The SMA Stay Down formula is thickened with natural corn starch. The Aptamil AR formula is thickened (thickens in the tummy more than in the bottle) with carob flour. IF your kiddo can digest it, it's great for reflux as it really is much harder to bring up. however, my kiddo was always having constipation issues and the carob definitely did not agree with him. He got very constipated and needed to be put on laxatives. My kiddo still struggles with starches in general. He has cow milk protein intolerance though so the only thing that really helped was putting him on Aptamil Pepti formula. I guess you only know if you try though, that's the downside to reflux! Has cmpi been ruled out in your case? There is also Aptamil Omneo Comfort which has natural starches (so it is slightly thicker than the standard) but also has partially broken down cow milk protein which makes it an easier-to-digest formula. It says on the package that it's for babies with constipation issues. I used this for Nathan's reflux because it had a mix of both (though the starches don't thicken exactly the same way as the carob) and this worked great but he needed the protein to be more broken down eventually. My kiddo cannot digest the cow milk protein which is why he was always constipated. He was also very windy and had bad reflux issues. Just mentioning it in case, as too many doctors are overlooking this.