Our bodies are constantly producing sweat, but there are certain times when they produce a lot more. Additional sweat is produced to cool down our bodies when we are exposed to heat, physical exertion, stress or nervousness. When the sweat gland is stimulated, the cells secrete a fluid that travels from the coiled portion of the gland up through the straight duct and out onto the surface of our skin . Solid antiperspirants are made with several ingredients, including wax, a liquid emollient and an active-ingredient compound. It's the active ingredient that gives antiperspirants their sweat-blocking power.
All antiperspirants have an aluminum-based compound as their main ingredient.
If you look at the back of an antiperspirant container, the aluminum-based compound is always the first ingredient listed. The aluminum ions are taken into the cells that line the eccrine-gland ducts at the opening of the epidermis , the top layer of the skin, says dermatologist Dr. Eric Hanson of the University of North Carolina's Department of Dermatology. When the aluminum ions are drawn into the cells, water passes in with them. As more water flows in, the cells begin to swell, squeezing the ducts closed so that sweat can't get out. When this happens, the water inside the cell begins to pass back out of the cell through osmosis, and the cell's swelling goes down.