Get a Free 5ml Mini Now Free 5ml Mini With Every Order of The Mantle

BENZISOTHIAZOLINONE.

Avoid CAS 2634-33-5 / ANTIMICROBIAL

Benzisothiazolinone (BIT) is a synthetic antimicrobial biocide primarily utilized as a preservative to prevent microbial contamination in aqueous solutions. While highly effective at stabilizing industrial and household water-based formulas, its use in high-performance skincare is increasingly scrutinized due to its potential as a skin sensitizer.

preservative antimicrobial antibacterial

Science

As a member of the isothiazolinone family, it functions as a thiol-reactant. It penetrates the cell membranes of microbes and reacts with the essential sulfhydryl groups of enzymes, specifically targeting those in the Krebs cycle. This interaction halts cellular respiration and protein synthesis, resulting in the rapid death of Gram-positive and Gram-negative bacteria, yeast, and fungi.


Research

Medium confidence
Effective range 0.005–0.1%
Optimal

0.01%

Key findings

  1. 01 Dermatological screening (IVDK 2000-2019) indicated a 2.47% positive reaction rate among dermatitis patients, confirming its status as a notable allergen.
  2. 02 SCCS evaluations determined that even trace amounts as low as 20 ppm (0.002%) in consumer products like PVC gloves can trigger sensitization and allergic contact dermatitis.

Transparency

Not commonly dusted
Min. effective
0.005%
Red flag below
0.01%

This ingredient is rarely 'dusted' because it is not an active; rather, it is a preservative. However, because it lacks a clearly defined safe threshold for sensitization in leave-on cosmetics, any concentration exceeding 0.01% in skincare is a potential concern for skin health.


The Formula

Solubility
Water
Optimal pH 4 – 12
0 7 14

Stability

Exhibits exceptional thermal stability up to 100°C and maintains structural integrity in highly alkaline environments where other preservatives might fail.

Conflicts

  • Strong oxidizing agents
  • Nucleophiles
  • Reducing agents like sulfites and bisulfites
  • Persalts

Safety

CIR Status
Not reviewed
Max tested
0.01%
Sensitization risk High

The EU's SCCS concluded that a safe exposure level for skin sensitization has not been established for cosmetics. It is more prevalent in rinse-off household products than in precision skincare.


Your Skin

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

Our Assessment

Avoid

While a powerful antimicrobial, its high risk of sensitization and lack of a proven safe threshold make it unsuitable for modern, precision-targeted skincare.


Related

Finding similar ingredients…