50 mg sounds like a lot. The protocol I used recommended 300mcg per day for 120 days, and I now use 150mcg per day a few times a week, not including the amount in my multi.
MSM has been very helpful to many people, but complementary nutrients ensure that it keeps being beneficial. If you take a multi with 75-150mcg per day, that may be enough. Unfortunately, it is all so very individual.