Magnesium Chloride

Magnesium chloride is primarily a humectant/mineral salt used in leave-on products (often ~0.5–5%) and much higher in “magnesium oil” sprays, where its high ionic strength can sting and feel burning on compromised skin. Clinically, concentrated salt solutions are well-known to cause transient irritation on eczema, fissures, and post-shave skin even without true allergy, so I score it as mild rather than gentle for patient safety. Safety Notes: In mainstream skincare, magnesium chloride is most often a minor electrolyte/mineral component or part of Dead Sea/mineral blends in toners, mists, lotions, and cleansers, where finished-product levels commonly start around ~0.05–1%. At the high end, consumer-available topical “magnesium oil” sprays/gels and mineral brines (leave-on body products) are formulated from concentrated MgCl2 solutions, with typical anhydrous-equivalent magnesium chloride levels roughly ~20–35% depending on hydration state and sensory limits. EU/FDA do not set a specific cosmetic maximum for magnesium chloride, so practical constraints are irritation potential, tackiness, and crystallization, with rinse-off products usually formulated lower than leave-on brines.