Ingredient review
Diiodomethyltolylsulfone
INCI: DIIODOMETHYLTOLYLSULFONE
An effective preservative but can be a skin sensitizer, so it's best suited for rinse-off products or low concentrations.
In plain English
Diiodomethyltolylsulfone is a man-made preservative that stops bacteria, yeast, and mold from growing in your skincare products. It's often used in small amounts to keep formulas fresh and safe to use over time. Because it can cause skin irritation or allergic reactions in some people, it's more common in products that you wash off rather than leave on your skin.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Diiodomethyltolylsulfone can be useful, but watch for some irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Diiodomethyltolylsulfone.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A synthetic organic compound with strong antimicrobial properties, primarily used as a preservative in cosmetics and industrial products.
How it works
It works by disrupting the cell walls and metabolic processes of microorganisms, effectively killing or stopping their growth. This helps extend the shelf life of the product and prevents contamination during use.
Pros
Effective at low levels
Works well in tiny amounts, so it doesn't overwhelm a formula or add heavy ingredients.
Broad-spectrum protection
Fights bacteria, yeast, and mold, keeping your product safe from contamination.
Cons and cautions
Skin sensitization risk
Can cause allergic reactions or irritation, especially in leave-on products or for those with sensitive skin.
Limited use in natural products
As a synthetic ingredient, it doesn't fit into natural or organic formulations, which may be a drawback for some consumers.
Best for
- People using rinse-off products like shampoos and body washes
- Those without known sensitivities to preservatives
Use caution if
- Individuals with very sensitive or reactive skin
- Anyone with a known allergy to iodinated compounds
Usage tips
Safety summary
Generally safe at low concentrations in rinse-off products, but poses a moderate risk of skin sensitization. Avoid if you have known allergies to iodine or preservatives.
Research notes
Studies confirm its effectiveness as a preservative, but also highlight its potential as a contact allergen. More research is needed on long-term skin exposure effects.
Common label clues
- Typical concentration
- 0.01% to 0.1%
- Regulatory status
- Approved for use in cosmetics in the US and EU, but restricted to low concentrations (typically up to 0.1%) and not allowed in products intended for use on mucous membranes.
- Common uses
- Rinse-off products, Leave-on products, Hair care, Sun care
- Environmental note
- This synthetic compound may persist in the environment; its impact on aquatic life is not fully understood, so it's less eco-friendly than some natural preservatives.
Good to know
- Diiodomethyltolylsulfone is also used in industrial settings as a fungicide, which is why it's sometimes called Amical 48.
- It is not commonly found in natural or organic skincare lines.
Common questions
What is Diiodomethyltolylsulfone in beauty products?
Diiodomethyltolylsulfone is a man-made preservative that stops bacteria, yeast, and mold from growing in your skincare products. It's often used in small amounts to keep formulas fresh and safe to use over time. Because it can cause skin irritation or allergic reactions in some people, it's more common in products that you wash off rather than leave on your skin.
What does Diiodomethyltolylsulfone do in a beauty product?
It works by disrupting the cell walls and metabolic processes of microorganisms, effectively killing or stopping their growth. This helps extend the shelf life of the product and prevents contamination during use.
Is Diiodomethyltolylsulfone safe for most people?
Generally safe at low concentrations in rinse-off products, but poses a moderate risk of skin sensitization. Avoid if you have known allergies to iodine or preservatives.
Who should be careful with Diiodomethyltolylsulfone?
Individuals with very sensitive or reactive skin Anyone with a known allergy to iodinated compounds
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.