Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: July 1, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate?

Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate is a liquid obtained after fermenting the lichen Usnea longissima with two friendly microbes, Lactobacillus and Saccharomyces. The fermentation process breaks down the lichen into skin loving molecules such as organic acids, amino acids and antioxidant compounds while the final product is filtered to remove any solid debris. Usnea longissima has been valued in traditional self care for its soothing properties, and formulators began experimenting with it in modern cosmetics once fermentation techniques proved they could boost its benefits and make it gentler for skin.

To make the filtrate, harvested Usnea longissima is cleaned and blended into a nutrient solution. Lactobacillus and Saccharomyces are added under controlled temperature and pH, allowing them to ferment the mixture for several days. After fermentation, the liquid is strained and purified, leaving a clear filtrate rich in bioactive substances.

You will typically see this ingredient in hydrating sheet masks, lightweight serums, anti aging creams, soothing moisturizers and post sun care products. Its multitasking nature also makes it popular in calming toners and skin barrier repair treatments.

Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate’s Cosmetic Benefits/Uses

This fermented filtrate offers several perks that help keep skin healthy and resilient

  • Antioxidant: Helps neutralize free radicals from pollution and UV exposure which can lead to dullness and premature lines, keeping the complexion brighter and more even toned
  • Skin Conditioning: Supplies skin with moisturising components and gentle acids that smooth texture, soften rough patches and leave the surface feeling supple
  • Skin Protecting: Supports the skin barrier by reinforcing the outer layer, reducing moisture loss and helping shield against everyday irritants

Who Can Use Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate

This ferment filtrate is considered gentle enough for all skin types including oily, dry, combination and sensitive because it supplies lightweight hydration and barrier friendly antioxidants without heavy oils or common irritants. Those with extremely reactive skin should still check the full product formula to ensure there are no added fragrances or other triggers.

The ingredient is sourced from a plant lichen and cultured with two microorganisms that are not animal derived, so products featuring it are suitable for vegans and vegetarians provided the rest of the formula follows the same standard.

No data suggest that the filtrate poses a specific risk to pregnant or breastfeeding women when used topically, yet this is not medical advice. Anyone who is expecting or nursing should review all skincare products with a qualified healthcare professional to be fully confident in their routine.

Unlike exfoliating acids or retinoids, this ferment does not increase photosensitivity. Daily sunscreen is still essential for overall skin health but extra sun precautions are not required solely because of this ingredient.

It has a light, water like texture that layers well with other actives, making it easy to incorporate into morning or evening routines without pilling or heaviness.

Potential Side Effects/Adverse Reactions

Responses to topical Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate differ from person to person. The following lists potential side effects though most users will not encounter them when the ingredient is properly formulated and applied.

  • Mild redness or stinging on very compromised or freshly exfoliated skin
  • Allergic reaction such as itching or swelling if an individual is sensitized to lichen derivatives or fermentation byproducts
  • Contact dermatitis in rare cases due to preservative systems paired with the ferment rather than the ferment itself

If any persistent irritation or unexpected reaction occurs discontinue use and seek advice from a healthcare professional.

Comedogenic Rating

Rating: 0/5. Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate is a watery, oil free extract packed with small, bioavailable molecules that do not clog pores. It leaves no occlusive film on the skin and absorbs quickly, which is why it earns the lowest possible score. This makes it well suited for acne prone or congestion prone skin types. Only note that the overall pore friendliness of a finished product depends on everything else in the formula, so rich creams or heavy sunscreens that include the ferment may behave differently.

Summary

Lactobacillus/Saccharomyces/Usnea Longissima Ferment Filtrate delivers antioxidant, skin conditioning and skin protecting benefits. Fermentation breaks Usnea longissima into nourishing amino acids, gentle organic acids and defensive polyphenols that mop up free radicals, smooth rough texture and bolster the moisture barrier. While not yet a mainstream buzzword it is gaining traction in K beauty inspired serums, sheet masks and calming moisturizers due to the rising interest in fermented ingredients. Overall it is considered very safe with low irritation and zero comedogenicity but as with any new skincare addition a quick patch test is wise to confirm personal compatibility.

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