I wouldn't think they'd stop working, but I suppose it would always be possible to get a batch with compromised potency... like dead little guys...
On the site below they say PR Pearls have only 1 billion cfu (colony forming units). One billion is extremely low. Extremely. I've read articles that say if you are going to spend money on probiotics, pick one with at LEAST 15 billion cfu. Their point being that our digestive tract has over a trillion bacteria and ANY probiotic supplement is literally a drop in the bucket.
I would consider trying another brand just to see. Also, there are many brands you can travel with. I think mine says it is fine outside the fridge for a week or 10 days... something like that. They just recommend refrigeration for optimal shelf life. I use Theralac, but I've heard good things about
Udo's, Dr. Michael Murray's and we've discussed VSL#3 here before. I just put my daughter, who is away at college, on Udo's for good measure. Probiotics are supposed to protect/boost the immune system.
Mom to 16 year old son diagnosed in June, 2007.
Omega 3s, digestive enzymes, probiotics, vit. C, calcium w/D3, a good multivitamin and SCD legal yogurt
Started The Maker's Diet in Sept. '07. Gradually learning/using more Specific Carbohydrate Diet (SCD) recipes, too! (cooking challenged)