What Is Ricinoleth-40?
Ricinoleth-40 is an ethoxylated version of castor oil, created by attaching roughly forty units of ethylene oxide to the naturally occurring fatty acid ricinoleic acid. This tweak turns a thick plant oil into a water-compatible liquid that can blend oil and water ingredients with ease. The base material comes from the seeds of the castor plant, a hardy crop grown in tropical and subtropical regions.
Castor oil itself has a long history in personal care, valued for its rich texture and glossy finish. Chemists started modifying it in the mid-1900s to improve its solubility and rinsability, which is how Ricinoleth-40 entered cosmetic labs. By adding ethylene oxide, they produced a mild yet effective surfactant that quickly found a home in modern rinse-off and leave-on formulas.
The manufacturing process is straightforward: purified castor oil is placed in a pressure-controlled reactor, ethylene oxide gas is introduced, and the mixture is gently heated. The number 40 reflects the average count of ethylene oxide units that bond to each molecule, giving predictable performance from batch to batch.
Today you will spot Ricinoleth-40 in facial cleansers, micellar waters, makeup removers, shampoos, creamy body washes, sheet masks, lightweight lotions, anti-aging serums, hair conditioners and even some sun care products. Its ability to lift grime while keeping formulas stable makes it popular in both mass-market and prestige lines.
Ricinoleth-40’s Cosmetic Benefits/Uses
Formulators rely on Ricinoleth-40 for more than one job, which is why it appears on many ingredient lists.
- Cleansing – Acts as a gentle surfactant that loosens dirt, excess oil and makeup so they can be rinsed away without stripping skin or hair
- Emulsifying – Keeps oil and water parts of a formula evenly blended, preventing separation and giving products a smooth consistent texture
Who Can Use Ricinoleth-40
Thanks to its gentle nature Ricinoleth-40 is generally well tolerated by most skin types including dry, oily, combination and sensitive skin. It does not leave a heavy residue or clog pores which makes it a fit for acne-prone complexions as well. People with extremely reactive or eczema-prone skin may still want to keep an eye on how their skin feels because any surfactant, even a mild one, can occasionally over-cleanse delicate barriers.
The ingredient is sourced from castor beans and contains no animal derivatives so it is considered suitable for vegans and vegetarians. Brands that carry vegan certifications often list Ricinoleth-40 without restriction.
Current safety reviews show no specific hazards for pregnancy or breastfeeding when Ricinoleth-40 is used in cosmetics at normal concentrations. That said this information is not medical advice and anyone who is pregnant or nursing should have a quick chat with their doctor before starting a new product just to be safe.
Ricinoleth-40 is not known to cause photosensitivity so it will not increase your risk of sunburn. It also plays nicely with common active ingredients such as retinoids and vitamin C since it is primarily a helper ingredient rather than a powerful treatment on its own.
Potential Side Effects/Adverse Reactions
Individual responses to Ricinoleth-40 can vary. The points below outline potential side effects but most people will not encounter them when the ingredient is used at the levels found in finished cosmetics.
- Mild skin irritation such as redness or stinging, especially in very sensitive or already compromised skin
- Contact dermatitis triggered by an allergy to castor derivatives or the ethoxylation process
- Temporary eye irritation if a cleanser or makeup remover containing Ricinoleth-40 gets into the eyes
- In rare cases exaggerated dryness or tightness if used in a formula with a high overall surfactant load
If any discomfort or persistent reaction occurs stop using the product and seek guidance from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 out of 5 (low)
Ricinoleth-40 is highly water soluble and rinses away instead of sitting on the skin so its pore-clogging potential is minimal. Although it starts as castor oil the ethoxylation step removes the heavy oily feel that could trap debris and lead to bumps.
Suitable for acne prone or breakout prone skin because it is unlikely to spark new comedones
If a product contains large amounts of waxes or thick emollients alongside Ricinoleth-40 the overall formula, not this ingredient, might feel heavier and could raise clogging concerns.
Summary
Ricinoleth-40 works as a mild cleanser and dependable emulsifier. Its castor-derived tail grabs oils and impurities while its ethoxylated head loves water, allowing dirt to lift away and keeping oil-water mixes uniform.
It is not a headline ingredient yet it quietly supports a broad range of cleansers, micellar waters, shampoos and light lotions across mass and professional lines because it is plant sourced, versatile and budget friendly.
Safety reviews rate it as low risk with only isolated reports of irritation. Most users tolerate it well, though a quick patch test when trying any new product remains a smart habit.