Of course. Given your interest in gut health, that’s a great question. VSL#3 is a well-known name in the world of probiotics. Here’s some more information about it.
What is VSL#3?
VSL#3 is a high-potency probiotic medical food. This means it’s a specially formulated product intended to be used under the supervision of a doctor for the dietary management of specific medical conditions. It’s known for having an extremely high concentration of live bacteria—hundreds of billions of colony-forming units (CFUs) per dose—from multiple different strains.
What is it used for?
Clinically, it has been studied for its role in managing:
- Ulcerative Colitis (UC): To help maintain remission.
- Irritable Bowel Syndrome (IBS): To help manage symptoms like bloating and gas.
- Ileal Pouch Pouchitis: An inflammation that can occur after surgery for ulcerative colitis.

Important Formulation Change
This is a critical point to be aware of: The product currently sold under the brand name VSL#3 in the United States has a different formulation than the one used in the vast majority of the original clinical studies that made the product famous.
Due to a legal and business separation, the original inventor of the formulation (Professor Claudio De Simone) is no longer affiliated with the VSL#3 brand. The original, extensively studied formula is now sold under the brand name Visbiome®.
Therefore, if you are reading research or studies conducted before 2016 on VSL#3, the product being studied is what is now known as Visbiome.
Common Side Effects
Like many high-dose probiotics, the most common side effect is mild bloating or gas, especially during the first few days as your gut microbiome adjusts.
Disclaimer: This information is for educational purposes only and is not medical advice. Given your health history, it is essential to speak with your gastroenterologist or another healthcare professional before starting any new supplement or medical food like VSL#3 or Visbiome. They can help you determine if it's appropriate for your specific condition and needs.