Amoxicillin is used to treat certain infections caused by bacteria, such as pneumonia; bronchitis; gonorrhea; and infections of the ears, nose, throat, urinary tract, and skin. It is also used in combination with other medications to eliminate H. pylori, a bacteria that causes ulcers. Amoxicillin is in a class of medications called penicillin-like antibiotics. It works by stopping the growth of bacteria. Antibiotics will not work for colds, flu, and other viral infections.