Found in 5,973 products in our database, PEG-40 Hydrogenated Castor Oil is one of the most widely used emulsifiers and solubilisers in cosmetics. Derived from castor oil through ethoxylation and hydrogenation, this ingredient helps oil and water mix seamlessly, dissolves fragrances into water-based formulations, and improves product texture. With a safety rating of 2/10 from SkinSenseDiary and CIR confirmation that it is safe when formulated to be non-irritating, it is a dependable workhorse behind many of the products you use every day.
PEG-40 Hydrogenated Castor Oil is a non-ionic surfactant and emulsifier made by reacting hydrogenated castor oil with ethylene oxide (a process called ethoxylation). The “40” in its name refers to the average number of ethylene oxide units per molecule, which determines its water-solubility and emulsifying power. Hydrogenated castor oil is derived from the seeds of Ricinus communis (castor plant), making this a plant-derived ingredient despite the chemical modification involved in its production.
In cosmetic formulations, PEG-40 Hydrogenated Castor Oil serves primarily as an emulsifier (blending oil and water phases) and a solubiliser (dissolving oil-soluble ingredients such as fragrances, essential oils, and fat-soluble vitamins into water-based products). It is the most widely used PEGylated castor oil in the industry, with 2,107 reported uses in the FDA’s VCRP database and a maximum use concentration range of up to 22% in leave-on hair products. Its trade name Cremophor RH 40 is well known in both the cosmetics and pharmaceutical industries, where it is also used as a drug delivery vehicle.
The CIR Expert Panel has assessed PEG-40 Hydrogenated Castor Oil as part of a group of 130 PEGylated oil ingredients. In the original 1997 assessment, PEG-30 and PEG-40 hydrogenated castor oil were found safe at concentrations up to 100%. The 2012 amended report expanded the group to 130 ingredients and concluded they are all safe in present practices of use and concentration when formulated to be non-irritating. The hydrogenation step makes this ingredient more chemically stable than its non-hydrogenated counterpart by saturating the double bonds in the ricinoleic acid chains, reducing the potential for oxidation.
Helps oil-based and water-based ingredients form a stable, uniform mixture. Without emulsifiers like PEG-40 HCO, creams, lotions, and many serums would separate into distinct oil and water layers. It ensures product consistency from the first to the last use.
Dissolves oil-soluble ingredients — such as fragrances, essential oils, and fat-soluble vitamins (A, D, E, K) — into water-based formulations. This allows clear toners, micellar waters, and aqueous serums to carry ingredients that would otherwise not mix with water.
Improves the feel of products on the skin, contributing to smoother application and a more elegant texture. It helps formulations spread evenly and absorb without leaving a greasy or sticky residue, enhancing the overall user experience.
As a non-ionic surfactant, PEG-40 Hydrogenated Castor Oil provides mild cleansing action that removes dirt and excess oil without stripping the skin’s natural moisture barrier. It is gentler than anionic surfactants like SLS, making it suitable for sensitive skin formulations.
Suitable for: Most skin types, including sensitive skin at typical use concentrations. PEG-40 Hydrogenated Castor Oil is a formulation helper rather than an active ingredient — it works behind the scenes to ensure the product performs well. However, it is not entirely irritation-free: higher concentrations, use around the eye area, or formulations combining it with fragrances may cause mild irritation in some individuals. It is commonly found in cleansers, micellar waters, toners, serums, creams, hair care, and fragrance products.
PEG-40 Hydrogenated Castor Oil receives a low risk rating of 2/10. The CIR Expert Panel concluded it is safe in cosmetics when formulated to be non-irritating, based on extensive toxicological data. It is permitted in the EU without restrictions. In dermal irritation studies, formulations containing up to 20% PEG-40 hydrogenated castor oil showed low irritancy potential under test conditions — though individual responses, product formulation, and application site (e.g. the eye area) can all influence tolerability. There are no allergen flags and no GHS hazard codes in our database. The “Safe with Qualifications” CIR conclusion refers to the requirement that products be formulated to be non-irritating — a standard manufacturing practice.
