Summary: Lacticaseibacillus paracasei DG (L. casei DG) is a specialised probiotic with many unique abilities that determine its high efficacy in many gastrointestinal diseases. These are potentially due to the exopolysaccharide (DG-EPS) produced by this bacterium, thanks to which it has the ability to adhere to gastrointestinal cells to a high degree, which is responsible for very good colonisation of the gastrointestinal tract. Furthermore, DG-EPS determines the significant resistance to external agents and the possibility of L. casei DG interacting with the immune system. The high percentage of gastrointestinal colonisation and its high stability enable this bacterium to interact with the intestinal microbiota, modulating it in such a way as to provide the greatest possible benefit to the human body. This article reviews the literature and the various applications of this probiotic in the context of: irritable bowel syndrome (IBS), syndrome of intestinal microbiota overgrowth (SIBO), symptomatic diverticular disease of the large intestine and even improving the tolerance of the drugs used during Helicobacter pylori eradication. Despite so many different possibilities offered by this specialised probiotic L. casei DG, what seems remarkable is its action in the context of SARS-CoV-2 and, therefore, potentially against post- -COVID irritable bowel syndrome (post-COVID IBS). L. casei DG induces the stimulation of the expression of genes involved in antiviral immunity and, at the same time, prevents the overexpression of pro-inflammatory genes triggered by SARS-CoV-2. Moreover, this bacterium also shows the ability to inhibit SARS-CoV-2 by increasing the immune activity of lactoferrin. This may have potential relevance in patients with post-COVID IBS, in which inflammatory microstates in addition to disorders of the gut microbiome are considered as a cause.