Bht

BHT (butylated hydroxytoluene) is an antioxidant used in cosmetics at low concentrations (typically ≤0.1%) to prevent rancidity. Clinical and patch-test data suggest it is generally well tolerated but can cause irritant or allergic contact dermatitis in a minority of users, especially those with compromised barriers (e.g., eczema). Given its documented sensitization potential despite low use levels, I rate it as mild rather than gentle for high-sensitivity populations. Safety Notes: In commercial cosmetics, BHT is used as an antioxidant to protect oils/fragrances and is often present at trace levels (~0.0001–0.01%) in mass-market leave-on creams, sunscreens, makeup, and fragranced products where it functions as a stabilizer. Many standard formulations sit around 0.01–0.1%, while the highest OTC consumer-available levels observed are in lipid-rich, oxidation-prone systems (e.g., anhydrous balms/sticks, certain hair oils/serums, and some long-wear color cosmetics) where brands may push toward ~0.2–0.5% for robustness. This range reflects real-world market use; BHT is typically similar in leave-on and rinse-off products, with the driver being oil load/oxidation risk rather than application type.