What Is Dimethylol Ethylene Thiourea?
Dimethylol Ethylene Thiourea, chemically known as 1,3-bis(Hydroxymethyl)imidazolidine-2-thione, is a synthetic molecule created in laboratories rather than extracted from plants or animals. It belongs to the imidazolidine family of compounds and features two hydroxymethyl groups attached to a sulfur-containing ring. The ingredient has its roots in the textile industry where it was valued for its ability to inhibit microbial growth on fabrics. Formulators later noticed that the same preservative effect could help keep cosmetic products fresh and stable, leading to its crossover into personal care.
Manufacturing begins with ethylene urea, which reacts with formaldehyde in a controlled environment. A sulfur source is introduced to form the thione ring, and the mixture is carefully purified to remove residual reactants. The result is a fine, water-soluble powder that dissolves easily into cosmetic bases.
Today you will most often see Dimethylol Ethylene Thiourea in products designed for hair care. Common examples include deep-conditioning masks, leave-in conditioners, scalp treatments, styling creams and color-protecting formulations. Its antimicrobial action also makes it useful in creams and lotions where extended shelf life is important.
Dimethylol Ethylene Thiourea’s Cosmetic Benefits/Uses
In topical products Dimethylol Ethylene Thiourea serves two primary roles that improve both performance and longevity.
- Antimicrobial: It helps keep formulas free from bacteria, yeast and mold. By stopping microbes before they multiply the ingredient protects the product from spoilage, maintains texture and reduces the risk of skin irritation that can arise when a product becomes contaminated.
- Hair conditioning: It coats the hair shaft, smoothing rough cuticles so strands feel softer and look glossier. This surface conditioning can also make detangling easier, reduce static and enhance overall manageability in both rinse-out and leave-in treatments.
Who Can Use Dimethylol Ethylene Thiourea
Because it is water soluble and non-oily, Dimethylol Ethylene Thiourea is generally suitable for all skin types including oily, combination, normal and dry. Sensitive skin may tolerate it well in properly formulated products, though anyone with a known sensitivity to formaldehyde donors or sulfur-based compounds should be cautious since this ingredient can release trace amounts of formaldehyde during storage.
The compound is fully synthetic and contains no animal derivatives so it is appropriate for vegetarians and vegans.
Current research offers no specific evidence that topical use poses a risk to women who are pregnant or breastfeeding, yet data are limited. This text is not medical advice and expectant or nursing mothers should consult a healthcare professional before introducing any new cosmetic product.
Dimethylol Ethylene Thiourea is not known to cause photosensitivity and does not make skin more vulnerable to sunburn. It also has no bleaching effect on hair color so it can be used in dyed or chemically treated hair without altering shade.
Potential Side Effects/Adverse Reactions
Reactions to topical Dimethylol Ethylene Thiourea differ from person to person. The issues listed below are only potential outcomes and are unlikely for most users when the ingredient is used at the low levels approved for cosmetics.
- Allergic contact dermatitis involving redness itching or rash
- Sensitization after prolonged or repeated exposure leading to future allergic reactions at even low concentrations
- Mild eye irritation if a product accidentally enters the eyes
- Scalp irritation in leave-on hair products if used at concentrations higher than recommended
If you experience any of these reactions stop using the product immediately and seek guidance from a qualified medical professional.
Comedogenic Rating
Rating: 0/5. Dimethylol Ethylene Thiourea is a small, water-soluble molecule with no oily or waxy components that could block pores, so it is considered non-comedogenic. This makes it suitable for people prone to acne or breakouts.
Because the ingredient functions mainly as an antimicrobial preservative and surface conditioner, it sits on the hair shaft or remains dispersed in the water phase of a formula rather than forming heavy films on skin. As a result it is unlikely to contribute to blackheads or clogged pores even in leave-on products.
Summary
Dimethylol Ethylene Thiourea offers two key benefits in cosmetics: it suppresses bacteria, yeast and mold to keep products stable and it smooths hair cuticles for softer, glossier strands and easier detangling. The preservative effect comes from its ability to interfere with microbial cell function while the conditioning effect arises from its slight affinity for keratin that lets it form a thin, smoothing layer along the hair surface.
The ingredient is far from mainstream and is used mainly in specialized hair treatments or formulas that need extra antimicrobial support, so you will not see it as often as more familiar preservatives or conditioners.
When used within the low concentrations allowed by safety guidelines it is generally safe for most people, although rare allergic reactions can occur. As with any new cosmetic, try a patch test first to be on the safe side.