What Is Arachideth-20?
Arachideth-20 is a synthetic, nonionic surfactant made by joining arachidyl alcohol with an average of 20 units of ethylene oxide. Arachidyl alcohol is a fatty alcohol usually sourced from vegetable oils such as peanut, corn or rapeseed. Through a process called ethoxylation, manufacturers react the fatty alcohol with ethylene oxide under heat and pressure, creating a molecule that is both oil loving and water loving. This dual nature allows it to mix oil and water smoothly, which is why it shows up in many modern personal care formulas.
The ingredient entered cosmetic production in the early 1980s when formulators were looking for milder, more versatile alternatives to traditional soaps. Its gentle cleansing profile and reliable ability to stabilize emulsions quickly made it a staple in skin and hair products. Today you can spot Arachideth-20 in facial cleansers, body washes, moisturizers, sunscreens, makeup removers, leave-on creams, sheet masks and even lightweight hair conditioners.
Arachideth-20’s Cosmetic Benefits/Uses
Arachideth-20 brings a couple of key technical perks that translate into a pleasant user experience.
- Cleansing: Acts as a mild surfactant that lifts dirt, excess oil and makeup from skin or hair without leaving a tight feeling, helping create gentle foaming or milk-like rinse-off textures
- Emulsifying: Keeps oil and water phases blended so lotions, creams and serums stay smooth and stable over time, preventing separation while giving formulas a light, non-greasy feel
Who Can Use Arachideth-20
Arachideth-20 is generally well tolerated by most skin types. Its mild surfactant profile makes it suitable for oily, combination, normal and even dry skin because it cleanses without stripping natural moisture. Extremely sensitive or compromised skin may still find any surfactant irritating so patchy redness or tightness could occur in those cases.
The fatty alcohol building block is typically sourced from vegetable oils which means the ingredient is normally plant derived and therefore appropriate for vegan and vegetarian lifestyles. Those following strict vegan guidelines may wish to confirm that the entire supply chain avoids animal processing aids.
No research indicates that topical Arachideth-20 poses risks during pregnancy or while breastfeeding. Because every pregnancy is unique this information is not medical advice and anyone who is pregnant or nursing should run any skincare product past a doctor just to be on the safe side.
The molecule does not make skin more sensitive to the sun so it is not considered photosensitizing. Its gentle nature also allows it to be used in haircare without weighing strands down.
Potential Side Effects/Adverse Reactions
Reactions to Arachideth-20 vary from person to person. The following list covers potential but unlikely side effects when the ingredient is applied topically in a properly formulated product.
- Mild skin irritation such as redness or itching
- Contact dermatitis in individuals with a specific surfactant sensitivity
- Eye stinging or watering if the product accidentally gets into the eyes
- Dryness when used in very high concentrations or in formulas lacking additional moisturizers
If you notice any of these effects stop using the product and consult a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 / 5
Arachideth-20 is considered very low on the pore-clogging scale. Ethoxylation turns the naturally oil-based arachidyl alcohol into a highly water-miscible molecule that rinses away without leaving an occlusive film. Its large molecular size also makes it less likely to penetrate follicles and build up inside pores.
Because of this low rating, the ingredient is generally suitable for people who are prone to acne or breakouts.
Real-world comedogenicity still depends on the overall formula, so a product loaded with heavy oils could counteract Arachideth-20’s low score.
Summary
Arachideth-20 works primarily as a mild cleanser and an emulsifier. Its structure features a fatty alcohol tail that grabs onto oils and a chain of ethylene oxide units that bond with water, allowing it to lift grime while keeping oil-and-water blends stable and silky.
While not the flashiest name on an ingredient list, it is a quiet workhorse found in many cleansers, lotions, sunscreens and hair conditioners because it provides reliable performance at low cost.
Current evidence shows it is safe for most users, with only rare reports of irritation when used in very high amounts. As with any new cosmetic, doing a quick patch test is a smart way to confirm personal compatibility.