BHT is a hindered phenolic antioxidant (2,6-di-tert-butyl-4-methylphenol) used at very low levels to intercept lipid peroxyl radicals and terminate autoxidation chains in oils, waxes, and oil-soluble actives. In skin-care emulsions, anhydrous balms, and color cosmetics, BHT slows rancidification of unsaturated triglycerides and emollients, helping preserve odor, color, and viscosity while limiting degradation of sensitive actives (e.g., retinoids) and UV filters. Compared with natural tocopherols, BHT is thermally robust and remains effective through hot-process manufacturing and extended shelf life, making it a reliable option when distribution involves heat, air exposure, or long dwell times.

In hair-care, trace BHT protects the perfume and lipid fraction in shampoos, conditioners, styling creams, and aerosols from oxidative breakdown that can lead to off-notes, discoloration, and loss of performance. Its role is formulation-centric rather than a direct “active” on skin or hair: BHT resides in the oil phase, acting as a radical scavenger to keep the product’s sensorial profile and efficacy consistent from first to last use. Regulatory bodies in major markets allow BHT in cosmetics; the EU Scientific Committee on Consumer Safety (SCCS) has assessed it as safe in leave-on and rinse-off products within specified limits, and multinational manufacturers routinely use it at very small percentages.