Methylisothiazolinone is a preservative commonly found in water-based cosmetics and personal care products. It effectively prevents the growth of bacteria and fungi, thereby extending product shelf life and ensuring consumer safety. However, it is a known sensitizer, especially at higher concentrations.
NonePreservativeVeganEvidence: High
BenefitNone 0 / 4
RiskSerious 3.5 / 4
Sensitization
Irritation
Rated by SpottyLabs' ingredient methodology, independent of brands.
Things to watch
Can cause skin sensitization and allergic reactions
High risk of contact dermatitis
Spot questionable ingredients in seconds
SpottyLabs scans any skincare product and rates every ingredient for benefit, risk and safety. Free and independent — no brand is paying us.
App coming soon
Products with Methylisothiazolinone
Original Root Stimulator Olive Oil Moisturizing Hair Lotion
What is Methylisothiazolinone's role in skincare products?
Methylisothiazolinone functions as a preservative in skincare products, preventing the proliferation of bacteria, yeasts, and molds. This helps to maintain the product's integrity and safety throughout its use.
Why is Methylisothiazolinone a concern for some people?
Methylisothiazolinone is a significant concern for some individuals because it is a potent sensitizer, meaning it can cause allergic contact dermatitis. Regulatory bodies have restricted its use and concentration in cosmetic products due to the high incidence of allergic reactions.
Spotty Labs