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OCTYLISOTHIAZOLINONE.

Avoid CAS 26530-20-1 / ANTIMICROBIAL

Octylisothiazolinone (OIT) is a potent, broad-spectrum microbicide effective against bacteria, fungi, and mold. Despite its preservative capabilities, its significant potential for skin sensitization and irritation generally leads to its exclusion from precision skincare formulations.

Preservative Antimicrobial Antifungal

Science

Operating as a broad-spectrum microbicide, Octylisothiazolinone disrupts microbial viability by irreversibly reacting with the crucial thiol groups within enzymes and proteins of microorganisms. This interaction compromises vital cellular functions, leading to definitive cell death and thus effectively preventing unwanted microbial proliferation.


Research

Insufficient-data confidence
Effective range N/A
Optimal

N/A


Transparency

Commonly dusted
Min. effective
0.05%
Red flag below
0.05%

While an effective biocide, Octylisothiazolinone is identified as a relevant sensitizer. The European Union has not approved its use as an active substance in pesticides, and products containing 0.05% (500 ppm) or more require labeling due to its sensitization potential. Its presence in skincare is highly uncommon and generally discouraged due to these significant risks, making its inclusion in such products a potential 'dusting' concern if alternative, safer preservatives are available.


The Formula

Solubility
Both
Optimal pH 4 – 10
0 7 14

Stability

Octylisothiazolinone demonstrates robust stability across a wide range of temperatures and pH levels, specifically within a pH range of 4 to 10 in aqueous and industrial systems. Optimal performance is typically observed under acidic pH conditions. It is important to note that stability in highly concentrated formulations may vary, necessitating thorough pre-commercialization testing.

Conflicts

  • Strong reducing agents (e.g., sulfides, mercaptans, bisulfites, metabisulfites)
  • Strong oxidizing agents (e.g., hypochlorites)
  • Amines (compatibility may vary by type, concentration, and pH)

Safety

CIR Status
Not reviewed
Sensitization risk Moderate

Octylisothiazolinone is identified as a relevant sensitizer with moderate potency, capable of inducing skin irritations and allergic contact dermatitis. There is no specific safety assessment by the Cosmetic Ingredient Review (CIR) for its use in cosmetics. The Scientific Committee on Consumer Safety (SCCS) has not explicitly reviewed it for cosmetic applications, and it is no longer approved for certain uses within the European Union, being listed as 'not approved' in the EU Pesticides Database. Products containing 0.05% (500 ppm) or more necessitate specific labeling due to potential sensitization. It is generally not found in skin care products.


Your Skin

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

Our Assessment

Avoid

Due to its moderate sensitization potential, lack of cosmetic-specific safety review, and general absence from skincare formulations, Octylisothiazolinone is an ingredient best avoided in precision skincare.


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References