Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean 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: June 23, 2025
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All information on this page is verified using The Personal Care Products Council's (PCPC) INCI database. Our ingredient analyses are based exclusively on PCPC's technical data to ensure accuracy and reliability.

What Is Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean Ferment Filtrate?

Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean Ferment Filtrate is a skin and hair care ingredient made by fermenting self-heal (Prunella vulgaris) flowers and leaves together with soybeans. Two well-studied microorganisms, Bacillus and Monascus, are added to this plant mix. As they digest the plant material they create a liquid rich in amino acids, peptides, natural sugars, and soothing plant compounds. After fermentation the mixture is filtered, leaving behind a clear nutrient-packed fluid that is easy to blend into creams, serums, toners, shampoos, and scalp treatments.

The idea of using fermented botanicals in beauty care comes from traditional Asian fermentation practices where rice water, soy, and herbs were aged to improve skin feel. Modern labs picked up the concept because fermentation can break big plant molecules into smaller ones that skin and hair absorb more easily. Today this filtrate appears in lightweight moisturizers, balancing toners, sebum-control spot treatments, soothing sheet masks, anti-aging lotions, and scalp or hair softening products.

Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean Ferment Filtrate’s Cosmetic Benefits/Uses

This multitasking ferment brings several helpful actions to beauty formulas:

  • Anti-Sebum: Helps balance excess oil so skin looks less shiny and pores stay clearer. Often used in products for combination or oily skin.
  • Hair Conditioning: Smooths the hair cuticle making strands feel softer and easier to detangle while adding light hydration without weight.
  • Skin Conditioning: Supplies moisture and calming plant nutrients that leave skin feeling supple and comfortable.
  • Emollient: Forms a thin breathable layer that locks in water giving both skin and hair a smoother texture and healthier appearance.

Who Can Use Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean Ferment Filtrate

This ferment filtrate is generally suitable for normal, combination and oily skin because it helps balance sebum while still offering light hydration. Dry or very dry skin can certainly use it too but may want a richer cream on top since the ingredient itself is not highly occlusive. Sensitive skin usually tolerates it thanks to its soothing plant compounds though anyone with a known sensitivity to fermented ingredients should proceed with extra care.

The ingredient is produced entirely from plants, soybeans and microorganisms with no animal derived matter, making it appropriate for both vegetarians and vegans.

No data show specific risks for pregnant or breastfeeding women when this ferment is used topically at typical cosmetic concentrations. That said this is not medical advice and anyone who is pregnant or nursing should have their doctor review any skincare product before use just to be safe.

The filtrate does not cause photosensitivity so it will not make skin more prone to sunburn. It is also fragrance free by nature and has a very low scent profile which can be helpful for those avoiding added perfume.

Potential Side Effects/Adverse Reactions

Individual reactions can vary and the following list covers potential side effects rather than what most people will experience. When formulated correctly the vast majority of users have no issues.

  • Skin irritation such as mild stinging or burning
  • Redness or flushing in sensitive skin
  • Itching or localized rash indicating allergic contact dermatitis
  • Acne flare in very reactive acne-prone skin
  • Histamine-type response like hives in those intolerant to fermented ingredients
  • Temporary discoloration of light fabrics or towels due to natural pigments from Monascus if product has a pink tint

If any of these effects appear stop using the product and consult a healthcare professional or dermatologist.

Comedogenic Rating

Rating: 1 (very low likelihood of clogging pores)

This filtrate is mostly water soluble and contains small fermented peptides sugars and soothing plant compounds rather than heavy oils or waxes. Soybean components are largely broken down during fermentation so the residue is light and non greasy. Together these factors keep the molecule size small and easy to rinse away which is why it earns a rating of 1.

Suitable for acne-prone or breakout-prone skin in most cases.

Because the final color can range from pale pink to amber formulas that use it might contain trace natural pigments from Monascus but these do not add significant pore-clogging risk.

Summary

Bacillus/Monascus/Prunella Vulgaris Flower/Leaf/Soybean Ferment Filtrate works as an anti sebum agent a skin and hair conditioner and a light emollient. Fermentation splits larger plant proteins and sugars into smaller molecules that help regulate oil production soothe irritation draw in moisture and smooth the surface of both skin and hair. These benefits make it a flexible add-on in toners lotions serums scalp mists and lightweight conditioners.

While fermentation based extracts are becoming more common this specific blend is still a niche ingredient showing up mainly in K-beauty inspired formulations and select clean beauty lines. Its gentle profile and plant origin attract formulators looking for vegan multifunctional actives.

Current safety data and user reports show a low risk of irritation and virtually no systemic concerns so most people can use it with confidence. As with any new cosmetic ingredient it is wise to patch test a fresh product first to rule out individual sensitivity.

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