allergic reaction

EXPLAINER: Everything You Need To Know About Octylisothiazolinone

EXPLAINER: Everything You Need To Know About Octylisothiazolinone

At Cottonique, we believe it's not just the fabric that makes our clothes completely allergy-free. After all, even the tiniest details of your clothes contribute to the overall comfort of your skin. 

Commonly used as an antifungal agent by the leather industry, Octylisothiazolinone (OIT) is both an active ingredient and a type of isothiazolinone preservative that can cause allergic contact dermatitis to people with skin allergies and sensitive skin.

Photo from National Library of Medicine

According to DermNet, OIT is a biocide typically added as a film preservative to protect surfaces or the final coating of manufactured products, which then prevents the growth of bacteria, molds, and fungi. 

This material can be found in many commercial household and industrial products such as:

  • Leather products like belt
  • Rubberized products 
  • Glues
  • Polishes
  • Water-based paints
  • Cleaning products
  • Wood preservatives
  • Metalworking fluids.

Despite its many functions, the OIT becomes a harmful material due to its moderate sensitization potency, which can trigger skin irritations and allergies. Aside from the health issues, the US Environmental Protection Agency also classified OIT as "very highly toxic to aquatic life."

People with skin conditions and sensitivities will develop contact dermatitis upon exposure to OIT, giving itchy, red, and swollen rashes on their faces, hands, torsos, legs, and feet. Some sensitized individuals also develop blisters at some sites.


DermNet stated that those with exposure to OIT can develop sensitivity and subsequent contact allergy. "People with contact allergy to methylisothiazolinone or other types of isothiazolinone can also react to OIT," said DermNet. "Most cases of reported allergic contact dermatitis from OIT are in occupational settings."
The most common people affected by OIT include:

  • Painters
  • Metal-worker
  • Textile workers
  • Mechanics.

Non-occupational contact dermatitis brought by OIT also exists due to the increasing use of the material in the leather and textile industry. 


DermNet reported that once OIT sensitivity has been confirmed through patch testing, avoidance of exposure to any products containing OIT is crucial. “The dermatitis is treated as for any acute dermatitis, by application of a topical corticosteroid and an emollient until the allergic reaction settles,” said the allergy website, adding that antihistamines can also be used to remedy the itching. 


Since most contact dermatitis cases brought on by exposure to OIT happen in workplaces, DermNet said companies should be informed of the dangers of the allergen. If the avoidance of materials seems impossible, we recommend using practical measures and other personal protective equipment to protect the skin and minimize exposure.

DISCLAIMER: The information presented on Cottonique is not, and will never be, intended to be a substitute for professional medical advice, diagnosis, or treatment. All content materials found on this site, from text, treatments, outcomes, charts, graphics, photographs, and study findings, are created and published for general informational purposes only. It should not, in any way, be construed as a standard of care to be followed by a user of the website. 

Thus, readers are encouraged to verify any information obtained from this website with other accurate references and review all information regarding any medical condition or treatment with their physician. As Cottonique strives to help those with allergies live with better days, the hypoallergenic apparel brand encourages everyone to always seek the advice of their physician or other qualified health providers with any questions they may have regarding a medical condition.

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