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SD ALCOHOL 40-B.

Avoid / ASTRINGENT, SOLVENT, VISCOSITY CONTROLLING

SD Alcohol 40-B is a denatured ethanol variant primarily utilized as a solvent to homogenize formulations and enhance ingredient absorption. While offering a refreshing sensation and astringent properties, its potential for skin barrier disruption and irritation necessitates careful formulation and use.

Summary

Solvent Astringent Antimicrobial Viscosity Decreasing Penetration Enhancer Preservative

Science

Mechanism of Action

This alcohol derivative functions predominantly as a solvent, effectively dissolving various components such as fragrances, oils, and resins to ensure product consistency and stability. Its rapid evaporation delivers a cooling effect and temporarily tightens skin, minimizing the appearance of pores through its astringent action. SD Alcohol 40-B also serves as a penetration enhancer, transiently compromising the skin barrier to facilitate deeper absorption of active ingredients, and exhibits antimicrobial properties, contributing to product preservation. However, this mechanism can also lead to skin dehydration, lipid depletion, and inflammation, potentially exacerbating oil production in oily skin types.

Research

Clinical Evidence

Medium confidence
Effective range 0.05–12%
Optimal

12%

Key findings

  1. 01 A gel formulation containing 29% SD Alcohol 40-B demonstrated no photoallergy, dermal sensitization, or phototoxic response in human subjects.
  2. 02 A spray liquid with 12% concentration did not induce photoallergy, dermal sensitization, or phototoxic reactions in human subjects and was nonirritating in rabbit vaginal mucosal evaluations.
  3. 03 An irritation study using rabbits with 55.65% SD Alcohol 40-B, denatured with Denatonium Benzoate, yielded only minimal effects.

Transparency

Dusting Analysis

Commonly dusted
Min. effective
12%
Red flag below
12%

Despite its functional benefits as a solvent and penetration enhancer, SD Alcohol 40-B is frequently 'dusted' or avoided in modern precision skincare formulations due to its potential for skin drying, irritation, and barrier disruption, particularly when used frequently or in concentrations exceeding the Cosmetic Ingredient Review (CIR) recommended maximum of 12%.

The Formula

Formulation

Solubility
Both
Optimal pH N/A
0 7 14

Stability

Stable under typical conditions. However, it is highly flammable and must be stored away from heat, sparks, open flames, and hot surfaces.

Synergies

  • Active ingredients (as a penetration enhancer)

Conflicts

  • Strong Oxidizers
  • Inorganic Acids
  • Halogens
  • Alkali metals
  • Ammonia
  • Peroxides
  • Strong acids
  • Strong bases
  • Silver salts
  • Acid chlorides
  • Metal hydrides
  • Hydrazine

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
12%
Sensitization risk Low

The CIR Expert Panel considers SD Alcohol 40-B safe for cosmetic use at concentrations between 0.05% and 12%, provided it is denatured with approved agents like Denatonium Benzoate and t-Butyl Alcohol. The FDA recognizes ethanol (alcohol) as Generally Recognized As Safe (GRAS) for certain food applications and approves its use in OTC antimicrobial drugs. While generally safe within specified limits, concerns persist regarding its potential for drying and irritating the skin, especially with frequent application or higher concentrations.

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy Medium
Comedogenicity Unknown

Our Assessment

Verdict

Avoid

Despite its utility as a solvent and penetration enhancer, SD Alcohol 40-B is generally advised against in precision skincare due to its medium irritancy potential and risk of compromising the skin barrier, especially for dry or sensitive skin types.

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