What Is Octadecenedioic Acid?
Octadecenedioic acid, also called 9-octadecenedioic acid, is an 18-carbon dicarboxylic acid with one unsaturated bond sitting near the middle of the chain. In practice it is obtained by oxidizing renewable plant oils rich in oleic acid, such as sunflower or rapeseed, or by using bio-fermentation that converts those same feedstocks with the help of environmentally friendly microbes. The result is a biodegradable ingredient that fits well with the push for greener cosmetic chemistry.
The beauty industry started looking at long-chain dicarboxylic acids in the late 1990s for their ability to improve product stability without relying on petroleum-derived raw materials. Octadecenedioic acid proved particularly attractive because its single double bond gives it enough flexibility to form stable, elegant emulsions while still being robust under a range of pH and temperature conditions. As manufacturing methods became more cost-effective during the 2000s it found its way into mainstream personal care formulations.
Today you can spot octadecenedioic acid in creams and lotions that need a silky, non-greasy feel; in hydrating serums and masks that suspend both water- and oil-based actives; in daily moisturizers that claim a light texture; in anti-aging or brightening treatments where consistent spreadability is key; and even in modern sunscreens where multiple UV filters must stay evenly dispersed.
Octadecenedioic Acid’s Cosmetic Benefits/Uses
Its primary role in skincare is as an emulsifying agent. In a formula that blends oil and water phases, octadecenedioic acid positions itself at the interface, keeping the two phases mixed so the product does not separate on the shelf or on your skin. A stable emulsion means a smoother texture, more even delivery of active ingredients, longer shelf life and an overall pleasant sensory experience every time you apply the product.
Who Can Use Octadecenedioic Acid
Most skin types tolerate octadecenedioic acid well, including dry, normal, combination, oily and sensitive skin, because it is primarily an emulsifier rather than an active exfoliating or highly acidic agent. If you are extremely sensitive or have a known allergy to fatty acids you may want to approach with caution, but such cases are rare.
The ingredient is sourced from plant oils or produced through bio-fermentation, so it is suitable for vegans and vegetarians. No animal-derived materials are involved in its standard supply chain.
Pregnant or breastfeeding individuals are not expected to face specific risks from topical use of octadecenedioic acid, as it has no known hormone-related activity and is used at very low concentrations. This is not medical advice and anyone who is pregnant or nursing should show all skincare products to a qualified physician to be certain they align with personal health needs.
Octadecenedioic acid does not increase photosensitivity, so you do not need added sun precautions beyond the usual SPF recommendation.
Potential Side Effects/Adverse Reactions
Responses to cosmetic ingredients vary from person to person. The following is a list of potential side effects that could occur with topical use of octadecenedioic acid, though most users will not experience them when a product is formulated correctly.
- Mild skin irritation such as redness or itching
- Transient stinging on very compromised or broken skin
- Contact dermatitis in individuals allergic to fatty acids
- Clogged pores or breakouts if the overall formula is too rich for your skin type
If you notice any unwanted reaction stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1/5. Octadecenedioic acid is a long-chain dicarboxylic acid that adds slip without the heavy, greasy residue linked to more pore-clogging fatty acids. Its dual acid groups improve water dispersibility, which helps it rinse away more readily than straight oils. Most formulas use it at low levels strictly to stabilize emulsions, so its contribution to pore blockage is minimal.
Because of this low rating, the ingredient is generally considered suitable for acne-prone or breakout-prone skin as long as the rest of the product is also lightweight.
If a formula combines octadecenedioic acid with rich butters or waxes the overall product could still feel heavy, so always look at the full ingredient list when judging pore-friendliness.
Summary
Octadecenedioic acid works as an emulsifier that keeps oil and water blended, improves texture, and extends shelf stability. It accomplishes this by anchoring its hydrophilic acid groups in the water phase while its hydrophobic carbon chain aligns with oils, creating a uniform mixture that feels silky rather than greasy.
The ingredient is moderately popular, found more in modern green formulations than in legacy products, largely because its plant-derived supply chain and biodegradability align with clean beauty trends.
Overall safety is high, with irritation or allergy being uncommon and concentration levels low. As with any new skincare product it is wise to perform a quick patch test to ensure personal compatibility.