This finding was in good accordance with the literature, where the hydroquinone is routinely shown to auto-oxidate under these conditions 30,31
It binds and unbinds in a constant exchange, so some free copper ions escape and irritate local nerve endings while activating mast cells (immune cells that release histamine and trigger inflammation)
A reduction in experimental lesions may indicate cytoprotection-associated activity in a controlled model, but it does not necessarily explain whether the primary driver is endothelial preservation, anti-inflammatory signaling, epithelial restitution, altered motility, or a combination of these processes
Using them in separate routines (AM/PM) or on alternate days is safer for sensitive skin
Annals of Allergy, Asthma & Immunology, 131(2), 250-255
Quantity: 200 g