There is very little clinical evidence supporting the actual benefit from probiotic use. I'd really recommend asking your pediatrician their opinion regarding the latest available clinical data on the subject.
Here is an article on WebMD regarding a lawsuit vs. Dannon for making unsubstantiated clinical claims about probiotics in their yogurts: http://www.webmd.com/digestive-disorders/news/20080125/yo...
I sound like a broken record, but most of us have little clinical/scientific training, and while we try to provide the best possible advice based upon our own personal experiences, sometimes it is best to present questions like that to your doctor.
Nothing is completely safe - anyone can have a reaction to anything, so I'm a huge proponent of involvement in involving my doctors in things like that. Then again, I have no idea what caused the cancer I was diagnosed with right after my daughter's birth, so I have a valid fear I never would have otherwise.
Good luck!
Good luck.