Peg-5 Hydrogenated 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-5 Hydrogenated Castor Oil?

Peg-5 Hydrogenated Castor Oil is a plant-derived ingredient that starts its life as pure castor oil pressed from the seeds of the Ricinus communis plant. The oil is first hydrogenated, a process that adds hydrogen atoms to stabilize the fatty acids and turn the once-liquid oil into a waxy solid. It is then ethoxylated with an average of five units of ethylene oxide, which gives the material the “PEG-5” part of its name and makes it water-soluble. The final result is a gentle, skin-friendly substance that can mix oil and water with ease.

Chemists began experimenting with castor oil modifications in the mid-20th century when the beauty industry was looking for plant-based alternatives to animal fats and harsh detergents. Hydrogenated and PEG-modified castor oils quickly proved useful for their mildness and versatility, so they found a place in lotions, creams and cleansers. Today Peg-5 Hydrogenated Castor Oil is valued in everything from facial masks and micellar waters to makeup removers, sunscreens and anti-aging serums.

The ingredient is produced in carefully controlled steps. After cold-pressing the seeds, the crude castor oil is filtered then subjected to catalytic hydrogenation that saturates the double bonds, improving stability. The hydrogenated oil is then reacted with ethylene oxide gas under pressure, attaching about five ethylene oxide units per triglyceride. Each batch is refined and tested for purity before being shipped to cosmetic labs where formulators add it to water-based or oil-based products that need a mild helper to keep the mix uniform.

Because of its dual affinity for oil and water, Peg-5 Hydrogenated Castor Oil can be found in cleansers, toners, leave-on conditioners, hair styling creams, bath oils and even color cosmetics like liquid foundations. Its presence helps the product spread smoothly, rinse off cleanly and stay stable on the shelf.

Peg-5 Hydrogenated Castor Oil’s Cosmetic Benefits/Uses

This multitasking ingredient supports a formula in two main ways

  • Cleansing: Its amphiphilic structure loosens makeup, sunscreen and excess sebum then allows the debris to be rinsed away with water, leaving skin comfortable and not stripped of moisture
  • Emulsifying: It works as a “bridge” between oil and water phases so lotions, creams and serums stay smooth and consistent without separating during use or storage

Who Can Use Peg-5 Hydrogenated Castor Oil

Because it is gentle and water-soluble Peg-5 Hydrogenated Castor Oil suits most skin types including dry, normal, combination and even many sensitive skins. Its lightweight cleansing action makes it useful for oily skin too though people who are extremely acne-prone may prefer to monitor how their skin reacts since any oil-derived ingredient has a small chance of feeling too rich for them.

The ingredient is sourced from castor beans and modified through hydrogenation and ethoxylation so no animal materials enter the process. This makes it appropriate for both vegetarians and vegans.

No research has flagged Peg-5 Hydrogenated Castor Oil as a concern for women who are pregnant or breastfeeding when used in rinse-off or leave-on cosmetics. That said this is not medical advice and anyone expecting or nursing should show the full ingredient list of their products to a qualified healthcare provider before use just to be safe.

The molecule does not increase the skin’s sensitivity to sunlight and there is no evidence that it interferes with common actives such as retinoids or vitamin C so it pairs well with most daily routines.

Potential Side Effects/Adverse Reactions

Responses to any cosmetic ingredient can differ from person to person. The issues listed below are merely potential outcomes and they are unlikely for the average user when the product is properly formulated.

  • Mild skin irritation such as redness or itching, usually in very sensitive individuals
  • Allergic contact dermatitis in people with a specific castor oil allergy, a rare occurrence
  • Temporary stinging if the raw ingredient or a high-percentage product gets into the eyes
  • Clogged pores or blemishes in users who are highly prone to comedones

If any of these reactions occur stop using the product and seek guidance from a healthcare professional.

Comedogenic Rating

Rating: 1 out of 5

Peg-5 Hydrogenated Castor Oil is highly water-soluble and rinses off easily so it is far less likely to sit in pores compared with raw or highly fatty oils. The hydrogenation step removes reactive double bonds and the PEG units make the molecule bulky and slippery, both of which help it glide off the skin rather than stay behind and clog. For most people, including those with oily or combination skin, this low score means it should not trigger breakouts, though very acne-prone users may still prefer lighter formulas.

Formulation style matters too. In a thin micellar water or foaming cleanser its residue is almost zero while in a rich cream the overall blend of oils and butters can raise the clogging potential. Always look at the full ingredient list if you are worried about congestion.

Summary

Peg-5 Hydrogenated Castor Oil acts as a gentle cleanser and reliable emulsifier. Its oil-loving castor backbone grabs makeup, sunscreen and excess sebum while its water-loving PEG chain lets everything rinse away clean. Those same dual qualities keep oil and water phases locked together so lotions and creams stay smooth and stable on the shelf.

It is a quiet workhorse rather than a headline act. You will spot it in a fair number of face washes, micellar waters, sunscreens and lightweight creams but it rarely makes the marketing front panel.

Safety data show it is low irritation, non-sensitizing for most users and vegan friendly. As with any new product a simple patch test is smart practice in case your skin has unique sensitivities.

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