Streptococcus Thermophilus Lysate: 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: June 30, 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 Streptococcus Thermophilus Lysate?

Streptococcus Thermophilus Lysate comes from Streptococcus thermophilus, a friendly bacterium best known for helping ferment milk into yogurt. In skin care the cells are grown in a controlled fermentation tank, allowed to multiply, then broken apart in a process called lysis that uses heat or enzymes. This releases a rich mix of peptides, amino acids, polysaccharides and naturally occurring enzymes. After the broken cells are filtered and dried the lysate becomes a stable powder or liquid that can be blended into creams and serums.

The idea of putting beneficial bacterial extracts on skin gained traction in the early 2000s when researchers noticed that “postbiotic” fragments could help calm and support the skin barrier. Brands soon added Streptococcus Thermophilus Lysate to formulations aimed at reinforcing the microbiome and reducing moisture loss. Today you will commonly find it in moisturizers, barrier repair creams, soothing masks, anti aging serums and after-sun treatments.

Streptococcus Thermophilus Lysate’s Cosmetic Benefits/Uses

Its main role is skin protecting. By supplying skin-friendly peptides and polysaccharides the lysate helps strengthen the outer barrier, which can reduce transepidermal water loss, improve softness and make skin less reactive to everyday stressors.

Who Can Use Streptococcus Thermophilus Lysate

This lysate is gentle enough for nearly all skin types. Dry sensitive or mature skin may notice the biggest boost because the ingredient focuses on barrier support and moisture retention. Oily and acne-prone users can still benefit since the lysate is lightweight and does not add extra oil. There are no known reasons it would be unsuitable for darker skin tones or reactive skin as long as the overall formula is well balanced.

The raw material comes from a bacterial culture rather than an animal source so it is generally seen as vegan and vegetarian friendly. Some suppliers do grow the bacteria on a dairy-based medium though, so strict vegans may want to confirm sourcing details with the brand.

No research links topical Streptococcus Thermophilus Lysate to problems in pregnancy or while breastfeeding. Still, this information is not medical advice and anyone who is pregnant or nursing should ask a doctor before adding new products to a routine just to be safe.

The lysate does not raise the skin’s sensitivity to sunlight so extra daytime precautions are not required beyond a normal broad-spectrum sunscreen.

Potential Side Effects/Adverse Reactions

Responses to any cosmetic ingredient can differ from person to person. The points below list potential issues that could occur with topical Streptococcus Thermophilus Lysate though most users will not experience them when the ingredient is included at standard levels and the product is properly formulated.

  • Mild redness or stinging
  • Temporary itching on very sensitive skin
  • Allergic reaction in individuals already sensitised to Streptococcus species
  • Breakouts if the finished product contains comedogenic companion ingredients

If irritation or any unexpected reaction occurs stop use right away and consult a healthcare professional or dermatologist.

Comedogenic Rating

Rating: 0 / 5 – Streptococcus Thermophilus Lysate is a water based ferment extract that contains mostly peptides, amino acids and sugars rather than heavy oils or waxes that can block pores. It does not sit on the surface forming a film that traps sebum so it is considered non-comedogenic. Because of that it is generally suitable for acne prone skin. No studies or user reports link the lysate itself to clogged pores, though finished products can still cause breakouts if they include other pore-clogging ingredients.

Summary

Streptococcus Thermophilus Lysate is prized for skin protecting action. By delivering small peptides, polysaccharides and enzymes it helps fortify the skin barrier, cut down water loss, soften texture and calm reactivity from everyday stressors. It shows up most often in moisturizers and soothing serums, yet it is still a niche ingredient compared with bigger names like niacinamide or hyaluronic acid. Safety data is reassuring with low risk of irritation or pore blockage for most users. As with any new skincare product it is smart to patch test first to catch rare sensitivities.

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