Probiotics can cause GI disturbances as you are initially introducing good bacteria into your system, in an effort to support gut balance. While the "bad" bacteria is leaving, bloating, gas and other GI disturbances can be temporarily experienced. Lactobacillus reuteri is an important and powerful microbe that is, in a sense, “cleaning” your gut environment. It is totally normal to experience some gas and possible diarrhea at the beginning as it introduces changes into the intestinal microbiome. This is good news and will typically dissipate once your microbiome is used to the supplementation.