Methylisothiazolinone (MIT) is a synthetic preservative that is commonly used in personal care products and cosmetics due to its ability to inhibit bacterial and fungal growth. It extends the shelf life of products and is specifically beneficial for water-based cosmetics. However, it comes at a cost - Methylisothiazolinone has garnered attention for potential skin sensitization issues, leading to regulatory scrutiny and label warnings. In high concentrations, this ingredient can cause skin burns and severe allergies. Therefore, a lot of personal care brands are opting for alternatives such as Phenoxyethanol in leave-on products. Other names of Methylisothiazolinone include Neolone 950 preservative, 2-methyl-4-isothiazoline-3-one, MI, Microcare MT, and OriStar MIT.
Origin
Methylisothiazolinone is produced by the chemical reaction between chloromethylisothiazolinone and methylamine. The ingredient is then purified for use in cosmetics and personal care products. In its raw form, Methylisothiazolinone appears as a white solid. It has the chemical formula C4H5NOS.
Safety profile
Methylisothiazolinone can be a hazardous ingredient when used in high concentrations as it causes severe allergies and skin sensitization. Even in lower concentrations, patch testing is necessary to ensure safe usage. In case of any adverse reactions, discontinue use and contact a dermatologist. Today, the use of Methylisothiazolinone is largely limited to rinse-off products in order to minimize potential risks.