Hair loss is I think a side effect of 6mp. The most serious potential side effect is leuk
openia, or white blood cell suppression. I assume you are having blood drawn regularly to check your white count -- they usually do it every few weeks early in the process and then step down to monthly and then quarterly thereafter. You don't say how long you have been on 6mp, but the side effects tend to show up fairly early. If you are not getting regular and freqient white counts I would definitely call th doc and get in for lab work promptly, as low white cell count can be a dangerous, through reversible, issue.