For skin, the clearest single trial is for a postbiotic lysate cream, though it was small and run by L'Oréal. Prebiotics have a couple of small trials, and live probiotic skincare is still mostly research. Probiotic capsules haven't been shown to treat eczema. Two of the hopeful skin trials were run by scientists at companies that sell or use the ingredient.
You've seen "probiotic" on a serum, a cleanser and a jar of capsules in the same week. Your skin stings, flares or breaks out, and you want to know which of these, if any, is worth trying. You'd also like to know whether the cream or the capsule is the better bet.
What's the Difference Between Prebiotics, Probiotics and Postbiotics?
Prebiotics feed the bacteria already on your skin, probiotics are live bacteria, and postbiotics are bacteria that are no longer alive. On a label, that difference matters more than the word on the front of the bottle.
- Prebiotics are usually sugars, such as oligosaccharides, meant to nourish the microbes you already have.
- Probiotics are live microorganisms. In skincare, the hard part is keeping them alive in the jar.
- Postbiotics are, in the words of an international scientific panel, a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host."
That same panel's definition leaves out purified compounds made without any bacterial cell material. So lactic acid on its own is an acid, not a postbiotic, even when a brand calls it one. The panel says bacterial lysates, which are broken-up cells, may count as postbiotics if a health benefit is documented.
For the basics of what lives on your face, what the skin microbiome is covers the background.
Does Probiotic Skincare Contain Live Bacteria?
Not always, and the ingredient list usually tells you. If the bacteria are listed as a "lysate," that ingredient isn't alive.
That isn't a flaw, because live bacteria are hard to keep in a cream. A 2022 review of topical probiotics notes that cosmetic preservatives can potentially affect the probiotic strain viability. Standard preservative testing is also a major hurdle for these products. The same review found a lack of validated clinical data on how well topical probiotics work.
A lysate sidesteps all of that. It doesn't need to survive, settle on your skin or win a fight with the bacteria already there.
Which Has the Best Evidence: Cream or Capsule?
Neither has strong evidence. The wins so far are small trials on sensitive skin, for creams and capsules alike, while the big review of capsules for eczema came up empty. Here are the human trials side by side, with who ran each one.
| Type and route | Who was studied | What happened | Who ran it |
|---|---|---|---|
| Postbiotic cream (10% Bifidobacterium longum lysate) | 66 women with reactive skin, two months | Less stinging on a lactic acid test, less dryness by day 29 | L'Oréal Research |
| Prebiotic lotion (alpha-gluco-oligosaccharides, tested with collagen tripeptide F) | 40 women aged 30 to 59 with sensitive atopic skin, four weeks | Less water loss, better hydration | Berardesca et al.; trial funding not stated in the review |
| Live probiotic (Staphylococcus hominis A9) | 54 adults with S. aureus-positive eczema, one week (phase 1 safety trial) | Fewer S. aureus bacteria, but eczema no better than placebo overall | NIH-funded; two authors co-invented the treatment, and one holds company equity |
| Probiotic capsule (Lactobacillus paracasei ST11) | 64 women with reactive skin, two months | Less sensitivity on a capsaicin test, faster barrier recovery | L'Oréal and Nestlé scientists |
| Probiotic capsules for eczema | 39 trials, 2,599 people up to age 55 | Little or no difference in symptoms | Cochrane review; 10 included trials were funded by probiotic suppliers, and two authors declared ties to probiotic makers |
The prebiotic trial comes from a 2025 review of prebiotic oligosaccharides in skin health. Its authors point to the scarcity of dedicated studies and to methodological inconsistencies between them. Another small trial in the review tested a serum in 60 healthy women aged 40 to 60.
Notice the pattern. Both reactive skin trials, one cream and one capsule, came from scientists at companies that develop or sell the ingredients. That doesn't make the results wrong, but treat them as a start until independent groups report the same.
The wider picture looks similar. A King's College London team mapped 516 studies on probiotic and prebiotic supplements and skin, working with Yakult, a probiotic company. Eczema made up 330 of them, and infants were the focus of 42% of the human studies. The team's verdict was that the evidence isn't quite there yet.
