What Is Peg-18 Castor Oil Dioleate?
Peg-18 Castor Oil Dioleate is a plant-derived ingredient made from castor oil that has been chemically linked with about 18 units of ethylene oxide and then reacted with oleic acid to form diesters. The result is a silky liquid that mixes well with both oil and water, making it a useful helper in modern skin and hair formulas.
Castor oil itself has a long history in personal care, but its sticky texture and limited solubility pushed chemists in the mid-1900s to look for gentler, more versatile versions. By attaching polyethylene glycol (PEG) chains and oleic acid, they created Peg-18 Castor Oil Dioleate, a nonionic molecule that is easier to formulate and less greasy than raw castor oil.
Production starts with pure castor oil pressed from Ricinus communis seeds. The oil is treated with ethylene oxide in a controlled setting to add the PEG groups, then oleic acid is introduced to form the dioleate esters. Careful purification removes unreacted material, leaving a clear to pale yellow liquid that meets cosmetic safety standards.
Because it excels at keeping oil and water together, you will often see Peg-18 Castor Oil Dioleate in creams, lotions, makeup removers, cleansing balms, hair conditioners, sunscreens, sheet masks and leave-on treatments where a smooth stable texture is critical.
Peg-18 Castor Oil Dioleate’s Cosmetic Benefits/Uses
This ingredient serves one main purpose in a formula, but that single job delivers several real-world benefits.
Emulsifying: Peg-18 Castor Oil Dioleate helps oil and water blend into a uniform emulsion so products stay mixed on the shelf and spread evenly on skin or hair. A reliable emulsion feels lighter, absorbs better and ensures active ingredients are delivered consistently with each use.
Who Can Use Peg-18 Castor Oil Dioleate
Because Peg-18 Castor Oil Dioleate is lightweight and non-greasy it generally works for all skin types including dry, oily, combination and sensitive skin. People with very reactive or allergy-prone skin should still scan the full ingredient list to be sure they do not have a known sensitivity to polyethylene glycols or castor derivatives.
The ingredient is produced from castor beans and synthetic ethylene oxide with no animal-derived components, so it is suitable for vegans and vegetarians.
No data suggest that Peg-18 Castor Oil Dioleate poses specific risks in pregnancy or while breastfeeding. This is not medical advice and anyone who is pregnant or nursing should show new products to their healthcare professional before adding them to a routine.
The molecule does not absorb UV light and is not known to increase photosensitivity, so daytime use alongside sunscreen is fine.
Potential Side Effects/Adverse Reactions
Individual reactions to topical Peg-18 Castor Oil Dioleate can vary. The effects listed below are possible but uncommon when the ingredient is used at the concentrations normally found in cosmetics.
- Mild skin irritation – a small percentage of users may notice redness stinging or itching, especially on compromised skin barriers
- Contact allergy – rare cases of allergic dermatitis have been reported in people sensitive to castor oil derivatives or PEG compounds
- Eye irritation – if a product containing high levels of the ingredient accidentally gets into the eyes it can cause temporary discomfort or watering
- Folliculitis in very acne-prone skin – although the ingredient is generally non-comedogenic some highly acneic individuals may experience clogged follicles if a formula is overly rich
If you experience persistent irritation or any other adverse reaction stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1/5
Peg-18 Castor Oil Dioleate is largely water-soluble and used in small amounts so it does not create the heavy film that typically leads to clogged pores. The fatty acid pieces are tethered to a sizable PEG backbone which keeps the molecule light and easy to rinse away. That combination puts it at the low end of the comedogenic scale.
Most acne-prone users can tolerate this emulsifier without extra breakouts, but extremely reactive or oil-heavy skin may still want to watch how the full formula feels.
Keep in mind that the overall product matters. A thick ointment packed with waxes could block pores even if the emulsifier itself is mild.
Summary
Peg-18 Castor Oil Dioleate works as a dependable emulsifier that lets oil and water stay blended, giving creams, cleansers and hair products a smooth stable texture. The PEG side grabs water, the castor and oleic sides grab oil and together they lock the mix in place.
While it is not a buzzword ingredient, formulators value its versatility and silky slip so it quietly powers a wide range of mainstream products.
Safety reviews label it low risk with only isolated reports of irritation or allergy, and its comedogenic rating is low. Still, trying a small patch first is the easiest way to confirm your own skin agrees with any new product.