in remission for awhile now, but still watches what he eats very carefully. It seems for us that LDN helped him, but did not get him into full remission, HBOT is definitely what pushed him into full remission - right now he is on a maintenance of HBOT at 2 to 3 times per week.
LDN was prescribed by our GI, he does not prescribe it very often and only at a parents request, but we wanted to try it - with the understanding that if it did nothing we would look at other options.
Just for the record HBOT has 30 years of clinical trials that show it controls inflammation (especially in hard to control areas such as the rectum). Our GI was thrilled that we were using HBOT in conjunction with meds, and has requested regular updates so HE can monitor it for his own information. Unfortunately it does not control symptoms (nausea, diarrhea, etc), our son had very few symptoms beyond his fistula and an ongoing elevated CRP, so HBOT was a good choice for us.