About VSL#3

VSL#3 is a high potency probiotic medical food designated for the dietary management of ulcerative colitis, irritable bowel syndrome and an  ileal pouch. It is a medical food and must not be confused with an over-the-counter dietary supplement. You need to be under medical supervision. VSL#3 is dispensed by a pharmacist.


Unlike other probiotics, VSL#3 is a superior high potency probiotic medical food. The number of bacteria is important.

  • VSL#3 is 10 times more potent than the average probiotic (average CFU = 15.5 billion) – The average probiotic (according to IRI data 09/12) contains about 4.3 billion CFU.
  • VSL#3 formulations contain from 225 billion to 900 billion bacteria per serving (available by prescription).
  • VSL#3 is one of the most potent probiotics in the world.

Live Bacteria

Refrigeration preserves the live bacteria and helps maintain high potency.

  • VSL#3 is a refrigerated probiotic.
  • VSL#3 is manufactured with a carefully designed formulation of billions of bacteria that maintain vitality.
  • VSL#3 has triple layer packets to prevent heat, light, moisture and contamination to maintain potency. The patented cap on the capsule bottle also prevents heat, light, moisture and contamination from entering the bottle, allowing us to forgo needing a second seal on the capsule bottle.


One of the effects of probiotics is that they are highly strain-specific. Simultaneous administration of multiple bacterial strains in specified ratios may provide a range of benefits that cannot be achieved with single-strain probiotics.

  • VSL#3’s unique synergistic composition, with 8 diverse strains of bacteria, has significant advantages in terms of metabolic and functional activities.
  • VSL#3’s 3 genus and 8 species of live bacteria have been carefully cultivated and mixed proportionally to optimize the probiotic content.
  • VSL#3 has the highest concentration of bacteria (compared to other probiotics) and the unique combination of strains confers upon VSL#3 an unusual degree of potency.

A Combination of 8 Diverse Strains of Live Probiotic Bacteria

Genus Species
Streptococcus thermophilus
Bifidobacterium breve
Bifidobacterium longum*
Bifidobacterium infantis*
Lactobacillus acidophilus
Lactobacillus plantarum
Lactobacillus paracasei
Lactobacillus delbrueckii subsp. bulgaricus †

* Reclassified as B. lactis
† Recently reclassified as L. helveticus

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