What Is Myreth-3?
Myreth-3 is a synthetic ingredient classified as a polyoxyethylene ether, built from a fatty alcohol core linked to three ethylene oxide units. The “myreth” part points to its myristyl (14-carbon) alcohol backbone while the “3” tells us there are three ethylene oxide groups attached. This balance of oil-loving and water-loving parts allows Myreth-3 to mix substances that normally stay separate.
The compound was first explored in the mid-20th century when chemists were searching for gentler alternatives to natural soaps. By reacting myristyl alcohol, often sourced from coconut or palm kernel oil, with controlled amounts of ethylene oxide, they produced a range of myreth ingredients. The version with three ethylene oxide units offered a good mix of mildness, stability and performance, and it soon found its way into personal care formulas.
Manufacturing Myreth-3 involves ethoxylation: purified myristyl alcohol is placed in a reactor, then ethylene oxide gas is introduced under heat and pressure. Catalysts help the gas attach to the alcohol in a step-wise fashion until the desired “3” average units are reached. The result is a clear to pale-yellow liquid that blends well with both oils and water.
Today Myreth-3 appears in a wide array of cosmetics. You might spot it in cleansing milks, face masks, moisturizing lotions, light creams, hair conditioners and leave-on serums. Formulators favor it when they need a mild helper that keeps oil and water parts from separating and that also gives products a smooth, non-greasy feel.
Myreth-3’s Cosmetic Benefits/Uses
In formulas Myreth-3 plays one main role that supports texture and stability.
Emulsifying: Myreth-3 helps oil and water blend into a uniform mixture, preventing separation and giving products a consistent look and feel. This leads to creams that stay silky, lotions that spread evenly and cleansers that rinse without leaving a film.
Who Can Use Myreth-3
Thanks to its mild nature Myreth-3 is generally well tolerated by all skin types including oily, dry, combination and even sensitive skin. It does not clog pores or leave a heavy film so acne-prone users usually find it agreeable. The ingredient’s low irritation profile also makes it suitable for mature or sensitized skin.
Myreth-3 is typically produced from plant sources such as coconut or palm kernel oil and contains no animal by-products, so it is ordinarily considered vegan and vegetarian friendly. Anyone following a strict lifestyle should still confirm the sourcing policy of the specific brand.
No studies have flagged Myreth-3 as a concern for women who are pregnant or breastfeeding. It is not absorbed deeply through intact skin and is classified as non-toxic at the levels used in cosmetics. This is not medical advice; expectant or nursing mothers should show any skincare products to their doctor before use to be safe.
The ingredient does not make skin more sensitive to sunlight and has no known impact on photosensitivity.
Potential Side Effects/Adverse Reactions
Reactions to topical Myreth-3 differ from person to person. The effects listed below are only possibilities and, when the ingredient is used correctly in a finished product, most people will not experience them.
- Mild skin irritation such as itching or stinging, more likely if the formula contains a high concentration
- Redness or transient flushing on very sensitive skin
- Allergic contact dermatitis in rare cases for individuals with specific sensitivities
- Eye irritation or watering if the product accidentally gets into the eyes
- Increased penetration of other actives, which could amplify the effects of stronger ingredients present in the same formula
If any of these reactions occur stop use immediately and consult a healthcare professional or dermatologist
Comedogenic Rating
Rating: 1/5
Myreth-3 is a lightweight emulsifier that sits on the surface only long enough to blend oil and water then either remains in a thin, non-film-forming layer or is rinsed away. It lacks the heavy waxes and thick oils that typically block pores, so its tendency to trigger comedones is very low. People prone to acne can usually use products containing Myreth-3 without worrying about extra breakouts. Because it can boost the penetration of other ingredients, any pore-clogging substances paired with it could have a slightly stronger effect, but this is more about the accompanying actives than Myreth-3 itself.
Summary
Myreth-3 is an emulsifier that keeps oil and water mixed, gives formulas a smooth easy-spread texture and supports overall product stability. It does this by using its balanced fat-loving and water-loving parts to sit at the boundary between the two phases and hold them together.
While not a headline ingredient, Myreth-3 is quietly popular among formulators who need a mild helper that does its job without fuss. You will often find it in cleansers, lotions and lightweight creams where a non-greasy feel is desired.
Current safety data classifies Myreth-3 as low risk with minimal irritation potential and virtually no comedogenicity. As with any cosmetic ingredient it is smart to perform a quick patch test when trying a new product to ensure your skin agrees with the full formula.