Octadecyl Di-T-Butyl-4-Hydroxyhydrocinnamate

Octadecyl di-t-butyl-4-hydroxyhydrocinnamate is a synthetic phenolic antioxidant commonly used in cosmetic and personal care formulations. It belongs to a class of stabilising agents designed to prevent the degradation of other active ingredients and preserve product integrity over time.This ingredient works by intercepting free radicals and reactive oxygen species that can degrade formulation components. Its long hydrocarbon chain (the octadecyl group) allows it to integrate into the lipid phases of creams and oils, making it particularly useful in emulsified and oil-based products.

This antioxidant functions by donating electrons to free radicals, neutralising them before they can cause oxidative damage to the product formula itself or, potentially, to the skin barrier. Its chemical structure—featuring hindered phenolic groups—makes it particularly effective at this electron transfer process.By remaining stable itself during this process, it can continue protecting formulations over extended periods, which is why it is typically found in moisturisers, serums, and oils rather than water-based products.

This ingredient is a background stabiliser rather than an active treatment. You do not need to dose your routine around it—simply use your product as directed. It is most commonly found in richer formulations like moisturisers, serums, and facial oils. Look for it in the ingredient list if you prefer products with synthetic antioxidant stabilisation over other preservation methods.

This ingredient is generally recognised as safe for topical use in cosmetics at permitted concentrations. It is not a skin irritant or allergen of particular concern, though those with severe sensitivities to synthetic ingredients may wish to patch test first.