The “PEG” concern — what the acronym actually means. PEG stands for polyethylene glycol, a polymer made from ethylene oxide. Some consumers worry about PEG ingredients because they associate them with ethylene oxide (a known carcinogen) and 1,4-dioxane (a potential contaminant). In practice, the ethylene oxide is consumed during the reaction and is not expected to be present at significant levels in the final product. However, trace amounts of 1,4-dioxane can remain as a by-product of ethoxylation. The cosmetic industry uses purification steps to reduce these residues, and regulatory bodies (EU, FDA) monitor levels — but “controlled” does not mean “zero.” Modern manufacturing practices keep residual 1,4-dioxane well below established safety thresholds, though the contamination risk is real and is the reason purification is a regulatory expectation, not optional.
Penetration enhancement — a real nuance for combination products. The CIR Panel noted that some PEG ingredients can enhance the penetration of other ingredients through the skin. They cautioned that care should be taken when formulating products that combine PEG-40 Hydrogenated Castor Oil with ingredients whose safety is based on their lack of dermal absorption. This is primarily managed through formulation design, but it means that in products containing potentially irritating actives (such as certain preservatives, fragrances, or exfoliating acids), PEG-40 HCO could increase their penetration and thus their irritation potential. For most standard cosmetic products this is well-controlled, but it is worth being aware of if you have highly reactive skin.
Not the same as castor oil. PEG-40 Hydrogenated Castor Oil is chemically distinct from plain castor oil. The ethoxylation and hydrogenation processes transform it into a water-soluble emulsifier, whereas castor oil is a pure oil. The two have different properties, different functions in formulations, and different skin-feel profiles.
PEG-40 Hydrogenated Castor Oil is generally considered safe for topical use during pregnancy and nursing. As a formulation helper, it has low dermal penetration under normal cosmetic use conditions, though like other PEG ingredients it may facilitate the penetration of other formula components. The CIR review found no reproductive or developmental toxicity concerns for PEGylated castor oils. No regulatory bodies advise against its use in cosmetic products during pregnancy. If you have specific concerns, consult your healthcare provider for personalised guidance.
PEG-40 Hydrogenated Castor Oil works behind the scenes to keep your product stable and well-mixed. It does not target specific skin concerns like wrinkles, acne, or pigmentation. Its job is to ensure the product delivers its active ingredients effectively and feels good on your skin.
In most skincare products, PEG-40 Hydrogenated Castor Oil is used at concentrations well below 10%. At these levels, it performs its emulsifying and solubilising functions without contributing to irritation. Higher concentrations (up to 22%) may appear in specialised hair products.
If a product is a clear liquid that contains fragrance or essential oils (like micellar water or a clear toner), there is a good chance PEG-40 Hydrogenated Castor Oil is the ingredient making that clarity possible. It dissolves the oil-soluble components into the water phase, resulting in a single, transparent product.
Solubilises fragrances and actives into clear water-based solutions. Provides gentle cleansing action without the need for rinsing. A key ingredient in many micellar water formulations.
Acts as the emulsifier that keeps oil and water phases blended. Ensures the product remains smooth and consistent from first to last use, preventing separation over time.
Provides mild surfactant action that removes makeup and impurities without stripping the skin. Commonly found in gentle cleansing gels and foaming washes for sensitive skin.
PEG-40 HCO is one of the most effective solubilisers for incorporating fragrance compounds and essential oils into water-based products, creating clear, stable formulations.
Helps dissolve oil-soluble vitamins into aqueous formulations, improving their delivery and ensuring even distribution throughout the product.
Compatible with most water-soluble active ingredients. PEG-40 HCO enhances formulation stability without interfering with the activity of common skincare actives.
As a non-ionic surfactant, PEG-40 HCO is generally compatible with most surfactant types. However, certain anionic surfactants at high concentrations may affect its solubilising capacity in some formulations.
Extremely acidic conditions (pH below 3) may reduce the emulsifying efficiency of PEG-40 HCO. In standard cosmetic pH ranges (4–7), it performs optimally.
High salt concentrations can affect the cloud point and solubilising behaviour of PEG-40 HCO. This is primarily a formulator concern and does not impact product safety.
Found in 5,973 products in our database. PEG-40 Hydrogenated Castor Oil appears across many product categories — particularly cleansers, micellar waters, creams, serums, and makeup primers. Here are some examples:
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