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Ingredient directory

Castoreum Oil

An aromatic secretion derived from beaver castor sacs, traditionally utilized in high-end perfumery for its deep, leathery notes. In precision skincare, it serves as a sophisticated fixative that stabilizes volatile aromatic compounds while offering secondary botanical-derived skin benefits.

Directory entry · Individual source review pending

This profile is awaiting an individual source review. Treat its ratings, dose estimates and compatibility labels as provisional; they are not medical advice or proof of a finished product’s effects.

Fragrance Fixative Masking agent

Science

Mechanism of Action

It functions primarily by lowering the vapor pressure of more volatile ingredients, ensuring a sustained release of scent over time. Due to the beaver's diet of willow and birch, the oil naturally contains salicin and various phenols, which provide mild antimicrobial and anti-inflammatory properties when applied topically.

Research

Clinical Evidence

Medium confidence
Effective range 0.1–5%
Optimal

4%

Key findings

  1. 01 Animal-based dermal toxicity assessments confirm the extract is non-toxic and non-irritating to the skin.
  2. 02 Human repeat insult patch testing (HRIPT) indicates a lack of phototoxicity or sensitization potential.
  3. 03 Studies highlight the presence of salicylic acid derivatives (from salicin) which contribute to a weak antibacterial effect.

Transparency

Dusting Analysis

Commonly dusted
Min. effective
0.5%
Red flag below
0.1%

In most skincare products, castoreum is included at infinitesimal amounts solely for its scent profile. While it has historical medicinal use, 'dusting' occurs when it is marketed for antibacterial or anti-aging benefits without reaching the 4% concentration used in clinical safety assessments.

The Formula

Formulation

Solubility
Oil
Optimal pH 6.5 – 7.5
0 7 14

Stability

Highly stable in neutral pH environments but prone to precipitation in highly acidic solutions. It is soluble in oils and alcohol tinctures but nearly insoluble in water.

Synergies

  • Volatile essential oils
  • Lipid-based delivery systems
  • Phenolic compounds

Conflicts

  • Strong oxidizing agents
  • Highly acidic formulations (pH < 5.0)

Safety

Safety Profile

CIR Status
Safe as used
Max tested
5%
Sensitization risk Low

Recognized as GRAS by the FDA. The 5% concentration limit is generally applied to the fragrance compound itself rather than the finished cosmetic emulsion.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
No Sensitive
Irritancy Low
Comedogenicity Unknown

Our Assessment

Verdict

Optional

While an excellent natural fixative for luxury scent profiles, its direct clinical benefits for skin health remain secondary and largely unproven compared to modern synthetics.

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