What Is Isopropyl Hydroxystearate?
Isopropyl Hydroxystearate is an ester formed by linking 12-hydroxy stearic acid, a fatty acid commonly derived from castor oil, with isopropyl alcohol. The result is a waxy liquid that behaves much like natural skin oils. First developed in the mid-20th century as chemists searched for lighter alternatives to heavy mineral oils, it quickly found favor in personal care labs for its smooth feel and skin-friendly profile.
Production begins with the hydrogenation of castor oil to obtain 12-hydroxy stearic acid. This acid is then reacted with isopropyl alcohol in a controlled environment, producing the ester and water as a by-product. After purification, the ingredient is ready for cosmetic use.
You will most often see Isopropyl Hydroxystearate in moisturizers, anti-aging creams, cleansing balms, makeup primers, lipsticks and hair conditioners. Its lightweight texture and high spreadability make it suitable for both leave-on and rinse-off formulas where a soft, non-greasy finish is desired.
Isopropyl Hydroxystearate’s Cosmetic Benefits/Uses
This ingredient is valued for the comfortable feel it gives to products and the way it supports skin softness.
- Skin conditioning – helps maintain skin suppleness by forming a light protective film that reduces water loss, leaving skin feeling smooth and refreshed
- Emollient – fills in the tiny gaps between dead skin cells so the surface feels softer and looks more even, improving the glide and spread of creams and makeup
Who Can Use Isopropyl Hydroxystearate
Its lightweight emollient profile makes Isopropyl Hydroxystearate suitable for most skin types including dry, normal and combination skin. Oily and acne-prone complexions may also tolerate it thanks to its non-greasy slip, yet those who clog easily should watch how their skin responds because richer fatty esters can sometimes sit on the surface and contribute to congestion in very oil-sensitive individuals.
The ingredient is produced from castor oil and isopropyl alcohol, both plant or petrochemical sources, with no animal-derived components. That means products using it are usually appropriate for vegans and vegetarians, although anyone following a strict lifestyle should still check the overall formula and brand sourcing policies.
No data indicates inherent risks for women who are pregnant or breastfeeding when this ester is used topically in cosmetics. That said this is not medical advice and anyone expecting or nursing should review all personal care products with a qualified healthcare provider to be extra sure.
Isopropyl Hydroxystearate does not make skin more sensitive to sunlight and can be worn day or night without changing sun protection habits. It plays well with common actives like retinoids, vitamin C and exfoliating acids because it is chemically stable and non-reactive.
Potential Side Effects/Adverse Reactions
Sensitivity to topical ingredients varies by individual. The effects listed below are potential outcomes that have been reported in rare cases. When the ingredient is used at typical cosmetic levels most people will not notice any negatives.
- Mild skin irritation – transient redness or itching in those with very reactive skin
- Contact dermatitis – uncommon allergic response resulting in persistent rash or swelling
- Pore clogging – possible formation of blackheads or breakouts in users highly prone to comedones, especially if layered with other heavy products
- Eye irritation – stinging or watering if a product containing the ester accidentally gets into the eyes
If any of these reactions occur discontinue use and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 3/5. Isopropyl Hydroxystearate is a mid-weight fatty ester. Its molecular structure lets it sit on the skin surface longer than very light silicones or dry esters yet it is not as heavy as classics like isopropyl myristate. That balance means it can occlude pores in some users but not as aggressively as the highest-ranking offenders. Acne-prone individuals may be able to use it if the overall formula is well balanced and rinses clean, though very breakout-sensitive skin should proceed with caution.
Formulas that pair this ester with mattifying powders or fast-evaporating solvents often feel lighter and reduce the clogging risk. Using it in rinse-off products (cleansers, masks) also minimizes residue on the skin.
Summary
Isopropyl Hydroxystearate conditions skin and acts as an emollient by forming a smooth, breathable film that traps moisture and fills tiny surface gaps so products glide easily. It earns its place in moisturizers, primers and lipsticks because it delivers softness without an oily after-feel.
The ingredient enjoys moderate popularity. It is not as ubiquitous as glycerin or dimethicone but is a steady pick for formulators who want a plant-derived alternative to heavier esters.
Overall safety data show a low rate of irritation or allergy at normal use levels. As with any new cosmetic ingredient it is wise to patch test a product first to be certain your skin agrees with it.