Antiperspirants are composed of aluminum salts, sometimes combined with zirconium salts. Aluminum salts have the ability to precipitate, and their astringent action enables them to shrink the diameter of sweat ducts, thus reducing the flow of sweat. Bacterial flora is also locally inhibited. Aluminum chlorohydrate is the most common antiperspirant today, but many other aluminum salts are still in use. Despite the 0.6% limit on pure aluminum in antiperspirants, these are still implicated in contact eczema, irritation, breast cancer, Alzheimer's disease, Parkinson's and other degenerative diseases, encouraging people to turn to natural antiperspirants, namely alum stone. While the aluminum content of natural alum stone appears to be lower than that of conventional antiperspirants, its long-term safety has not yet been proven. Known and used since Antiquity, alum stone does contain aluminum. In fact, it's a double sulfate of aluminum and potassium (Potassium Alum) [1]. It can be found in several forms: either natural, in which case it comes as n the form of a recrystallized mineral extracted from quarries; or synthetic, in which case it's no longer composed of Potassium Alum, but of ammonium aluminum sulfate (Ammonium alum). Naturally astringent, it clogs pores and sweat glands, mechanically limiting perspiration and the odors associated with it. Whether natural or synthetic, alum stone contains aluminum salts recognized as toxic by scientists. Although alum stone is well tolerated most of the time, certain sensitive skins can be irritated by it, as was the case with our two patients who used this stone in association with talcum powder, which potentiates the occlusive effect on pores and sweat glands and increases the risk of complications. talc is actually magnesium silicate powder, a natural mineral in the same family as clay. Talc's absorbent properties enable it to eliminate excess sebum from skin and hair. It also forms a protective film on the skin, protecting it from dehydration and external aggression [2].