side effects of 6MP.......??

Major hair loss is not at all common on 6mp, especially because you'll be on a much lower dose than say an organ transplant patient would be on. Some people lose a bit more hair than normal, or experience dry, thinning, weaker hair, but you're unlikely to go bald or anything.

I never lost hair on 6mp. I wAs always on 50 or 25 mg too.

I'm on 75mg of 6MP for about a year now. No side effects I know of - except after my last blood test I got a letter from my GI saying that my white blood cell count had dropped a bit. He went on to say that is not unusual when taking 6MP but wants me to get another blood test (I just got notice of this the other day) to make sure my count is not continuing to drop.
It's really working for me, so I hope this is just a normal side and nothing that will cause me to go off of it.