Ingredient · Updated
Methylisothiazolinone
Found in 9 productsSee all
Seventh Generation Dishwasher Detergent Gel Lemon Scent 
Method Daily Shower Spray Eucalyptus Mint 
Seventh Generation Liquid Laundry Detergent - Free & Clear - 90 fl oz 
Safely Multi-Surface Cleaning Wipes Calm 
Multi Surface Peppermint Sage Cleaning Wipes 
Arm & Hammer OxiClean Stain Fighters Detergent 
Sun Bum Signature SPF 30 Lotion 
Coppertone Sport Sunscreen Lotion SPF 50 What is Methylisothiazolinone?
Methylisothiazolinone is a chemical compound used as a preservative. It is commonly found in personal care products, household cleaners, and industrial settings to prevent the growth of bacteria and fungi. It is synthesized through a series of chemical reactions involving formaldehyde, cyanide, and other compounds.
This preservative is favored for its effectiveness in low concentrations and its broad-spectrum antimicrobial properties. However, there has been concern regarding its potential to cause allergic reactions, particularly skin irritations. The evidence is mixed, with some studies pointing to significant risks for sensitive individuals.
When you see methylisothiazolinone on a label, it's important to recognize that it is added to extend the shelf life of products. Those with sensitive skin or known allergies should approach products containing it with caution.
Commonly found in: sunscreen, shampoos, lotions, liquid soaps, dishwasher detergents, household cleaners
What to watch
- Linked to skin allergies, especially in leave-on products.
- Potential for causing inflammatory skin reactions in sensitive individuals.
The FDA does not specifically regulate methylisothiazolinone by itself in cosmetics but emphasizes labeling for consumer awareness.
Research indicates a risk of skin sensitization, though some studies show it is safe in rinse-off formulations.
Methylisothiazolinone is a synthetic preservative and is not derived from animal sources, making it suitable for vegan use.
Sources: Safety Assessment of Methylisothiazolinone as Used in Cosmetics
Scout's take
Severe contact allergen. American Contact Dermatitis Society named MI 'Contact Allergen of the Year' in 2013. EU restricts in leave-on cosmetics.
The case against
Methylisothiazolinone can cause skin sensitization, allergic reactions, and irritation.
from the analysis of Sun Bum Signature SPF 30 Lotion · echoed in 1 other analysisIt is a potent skin sensitizer and can cause severe allergic reactions.
from the analysis of Arm & Hammer OxiClean Stain Fighters Detergent · echoed in 1 other analysisIt is associated with allergic reactions and contact dermatitis.
from the analysis of Method Daily Shower Spray Eucalyptus MintHigh risk of skin sensitization and allergic reactions.
from the analysis of Multi Surface Peppermint Sage Cleaning WipesHigh risk of causing skin allergies and irritation.
from the analysis of Seventh Generation Liquid Laundry Detergent - Free & Clear - 90 fl ozThe case for
It prevents microbial growth, extending the shelf life of the product.
from the analysis of Seventh Generation Dishwasher Detergent Gel Lemon Scent · echoed in 1 other analysisProvides effective preservation against microbial contamination.
from the analysis of Seventh Generation Liquid Laundry Detergent - Free & Clear - 90 fl oz · echoed in 1 other analysisIt helps in preserving the product by preventing microbial contamination.
from the analysis of Method Daily Shower Spray Eucalyptus MintIt helps preserve the product by preventing microbial growth.
from the analysis of Arm & Hammer OxiClean Stain Fighters DetergentProvides preservation against microbial growth.
from the analysis of Multi Surface Peppermint Sage Cleaning WipesMore from Scout's analyses
Methylisothiazolinone is a preservative known for its strong antimicrobial properties but is also a leading cause of contact allergies. It is highly criticized for its potential to cause skin irritation and allergic reactions. Its allergenic potential outweighs its preservative benefits.
from the analysis of Seventh Generation Liquid Laundry Detergent - Free & Clear - 90 fl ozMethylisothiazolinone is used as a preservative in cosmetics. It is effective at preventing microbial growth but is known to cause skin sensitization and allergic reactions. It is often criticized for its potential to cause skin irritation and allergic reactions.
from the analysis of Sun Bum Signature SPF 30 LotionMethylisothiazolinone is a preservative known for its effectiveness against bacteria and fungi. However, it is a strong allergen and can cause contact dermatitis. It is considered a leading cause of allergic reactions in personal care products.
from the analysis of Multi Surface Peppermint Sage Cleaning WipesAll 9 products with Methylisothiazolinone
Where Methylisothiazolinone shows up
- Surface Cleaners 3 products
- Sunscreen 3 products
- Laundry 2 products
- Dishwasher 1 product
Higher-scoring picks without Methylisothiazolinone
Products from the same categories whose analyzed ingredient list does not include Methylisothiazolinone, scoring 80 or above.
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