Had IBS all adult life (and lots of otehr stuff) ... just joined to add this.
Been taking Activia since about Jan. Normally I avoided dairy but wanted to add it and hoped this would help. Probably has. Read recently that if you take probiots you need to keep taking them. I presume that because the makeup of our systems determines what growas there naturally, and in the case of pathology, like IBS, we can presume that "something's wrong" ... with "the environment" ... and not likely to change. So if you put something down there that helps, it's not going to tend to stay there (or you would likely not have such a problem in the first place). All this and what's below comes after fourty years of applying my scientific mind to my totally contrary body.
As always there would be a variety of reactions (to using Activia or anything else), from good to bad, because "IBS" doesn't seem to be "one thing" ... plus there are other factors that can affect outcomes ... lactose intolerance (some here), sugar intolerance (much here) ... PLUS there is the dietary factor ... we each have different diets ... PLUS there is the fact that calcium (metals in general) tend to be constipating ... on and on.
It also seems to reason that once you start, you likely need less/day to maintain ... try 1/3 of 4 oz carton per day instead of all. Works for me and saves $$ too (and less calcium, lactose, sugar, etc).
SO ... try it. If it helps keep taking it. If not, don't. The variables are not in the product ... they are in the people.
My MIRACLE aid (#1) for IBS came when Miralax came out (PEG 3350). It is not a "laxative", really ... it's a water soluable plastic that is not absorbed by the body, but which itself hangs onto water. My system tends to completely dessicate (dry out) "overnight (sleep)" and especially the contents of the gut. I have been known to eliminate a gallon of liquid while sleeping ... or rather trying (but missing half of it getting up). This was partially caused by iron deficiency apparently (see later).
Miralax alone was a help when constipated, but with variable results, but MUCH better when I tried mixing HALF a dose (about 8 gm) in 10 oz. water with 1/2 teaspoonful of sugarless, orange flavored "Metamucil" and stirring for 5 minutes before drinking (once a day as needed, or twice in "bad times"). REALLY gives me some control over symptoms reliably for first time. Try this for IBS control of especially constipation and that HORRIBLE boating. Miralax is now OTC, but generic prescription is 1/2 the cost (Glycolax, etc.) In 3 years the generics will be OTC too. You may also want to try 1/3 dose in "wet" oatmeal (I have to over-wet my food) made 3:1 water/oats.
I tried this because the old standby Metamucil always made me much worse because my body just drags all the water out of it and turns it to concrete. The Miralax mixed with it, even at those low doses, seems to combat this, and the oatmeal works that way too (that is, my body needs soluable and insoluable fiber that it CAN'T dry out ... for me a nearly impossible order).
Finally, for GERD (meeee tooooooo!). This is NOT a panacea, and may apply to only a few, but I discovered last year that my GERD, although mechanical (sphincter weak), was ACUTE principally due to a severe and worsening iron deficiency that only showed as "low normal" on blood tests. Nearly killed me. One meal (nothing but BBQ and a beer) tipped me off (expected it to kill me ... felt better than for years).
Anyway, as soon as I started 1 RDA (about 18 mg, I think) per day iron supplement (whidh doesn't help IBS much but some, contrary to expectations of worsening intestinal problems with iron supplementation) my GERD got dramatically better.
I reason as follows ... you see, the principle reason for highly acid stomach is to get metals (form foods) the body needs, apparently principally iron. Acid + metal = "salts" of metals that the body can absorb. We tend to phase out red meat to try to soothe our IBS ... and at the advice of "everyone" as we age. If one is a poor iron absorber AND has some GERD AND takes antacids AND cuts down on red meats, ALL this may make the stomach put out more acid to try to grab onto every lonely iron molecule that passes it by. More antacids. Vicious cycle.
Iron supplementation for me really turned off the acid machine! I still "have GERD" ... but it doesn't bother me now because the material is hardly acid at all comparatively. Gone from a constant, everyday problem to a few minor episodes a year.
Accompany 18 mg of iron with 250 mg of vitamin C, or for best effect a glass of beer or wine (and food). "C" and alcohol, especially latter, help iron absorbtion ... and is likely why "drunks" are so red often (and is part of what kills them ... too much iron absorbtion)
You should probably check with doc on this. Over supplementation of iron is DEADLY. But if you notice that when you eat red meat you often have less, not more, GERD problem (against expectations) might be worth it. Try some red meat and a beer or wine alone and "sleep on it" (eliminate all theother variables). If it cures you instead of kills you, you may be onto something. (Beer had gotten to be impossible for me ... but not with red meat alone.)
I will guess your doc has never heard of this "theory" before ... neither had I (but I think he'll see how it fits with the science and medicine). I'm just telling you what was/is true for me. In me, the effect is absolutely clear and undeniable. When I forget iron for a few days ... well, you know.
Please, though, you should determine if you need iron first ... but know that you may, even if you test "low normal". If you have (GERD plus) other symptoms, like paleness (mine was most noticeable on heavily sun-dmamged left arm), shortness of breath (yet able to breathe fine), skin problems, fatigue, worsening episodes of inability to keep your thoughts going, etc. (for me it was literally everything), look into it. One peculiar but apparently reliable indicator of possible iron deficiency is the loss of the outer 1/3 of your eyebrows, strangely, and a mystery I wondered about for years.
Good luck to all.