What Is Myreth-5 Carboxylic Acid?
Myreth-5 Carboxylic Acid is a synthetic ingredient made by attaching about five units of ethylene oxide to a fatty acid chain, then ending the molecule with a carboxylic (acid) group. The fatty part is often sourced from plant oils such as coconut or palm, while the ethylene oxide portion comes from petrochemical feedstocks. This mix of water-loving and oil-loving parts lets the ingredient act as a gentle surface cleaner.
The use of ethoxylated fatty acids in personal care started in the mid-20th century when formulators looked for milder alternatives to traditional soaps. Over time, chemists fine-tuned the number of ethylene oxide units to balance cleaning power with skin feel. The “5” in the name marks the average of five ethylene oxide links, which gives Myreth-5 Carboxylic Acid a light, easy-to-rinse character that suits modern wash-off products.
Manufacturing involves reacting a chosen fatty alcohol with ethylene oxide under controlled heat and pressure, followed by oxidation to introduce the acid group. Strict purification steps remove residues and ensure the final material meets cosmetic safety standards.
You will most often see Myreth-5 Carboxylic Acid in shampoos, facial cleansers, body washes and micellar waters. It may also appear in exfoliating scrubs and bubble baths where mild foam is desired without stripping the skin.
Myreth-5 Carboxylic Acid’s Cosmetic Benefits/Uses
Formulators choose Myreth-5 Carboxylic Acid mainly for its ability to clean without harshness.
Cleansing: The ingredient lowers surface tension so water can mix with oil and dirt, then lifts this mixture away when rinsed. Its balanced structure produces a soft, creamy foam that feels pleasant and leaves skin and hair refreshed yet comfortable.
Who Can Use Myreth-5 Carboxylic Acid
Thanks to its mild cleansing profile Myreth-5 Carboxylic Acid is generally suitable for normal, oily, combination and even sensitive skin. Dry or eczema-prone skin can also tolerate it in most rinse-off formulas because it removes grime without aggressively stripping the skin’s natural lipids. Very reactive or compromised skin, however, may find any surfactant irritating if left on too long so quick rinsing is advised.
The fatty portion of the molecule is often sourced from coconut or palm plants and no animal-derived additives are required during manufacture, making the ingredient compatible with vegan and vegetarian values so long as the finished product as a whole meets cruelty-free standards.
No specific warnings exist for pregnancy or breastfeeding. Current safety assessments classify Myreth-5 Carboxylic Acid as low risk when used at the levels found in personal care products. That said, this is not medical advice and anyone who is pregnant or nursing should show the full product label to a healthcare professional before introducing something new, just to stay on the safe side.
The ingredient does not make skin more sensitive to sunlight and has no known impact on tanning or photo-ageing. It is also free of fragrance, parabens and silicones, factors some shoppers like to avoid for personal preference.
Potential Side Effects/Adverse Reactions
Reactions to topical Myreth-5 Carboxylic Acid depend on the individual. The points below list potential side effects that could occur, although they are uncommon when the ingredient is used correctly in a well-formulated product.
- Mild skin irritation such as redness or a stinging sensation, especially on very sensitive or damaged skin
- Transient dryness or tightness if the formula stays on the skin longer than directed
- Allergic contact dermatitis in rare cases where a person is specifically sensitised to ethoxylated surfactants
- Eye irritation if the cleanser accidentally gets into the eyes before rinsing
If any of these effects occur stop using the product and consult a healthcare professional for personalised guidance.
Comedogenic Rating
Rating: 0–1 (generally considered non-comedogenic). Myreth-5 Carboxylic Acid is a small, water-soluble surfactant that rinses off completely instead of sitting on the skin or building up inside pores, so it is very unlikely to trap oil or dead cells and start a breakout cycle.
That makes the ingredient suitable for acne-prone or congested skin when used in rinse-off products. Because the molecule is washed away quickly, it poses minimal risk of pore blockage compared with leave-on fatty oils or waxes.
One point to note is that the overall formula still matters; heavy creams or poorly rinsing cleansers could raise the pore-clogging potential even if Myreth-5 Carboxylic Acid itself is low risk.
Summary
Myreth-5 Carboxylic Acid is a mild cleansing agent that lifts oil and dirt then rinses clean thanks to its balanced water-loving and oil-loving structure. It creates a soft foam in shampoos facial washes and body washes, helping skin and hair feel fresh without the squeaky dryness harsher surfactants can cause.
While not as famous as household names like sodium laureth sulfate, it remains a quiet workhorse for formulators seeking gentle yet effective cleansing in everyday products.
Current safety reviews rate it low risk at in-formula levels, with irritation appearing only in a small fraction of users who are highly sensitive to surfactants. As with any new skincare ingredient it is wise to perform a simple patch test when trying a product that contains Myreth-5 Carboxylic Acid to make sure your skin is comfortable with it.