Ingredient review
Dimethylol Ethylene Thiourea
INCI: DIMETHYLOL ETHYLENE THIOUREA
An effective but controversial preservative that may cause skin irritation in sensitive individuals.
In plain English
Dimethylol Ethylene Thiourea is a synthetic preservative added to cosmetics to stop bacteria, yeast, and mold from growing. It works by slowly releasing small amounts of formaldehyde over time, which kills microbes. This ingredient is most often found in rinse-off products like shampoos and body washes, and less commonly in leave-on creams or lotions. Because it can release formaldehyde, it may cause irritation or allergic reactions in people with sensitive skin.
Review score
Safety, usefulness, and evidence
Higher-caution ingredient
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
Read the cautions before using
Dimethylol Ethylene Thiourea 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 Dimethylol Ethylene Thiourea.
- 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 that acts as a formaldehyde-releasing preservative in cosmetic formulations.
How it works
It slowly breaks down over time to release trace amounts of formaldehyde, which is a potent antimicrobial agent that prevents spoilage and extends product shelf life.
Pros
Effective preservation
At low concentrations, it reliably prevents microbial growth, keeping products safe to use over time.
Cost-efficient
It is inexpensive for manufacturers, which can help keep product prices lower for consumers.
Cons and cautions
Formaldehyde release
It slowly releases formaldehyde, which can irritate skin and is a known allergen for some people.
Moderate irritation risk
Even at approved levels, it may cause redness, itching, or dermatitis, especially on sensitive or damaged skin.
Best for
- People with normal skin using rinse-off products
- Those who tolerate standard preservatives well
Use caution if
- Individuals with known formaldehyde allergy or sensitive skin
- Anyone seeking a formaldehyde-free cosmetic routine
Usage tips
Safety summary
Dimethylol Ethylene Thiourea is considered safe for most people when used in rinse-off products at regulated concentrations. However, its potential to release formaldehyde means it can cause allergic reactions or irritation in sensitive individuals. It is best avoided by those with known formaldehyde sensitivity.
Research notes
Studies confirm its efficacy as a preservative and its potential as a skin sensitizer due to formaldehyde release. Regulatory bodies have set safe usage limits, but consumer advocacy groups often recommend alternatives for sensitive skin.
Common label clues
- Typical concentration
- Up to 1%
- Regulatory status
- Approved for use in cosmetics in the EU and US at concentrations up to 1%, with restrictions on total formaldehyde release. Always check local regulations.
- Common uses
- Rinse-off products like shampoos and cleansers, Some leave-on formulations
- Environmental note
- As a synthetic compound, its environmental persistence is not well studied, but it is not known to be a major concern at typical usage levels.
Good to know
- Formaldehyde-releasing preservatives are strictly regulated; the amount released is typically below safety limits set by authorities like the SCCS.
- This ingredient is less common in modern 'clean beauty' formulations due to consumer preference for alternative preservatives.
Common questions
What is Dimethylol Ethylene Thiourea in beauty products?
Dimethylol Ethylene Thiourea is a synthetic preservative added to cosmetics to stop bacteria, yeast, and mold from growing. It works by slowly releasing small amounts of formaldehyde over time, which kills microbes. This ingredient is most often found in rinse-off products like shampoos and body washes, and less commonly in leave-on creams or lotions. Because it can release formaldehyde, it may cause irritation or allergic reactions in people with sensitive skin.
What does Dimethylol Ethylene Thiourea do in a beauty product?
It slowly breaks down over time to release trace amounts of formaldehyde, which is a potent antimicrobial agent that prevents spoilage and extends product shelf life.
Is Dimethylol Ethylene Thiourea safe for most people?
Dimethylol Ethylene Thiourea is considered safe for most people when used in rinse-off products at regulated concentrations. However, its potential to release formaldehyde means it can cause allergic reactions or irritation in sensitive individuals. It is best avoided by those with known formaldehyde sensitivity.
Who should be careful with Dimethylol Ethylene Thiourea?
Individuals with known formaldehyde allergy or sensitive skin Anyone seeking a formaldehyde-free cosmetic routine
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.