VSL#3 is an ultra-high-potency probiotic medical food intended for the dietary management of irritable bowel syndrome (IBS), ulcerative colitis (UC), and an ileal pouch (pouchitis).

VSL#3 should be stored under refrigeration at 36–46°F (2–8°C) to preserve potency. It can remain at room temperature for up to 2 weeks without reducing effectiveness.

Medical foods are formulated for the dietary management of diseases or conditions with distinctive nutritional needs that cannot be met by diet alone. Unlike dietary supplements, medical foods are intended for use under a healthcare provider's supervision.

In a 2021 clinical study, VSL#3 demonstrated dietary management outcomes in people with IBS comparable to those achieved with a low FODMAP diet¹ — a commonly recommended but restrictive approach. Because VSL#3 is certified FODMAP Friendly, it can also be used alongside a low FODMAP diet for flexible dietary management.

Although both products contain the same 8 probiotic strains, they are formulated and labeled for different purposes. VSL#3® is a refrigerated, ultra-high-potency probiotic medical food for the dietary management of specific GI conditions. VSL4® Gut is a probiotic supplement designed to support digestive comfort, regularity, and overall gut health.

There is no known conflict, but we strongly recommend consulting your healthcare provider first. They will assess your personal digestive condition, current medications and supplements to confirm safe, compatible use of VSL#3® with other gut products.

Medical foods like VSL#3 are specially formulated to manage specific diagnosed gastrointestinal conditions and are meant to be used under healthcare provider supervision. Standard supplements such as VSL4 Gut are for general daily gut wellness, supporting regular digestion without targeting clinical intestinal disorders.