Arachideth-42: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 23, 2025
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All information on this page is verified using The Personal Care Products Council's (PCPC) INCI database. Our ingredient analyses are based exclusively on PCPC's technical data to ensure accuracy and reliability.

What Is Arachideth-42?

Arachideth-42 is a man-made ingredient created by attaching about 42 units of ethylene oxide to arachidyl alcohol, a fatty alcohol that usually comes from peanut or other vegetable oils. The result is a waxy, water-soluble compound that bridges the gap between oil and water in cosmetic formulas.

Polyethylene glycol (PEG) ethers like Arachideth-42 began showing up in personal care products in the 1950s when formulators wanted safer, more skin-friendly alternatives to harsh soaps. Over the decades its reliable performance and mildness helped it become a staple in modern skin and hair care.

The manufacturing process starts with purified arachidyl alcohol. This fatty alcohol is reacted with ethylene oxide under controlled heat and pressure, producing a chain of repeating PEG units. The average of 42 units is carefully monitored to give the final material its balance of richness and water compatibility.

You will commonly spot Arachideth-42 in facial cleansers, makeup removers, creamy body washes, leave-on lotions, conditioning hair masks, styling creams and even some mild baby care products where gentle cleansing and stable textures are essential.

Arachideth-42’s Cosmetic Benefits/Uses

The beauty industry values Arachideth-42 for a couple of hard-working roles that boost both product performance and user experience.

  • Cleansing: Its amphiphilic nature lets it surround dirt, excess oil and makeup so they rinse away easily with water. Because it is milder than traditional detergents it helps create formulas that clean without leaving skin or hair feeling stripped.
  • Emulsifying: By binding oil and water phases together it stabilises creams, lotions and masks. This keeps products from separating on the shelf, gives them a smooth feel and ensures each use delivers uniform active ingredients and moisture.
Who Can Use Arachideth-42

Thanks to its mild nature Arachideth-42 is generally well tolerated by most skin types including dry, oily and combination skin. Even sensitive complexions usually get along with it because it is less harsh than many traditional surfactants. Those with very reactive or allergy-prone skin may still want to keep an eye on how their skin responds since any ingredient can be a trigger for certain individuals.

The raw material is typically sourced from plant oils so products using a vegetable-derived supply chain are suitable for vegans and vegetarians. If you follow a strict lifestyle check the full ingredient list for animal-derived additives elsewhere in the formula to be sure.

Current research shows no specific pregnancy or breastfeeding warnings tied to topical use of Arachideth-42 in cosmetic amounts. This is not medical advice and anyone who is pregnant or nursing should run new products past a healthcare professional just to be safe.

Arachideth-42 is not known to cause photosensitivity so it will not make skin more prone to sunburn. Standard daytime sun protection is still important for overall skin health.

Potential Side Effects/Adverse Reactions

Responses to any cosmetic ingredient can vary from person to person. The points below outline potential side effects yet most users will never experience them when the ingredient is properly formulated and used as intended.

  • Mild skin irritation
  • Redness or itching on very sensitive skin
  • Rare allergic contact dermatitis
  • Stinging if applied to broken or compromised skin
  • Increased penetration of other ingredients when the skin barrier is damaged

If you notice any of these reactions discontinue use and consult a healthcare professional.

Comedogenic Rating

Rating: 1/5

Arachideth-42 is a large water-soluble molecule whose long PEG chain keeps it from hanging out in pores. The fatty part lifts oil while the hydrophilic chain helps it rinse clean so it rarely forms a film that could trap dead cells or sebum. For that reason it is considered very low on the clogging scale.

Most people prone to acne or breakouts can use products containing Arachideth-42 without extra worry.

Keep in mind that overall formula counts. If the product also contains rich oils or waxes the blend, not Arachideth-42 itself, could still feel heavy on very oily skin.

Summary

Arachideth-42 is valued for two jobs: gentle cleansing and dependable emulsifying. Its oil-loving end grabs grime while the water-loving PEG side lets it wash away so skin and hair feel clean yet soft. The same split personality also holds oil and water together giving creams and lotions a smooth even texture.

It is a behind-the-scenes helper found in many everyday cleansers body washes and conditioning masks rather than a flashy headline ingredient.

With decades of safe use and low irritation reports it is regarded as a skin-friendly choice. Still, try a quick patch test when you bring home any new product that contains it just to be sure your skin stays happy.

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