Peg-15 Castor Oil: 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: July 1, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Peg-15 Castor Oil?

Peg-15 Castor Oil starts with castor oil, a thick vegetable oil pressed from the seeds of the castor bean plant. Chemists react this oil with about fifteen units of ethylene oxide, a process that links small water-loving pieces onto the original oil. The result is an ingredient that can mix with both water and oil, something plain castor oil cannot do well. This tweak happened in the mid-20th century when formulators looked for gentler ways to clean skin and blend oily and watery parts of creams without using harsh soaps.

The production is straightforward: purified castor oil is placed in a controlled reactor, ethylene oxide gas is added, the mixture is kept at set pressure and temperature, then the finished liquid is filtered and tested for purity. The average of fifteen added units keeps the texture light enough to pour yet thick enough to anchor other ingredients in place.

Because it can handle both oil and water, Peg-15 Castor Oil shows up in many topical products. You will see it in facial cleansers, micellar waters, gentle makeup removers, sheet mask essences, lightweight lotions, scalp treatments and some color cosmetics like liquid foundation where even coverage matters.

Peg-15 Castor Oil’s Cosmetic Benefits/Uses

This ingredient earns its spot on an ingredient list by doing more than one job at a time

  • Cleansing: Its dual nature grabs onto dirt and makeup while staying mild on skin, helping formulas rinse away grime without stripping natural moisture
  • Emulsifying: It holds oil and water together so creams stay smooth and stable, preventing separation in the jar and giving the final product a pleasant, even feel during use

Who Can Use Peg-15 Castor Oil

This ingredient suits nearly every skin type. Its mild cleansing action is gentle enough for dry or sensitive skin while its ability to lift oil makes it welcome in oily or combination routines. The only group that may want to steer clear are people with a known allergy to castor derivatives because even the ethoxylated form can trigger the same reaction.

Peg-15 Castor Oil is plant derived, coming from castor beans, and contains no animal by products, so it aligns with vegan and vegetarian values.

No studies link the topical use of this ingredient to problems in pregnancy or while breastfeeding. Absorption through intact skin is minimal, yet this is not medical advice and anyone expecting or nursing should run any skincare product by a qualified health professional just to be safe.

The molecule does not cause photosensitivity, so it will not make skin more prone to sunburn. Routine daytime sun protection is still important for overall skin health.

Because it works in a variety of formulas, Peg-15 Castor Oil can be used daily and pairs well with most other skincare actives.

Potential Side Effects/Adverse Reactions

Reactions to topical Peg-15 Castor Oil vary from person to person. The points below list potential side effects that could occur even though they are uncommon when the ingredient is used correctly in a finished product.

  • Mild skin irritation a temporary feeling of stinging or burning, often on very sensitive or compromised skin
  • Allergic contact dermatitis redness, itching or rash in individuals allergic to castor oil or its derivatives
  • Eye irritation watering or stinging if the product accidentally gets into the eyes
  • Follicular clogging a rare issue in those extremely prone to comedones when high concentrations are left on the skin
  • Contaminant sensitivity irritation triggered by trace residues of processing agents if purification standards are not met

If any negative reaction occurs stop using the product and seek advice from a healthcare professional.

Comedogenic Rating

Rating: 1 out of 5

Peg-15 Castor Oil is highly water soluble thanks to its ethoxylated side chains, so it rinses off the skin more easily than raw castor oil and is less likely to sit in pores. Laboratory data and formulator feedback show a very low rate of pore blockage, which is why it earns a near non-comedogenic score of 1. It is generally suitable for people who are prone to acne or breakouts.

Formulas that suspend high levels of heavy oils alongside Peg-15 Castor Oil could still feel rich on the skin, so the finished product, not the helper ingredient itself, determines final clogging potential.

Summary

Peg-15 Castor Oil serves two main jobs: it acts as a gentle cleanser by surrounding oil and dirt so they rinse away with water, and it works as an emulsifier that keeps watery and oily parts of a formula blended into a stable, smooth mixture. It does this because its castor-oil backbone loves lipids while its attached polyethylene glycol chains love water, making it an effective bridge between the two.

You will not see social media buzz about Peg-15 Castor Oil, yet it quietly appears in many mainstream cleansers, micellar waters, lotions and hair treatments where stable texture and mild cleansing are priorities. Chemists appreciate its reliability even if shoppers rarely notice it.

Current research and decades of use point to a strong safety profile with low irritation and almost zero systemic absorption. As with any new cosmetic ingredient it is smart to patch test a product before full-face use just to be sure your skin agrees with it.

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