Magnesium sulfate (Epsom salt) is a naturally derived mineral salt widely used in cosmetics for its texturizing, purifying, and relaxing properties. In formulations, it mainly acts as a bulking agent and viscosity modifier, improving texture, consistency, and spreadability. It also plays a key role in water-in-oil (W/O) emulsions, where it helps strengthen the structure and reduce phase separation. Within a formulation, magnesium sulfate also provides astringent and sebum-regulating properties, helping to absorb excess oil, refine the appearance of pores, and leave the skin looking clearer. It helps purify the scalp and adds lightness to the hair. It is also famous for its relaxing properties. When dissolved in bath water, it can help soothe tired muscles and relieve minor aches and tension. Commonly used in bath salts, scrubs, and masks, it is ideal for creating exfoliating or remineralizing treatments. Studies show that it is non-irritating and non-sensitizing at typical cosmetic use levels (up to around 25% in rinse-off products and 11% in leave-on products).