What Is Hydroxyethyl Methylthiopropenamide?
Hydroxyethyl Methylthiopropenamide is a lab crafted compound that belongs to a small family of sulfur containing amides. You might see it listed on labels as Entadamide A or Hydroxyethyl Methylthioacrylamide. In simple terms it is a clear, water soluble ingredient designed to sit on the surface of skin and form a thin, comfortable shield.
The molecule is built from a propene backbone that carries a sulfur based side group and a hydroxyethyl arm. Chemists start with acrylic acid, attach a methylthio group, then add ethanolamine to introduce the hydroxy part. Each step happens under controlled heat and pH to keep the double bond in the safer Z-configuration, which helps the ingredient spread evenly when applied.
Although its roots lie in pharmaceutical research during the 1990s, formulators soon noticed its gentle film forming skill. By the early 2000s Korean and Japanese beauty brands began adding it to sheet masks to help lock in moisture. Today you will find Hydroxyethyl Methylthiopropenamide in hydrating gels, overnight creams, post peel calming serums, eye masks and even some daily moisturizers aimed at urban pollution defense.
Hydroxyethyl Methylthiopropenamide’s Cosmetic Benefits/Uses
This ingredient is prized for its skin protecting ability. Once applied it forms a breathable layer that helps shield skin from everyday stress like wind, dust and drying indoor air. The light film slows water loss so skin stays hydrated longer, which can make fine lines look softer and give the complexion a fresher appearance. Because the layer is flexible and transparent it will not pill under makeup or feel heavy, making it suitable for both day and night formulas.
Who Can Use Hydroxyethyl Methylthiopropenamide
Most skin types can benefit from Hydroxyethyl Methylthiopropenamide. The lightweight film it creates works well on dry or dehydrated skin by sealing in water, while its non greasy feel keeps it comfortable for normal and combination types. Oily complexions usually tolerate it since the molecule is water soluble and does not clog pores. Sensitive skin also tends to do fine because it is free of fragrance and known irritants, though anyone with a confirmed sulfur allergy should approach with caution.
The compound is produced entirely in the lab without animal-derived substrates so it is suitable for vegans and vegetarians.
No data indicate that the ingredient penetrates deeply enough to pose a risk to women who are pregnant or breastfeeding. That said this is not medical advice and anyone expecting or nursing should show the full ingredient list of any product to their healthcare provider before using it just to be safe.
Hydroxyethyl Methylthiopropenamide does not make skin more sensitive to sunlight. Regular SPF use is still encouraged as part of a daily routine but there is no need for extra precautions beyond standard sun care.
Potential Side Effects/Adverse Reactions
Responses to topical Hydroxyethyl Methylthiopropenamide can differ from one person to the next. The following are potential side effects only. When the ingredient is formulated and used correctly most people will not notice any of these issues.
- Mild transient stinging particularly on freshly exfoliated or compromised skin
- Temporary redness in very sensitive individuals
- Localized itching if a person has an intolerance to sulfur containing compounds
- Contact dermatitis in rare cases of true allergy
- Minor breakouts for those who are extremely acne prone when the product is layered with heavy occlusives
If you experience any of these reactions stop using the product and consult a dermatologist or healthcare professional for guidance.
Comedogenic Rating
Rating: 1/5
Hydroxyethyl Methylthiopropenamide is highly water soluble and does not add oil to the skin so the likelihood of it blocking pores is very low. The thin breathable film it leaves behind is flexible and gets rinsed away easily with regular cleansing. It earns a 1 instead of 0 because any film former can theoretically trap sebum if layered under very heavy occlusive products.
This low score means the ingredient is generally suitable for people prone to acne or breakouts.
As with any film forming agent pairing it with light non occlusive moisturizers will further reduce the chance of congestion.
Summary
Hydroxyethyl Methylthiopropenamide acts mainly as a skin protecting film former. Once applied it creates a sheer comfortable layer that shields against environmental stress and slows moisture loss which helps skin stay hydrated and look smoother.
While it has been a quiet staple in several Korean and Japanese formulas for two decades it remains relatively niche in Western markets. Its inclusion is growing in hydrating serums and pollution defense creams as brands search for lightweight alternatives to silicones.
Current research and in market use suggest it is safe for most skin types with only rare reports of irritation or allergy. As with any new cosmetic ingredient a short patch test is a smart practice before full face application especially for sensitive or reactive skin.