Microcrystalline Wax

Microcrystalline wax is an inert, occlusive structuring agent (typically ~1–20% in balms, sticks, and ointments) that is generally well-tolerated and not a common irritant in patch testing. However, in severely compromised or eczema-prone skin, heavy occlusion and rubbing during application can contribute to discomfort or follicular occlusion in a minority, so it is best scored as very gentle rather than completely inert for patient safety. Safety Notes: In commercial skincare, microcrystalline wax is often used at very low levels (~0.1–1%) as a viscosity builder/structurant in creams, body lotions, and cleansing balms, where it subtly thickens without materially changing skin feel. The highest consumer-available levels are found in anhydrous stick and balm formats (lip balms, barrier/protectant balms, anti-chafe sticks, solid perfume/ointment-like products), where microcrystalline wax can function as a primary structuring wax and commonly reaches ~15–35% depending on hardness target and the blend with petrolatum/oils. It is predominantly a leave-on structurant; rinse-off products rarely require high levels because excessive wax can impair rinseability.