Why did your friend's Dr. say absolutely no MSM? My Dr. advised against it during pregnancy for the same reason he is against any supplements, because they are not regulated by the FDA and so there is no governmental quality control. In other words you don't really know what you are getting. He didn't address the issue of whether the MSM does what it claims to do and whether it is safe (once you get past the quality control issues).
I had done a lot of reading on MSM and understand it to be one of those trace minerals that has been stripped out of our diet through modern agriculture. It has a very low toxicity (somewhere between water and table salt). It has no known drug interactions but that it might have a blood thinning effect so it's probably not a good idea to take it if you are on a blood thinner (such as cumidin). The only known side effect is stomach distress so anyone considering taking it should probably start with a minimal dose. Anyone taking larger doses can spread it over the day. I do know my husband couldn't tolerate it (do to the stomach distress).
MSM really never seemed to do that much for me so I don't really miss it but occasionally I do think about taking it again and sticking with it longer and maybe increasing the dose over time. I get the impression you need it to build up in your system for it to become really effective. I have read some pretty amazing stories about what MSM has done for people with some serious injuries but it might be one of those things that doesn't work for everyone.