Peg-60 Castor Oil Isostearate: 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-60 Castor Oil Isostearate?

Peg-60 Castor Oil Isostearate is a plant-derived ingredient created by taking castor oil from the seeds of the Ricinus communis plant, attaching roughly 60 units of ethylene oxide to make it water friendly, then esterifying the result with isostearic acid, a branched fatty acid sourced from vegetable oils. This process turns thick, oily castor oil into a versatile liquid that can mix oil and water without losing the gentle feel people expect in modern skincare. Chemists began exploring ethoxylated castor derivatives in the 1950s when the beauty industry needed safer alternatives to soap-based emulsifiers, and Peg-60 Castor Oil Isostearate has remained popular thanks to its mildness and reliable performance.

The manufacturing steps are straightforward: purified castor oil is heated with ethylene oxide under controlled pressure, producing a water-soluble pegylated oil. The intermediate then reacts with isostearic acid to create an ester that offers improved stability and a lighter skin feel. Because the raw materials come from renewable plant sources the final ingredient suits brands looking to highlight naturally sourced technology.

You will typically find Peg-60 Castor Oil Isostearate in facial cleansers, micellar waters, makeup removers, lotions, sunscreens, sheet masks, leave-on hair conditioners and color cosmetics where a smooth, non-greasy texture is essential.

Peg-60 Castor Oil Isostearate’s Cosmetic Benefits/Uses

This ingredient appears on labels mainly for one key reason that benefits almost every type of formulation.

Emulsifying: Peg-60 Castor Oil Isostearate helps oil and water blend into a stable emulsion, allowing creams and lotions to stay uniform from the first pump to the last drop. A good emulsifier prevents separation, improves spreadability and ensures that active ingredients are evenly delivered onto skin or hair, resulting in a smooth, pleasant application without a heavy residue.

Who Can Use Peg-60 Castor Oil Isostearate

This emulsifier is considered gentle enough for most skin types including dry, normal, combination, oily and even sensitive skin because it has a low irritation profile and leaves very little residue. Those with extremely acne-prone skin might prefer lighter alternatives since any rich emollient has a slim chance of feeling heavy on very oily complexions.

Peg-60 Castor Oil Isostearate is sourced entirely from plants, so it is suitable for vegans and vegetarians. No animal-derived raw materials or by-products are involved in its manufacture.

The ingredient is not known to pose special risks for people who are pregnant or breastfeeding and it is classed as safe by global cosmetic regulations. This is not medical advice and anyone expecting or nursing should show the full product ingredient list to a health professional before use to be on the safe side.

Peg-60 Castor Oil Isostearate does not increase photosensitivity so it will not make skin more prone to sunburn. It also rinses cleanly which helps minimize build-up on scalp or skin when used in cleansers and makeup removers.

Potential Side Effects/Adverse Reactions

Reactions to topical Peg-60 Castor Oil Isostearate vary from person to person. The following list covers potential side effects only and most users will not notice any of them when the ingredient is formulated correctly.

  • Mild skin irritation – a small percentage of people may experience temporary redness or stinging, especially on compromised skin
  • Allergic contact dermatitis – rare hypersensitivity to castor oil or PEG derivatives can trigger itching or rash
  • Eye discomfort – if the ingredient enters the eyes it can cause transient watering or stinging until rinsed out
  • Acne flare-up in very oily skin – heavy or layered use in oil-rich routines could occasionally clog pores in those already prone to breakouts
  • Enhanced penetration of other actives – by improving solubility it might let stronger actives absorb a bit faster which could heighten their own irritation potential

If you notice any adverse effect discontinue use and consult a healthcare professional.

Comedogenic Rating

Rating: 2 / 5

Peg-60 Castor Oil Isostearate starts from castor oil, which on its own has a mild tendency to sit on skin, but pegylation and the branched isostearate tail make the molecule more water friendly and easier to rinse. In most formulas it acts as an emulsifier rather than a heavy occlusive, which keeps the pore-clogging risk low though not zero. People who break out easily can usually tolerate it when used in light lotions, cleansers or micellar waters, but very rich leave-on products containing a higher percentage might feel too heavy for extremely oily skin.

The ingredient also helps solubilize oils and makeup so it is more likely to lift residue off skin than add to it when used in rinse-off formats, further reducing clogging potential.

Summary

Peg-60 Castor Oil Isostearate is a plant sourced emulsifier that keeps oil and water blended, improves product spread and leaves a smooth non-greasy finish. It does this by pairing a water loving PEG chain with an oil loving castor-isostearate part, letting it sit at the oil-water interface and stabilize the mix.

While not as famous as some newer bio-based emulsifiers, it remains a quiet workhorse in cleansers, makeup removers, sunscreens and lotions because it is reliable, gentle and easy to formulate.

Safety reviews rate it as low risk with only occasional irritation or pore issues in very oily skin. As with any new skincare product it is smart to do a quick patch test the first time you try something that contains Peg-60 Castor Oil Isostearate.

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