Deb brings up a good point.

The probiotics found in stores typically are not so great.
If you buy locally, only purchase those that are kept in the refrigerator.

The very expensive ones found on the net are typically packaged under nitrogen to keep fresh. The premier ones come in GLASS containers too.

Probiotics are really hot items now. Doctors have come around to understanding their usefulness. But the good ones really cost alot of money. ($40 and up for a month's supply)

There is one caution however. If a person is immuno-compromised, they can be dangerous. Also if one is acutely ill, I'd refrain. A new study just came out using probiotics in patients with acute pancreatitis, and some deaths occurred. A surprise to all. (not in the placebo group)

http://cme.medscape.com/viewarticle/570319
If you cannot view this article, register --it is free.
Also I recall years ago in another forum, an HIV patient posted that he knew a man who died from probiotics. It appears that some products are contaminated with fungal organisms..this is a consequence of how they are manufactured. These contaminants are possibly virulent to people with depressed immune systems.

based on my son's reactions to probiotics since his autoimmune Crohn's dx i would so agree with that.

He used to eat yoghurt and drink kefir regularly but if he has them now he has bad GIT reaction.

This is scary in itself. I know I have tried them two different times, and they made me feel too sick to continue.