There has not yet been a dosage amount set for the use of MSM because it is considered safe to use. The common intake is about 1,000 mg to 3,000 mg of MSM daily (MSM & Hair Growth). I personally would recommend not starting with too high of a dosage. Yeah you may be very eager to try out MSM but it may be in your best interest to actually start of low just so that you can get your body accustomed to the elevated levels of sulfur.
A trial was conducted by Ronald M. Lawrence, M.D., Ph.D. The trial showed that 100% of those subjects who where on Lignisul MSM had an increase in hair growth compared to those who where given the placebo. And 50% of the subjects given Lignisul MSM, compared to the control group, had an increase in nail length and nail thickness growth. Dr. Lawrence concluded that "oral supplementation with Lignisul MSM is a valuable addition to hair and nail growth. Hair and nail health was significantly improved in a short term of six weeks. If the trials were continued for eight to sixteen weeks, the results would have been even better for those on Lignisul" (Lindberg).
Because of these reasons and many more I have decided that I want to add MSM to the regimen. Supplements will be very essential for my healthy hair growth, especially since I'm in college and never seem to find time to actually eat food. Adding vitamins and other supplements will help in not only my hair but most importantly my nutrition and body. The only downside is that I hate taking pills on a regular basis, so hopefully I won't forgot to take them.