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Yes, probiotics should help, and yes you should take them always. Well, not forever but everyday for several months. They will definitely help regulate your intestinal function which will in turn help regulate your BM's (bowel movements). They won't fix your IBS or your BM's but they sure will help. If you do a search for probiotics you will find that they are highly recommended if you are on antibiotics, have just had food poisoning or are having (or just had) diarrhea. The probiotics will replenish your "good bacteria" that have just been flushed out.
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