What Is Isotridecyl Isononanoate?
Isotridecyl Isononanoate, also listed on labels as Isotridecyl 3,5,5-trimethylhexanoate, is an ester created by joining a branched chain fatty alcohol (isotridecyl alcohol) with a short chain fatty acid (isononanoic acid). This pairing gives the molecule a lightweight oily feel that spreads easily on skin without feeling greasy.
The ingredient was first introduced in the late 1990s when formulators were searching for alternatives to heavy plant oils and mineral oil. By tweaking the length and branching of the alcohol and acid, chemists produced an ester that mimics the softness of natural skin lipids yet stays stable in a wide range of formulations.
Manufacturing begins with bio-based or synthetic isotridecyl alcohol produced through oxo synthesis of propylene. This alcohol is then reacted with isononanoic acid under controlled heat and pressure. The result is a clear, colorless liquid ester that resists oxidation and holds up well to high temperatures, making it a reliable ingredient for modern cosmetics.
You can spot Isotridecyl Isononanoate in facial moisturizers, body lotions, sunscreens, makeup primers, creamy foundations, hair serums, sheet masks and anti-aging formulas where a silky finish is desired.
Isotridecyl Isononanoate’s Cosmetic Benefits/Uses
Formulators prize this ester for the way it improves texture and supports skin comfort.
- Skin conditioning – softens and smooths the skin surface helping it feel supple while reducing the appearance of rough patches
- Emollient – forms a light protective film that slows water loss boosting immediate and long-term hydration without heaviness
Who Can Use Isotridecyl Isononanoate
This ester is considered friendly for most skin types. Oily and combination skin appreciate its light texture that sinks in quickly without a slick residue while dry and mature skin benefit from the extra softness it lends. Sensitive skin generally tolerates it because it is non-fragrant and has a low risk of irritation. The only group who may want to be cautious are those extremely prone to breakouts from any oil-like substance since individual responses can differ.
Isotridecyl Isononanoate is synthesized from plant-derived or lab-made building blocks and involves no animal by-products, so it is suitable for vegan and vegetarian lifestyles.
There is no published data suggesting the ingredient poses a specific risk during pregnancy or breastfeeding when used topically in normal cosmetic concentrations. That said this is not medical advice and anyone who is pregnant or nursing should have a quick chat with their healthcare provider before adding new skincare just to be safe.
The ester does not increase sun sensitivity and can be worn during the day without raising the risk of burns. It also plays well with common actives like retinol, vitamin C and chemical sunscreens because it is chemically stable and non-reactive.
Potential Side Effects/Adverse Reactions
Responses to topical Isotridecyl Isononanoate vary from person to person. The following list covers possible side effects though most users experience none when the ingredient is formulated and used correctly.
- Minor irritation – a small percentage may notice temporary redness or a stinging sensation
- Contact dermatitis – very rarely an allergic reaction can develop leading to itching flaking or a rash
- Clogged pores – individuals highly prone to comedones might experience an uptick in blackheads or whiteheads if they use rich formulations containing high amounts of the ester
If any discomfort or unusual reaction occurs discontinue use and seek advice from a qualified healthcare professional.
Comedogenic Rating
Rating: 1/5
Isotridecyl Isononanoate has a branched structure that allows it to spread easily without forming a heavy occlusive layer. This lightweight profile lets skin breathe and makes the ester far less likely to trap dead cells or sebum compared with thicker straight chain oils. Real-world feedback and limited laboratory data both point to a very low pore-clogging tendency.
Most people who are prone to acne can use products containing this ingredient without seeing a spike in breakouts, especially when the overall formula is designed for oily or combination skin.
The final impact on pores depends on how much of the ester is used and what other ingredients surround it, so texture lightness in the finished product still matters.
Summary
Isotridecyl Isononanoate acts mainly as a skin conditioner and emollient. It forms a thin silky film that slows water loss, smooths rough spots and leaves skin feeling soft yet non-greasy. Its branched ester design mimics natural lipids which helps it integrate smoothly into a wide range of creams, lotions and makeup while boosting spreadability.
The ingredient is a behind-the-scenes workhorse rather than a headline star. It appears in many modern formulas because it improves feel and stability, but it rarely gets called out in marketing so casual shoppers may not notice how often it shows up.
Safety studies plus decades of use suggest a very low risk of irritation or sensitization for the average consumer. Still every skin is unique so it is wise to patch test any new product that features this or any other ingredient just to be sure it agrees with you.