Methylchloroisothiazolinone
What Methylchloroisothiazolinone is & what it does
A strong preservative used with methylisothiazolinone (the Kathon blend), effective at tiny levels but a recognized allergen. Its use is restricted, mainly to rinse-off products.
What does Methylchloroisothiazolinone do in skincare?
Methylchloroisothiazolinone is used as a preservative in water-based cosmetic products. Its job is to prevent the growth of bacteria, mold, and yeast so a formula stays stable and safe to use over time. It is typically used at very low concentrations, often paired with methylisothiazolinone.
Is Methylchloroisothiazolinone safe?
Methylchloroisothiazolinone is permitted as a preservative within strict concentration limits set by cosmetic regulations. It is, however, a known contact allergen for some people, and its use is generally restricted to rinse-off products in many regions. People with sensitive skin or a history of preservative allergy may want to avoid it or consult a professional.
Is Methylchloroisothiazolinone natural or synthetic?
Methylchloroisothiazolinone is a synthetic compound produced for use as a cosmetic preservative. It does not occur naturally in the form used in products. It is added in small, regulated amounts to keep formulas free of microbial growth.
Sunscreens with Methylchloroisothiazolinone
We rate 19 sunscreens that contain it, showing the top 10 by overall score:
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Earth Rhythm Coconut Milk SPF-50 Butter Lotion
80/100
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Earthly Wellness Essence Sun Gel Sunscreen SPF 50 Pa++++
71/100
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Earth Rhythm Mineral Sunserum SPF 50
67/100
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4ever Skin Naturals Daily Moisturising And Brightening Sun Protection Cream
66/100
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Belo Sunexpert Face Cover Spf 40
64/100
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Lacto Calamine Dewy Sunscreen SPF 50 Pa+++
62/100
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Clinica Sun Protection SPF 50+
59/100
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Banana Boat Ultra Sport Reef Friendly Sunscreen Lotion, SPF 50
58/100
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Banana Boat Sport Performance Sunscreen Lotion Spf 30
57/100
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Oshea Uvshield Sun Block Formula SPF 50
57/100