What Is C15-35 Isoparaffin/Isoalkylcycloalkanes?
C15-35 Isoparaffin/Isoalkylcycloalkanes is a group of lightweight hydrocarbons that come from refined petroleum. After crude oil is distilled, a middle-weight fraction rich in C15 to C35 carbon chains is separated, further purified and hydrogenated to remove impurities and stabilize the molecules. The result is a clear odorless liquid made of branched chain and ring-shaped hydrocarbons that spread easily on skin.
Mineral oil derivatives like this have been used in cosmetics since the early 1900s because they are stable, affordable and feel silky. As formulas shifted toward lighter textures in the 1980s formulators began favoring isoparaffin blends such as C15-35 Isoparaffin/Isoalkylcycloalkanes for their non-greasy slip and quick absorption.
You will most often spot this ingredient in moisturizers, lotions, primers, liquid foundations, lip balms, makeup removers, hair serums and sheet or cream masks. It helps give these products a smooth glide while leaving a soft conditioning finish.
C15-35 Isoparaffin/Isoalkylcycloalkanes’s Cosmetic Benefits/Uses
This ingredient is valued mainly for its ability to condition the skin and improve product texture.
As a skin conditioning agent it forms a light, breathable layer that reduces moisture loss, leaving skin feeling soft and supple without a heavy or oily after-feel. Its silky slip also helps spread pigments and active ingredients evenly which can enhance the overall performance and sensory appeal of creams, makeup and sunscreens.
Who Can Use C15-35 Isoparaffin/Isoalkylcycloalkanes
C15-35 Isoparaffin/Isoalkylcycloalkanes suits most skin types including normal, dry, combination and mature skin because it feels light yet helps prevent moisture loss. People with very oily or acne-prone skin may want to monitor how their skin responds if the ingredient appears high up the ingredient list since any occlusive film can sometimes trap oil and debris.
The ingredient is petroleum derived and contains no animal materials so it is acceptable for vegans and vegetarians.
Current safety data show no known risks for pregnant or breastfeeding women when the ingredient is used topically in cosmetics. This is not medical advice and anyone who is pregnant or nursing should confirm product choices with a healthcare professional.
C15-35 Isoparaffin/Isoalkylcycloalkanes does not increase photosensitivity and can be used during daytime routines without raising sunburn risk. It is odorless, stable and unlikely to interfere with actives such as retinoids or vitamin C so layering concerns are minimal.
Potential Side Effects/Adverse Reactions
Responses to topical C15-35 Isoparaffin/Isoalkylcycloalkanes vary from person to person. The effects listed below are possible but uncommon when the ingredient is used at standard cosmetic levels.
- Mild transient irritation or redness
- Clogged pores or breakouts in very oily or acne-prone skin
- Contact dermatitis in individuals sensitive to mineral oil derivatives
- Folliculitis if heavy occlusion traps bacteria around hair follicles
If a negative reaction occurs stop using the product and consult a medical professional.
Comedogenic Rating
Rating: 1/5 – Highly refined isoparaffin molecules are too large to seep into pores so they rarely trigger comedones. They sit on the surface forming a thin breathable layer that slows water loss. That said, any occlusive film can trap existing sebum and debris if a formula is very rich or layered heavily, which is why a few oily or acne-prone users may notice congestion. Overall most breakout-prone skin tolerates C15-35 Isoparaffin/Isoalkylcycloalkanes well but should watch how their skin responds. Formula thickness, the presence of other comedogenic ingredients and individual skin chemistry matter more than this ingredient itself.
Summary
C15-35 Isoparaffin/Isoalkylcycloalkanes works as a lightweight skin conditioner that locks in moisture, improves spreadability and leaves a silky finish without a greasy feel. By forming a soft occlusive layer it supports the skin barrier and helps disperse pigments for smoother makeup payoff. Its popularity sits in the middle ground: not as buzz-worthy as botanical oils yet widely used by formulators who value stability affordability and a clean sensory profile. Safety assessments show it to be low-risk, non-sensitizing and non-phototoxic for topical use. As with any new skincare ingredient it is wise to patch test a product first to confirm personal compatibility.