What is amoxicillin? Amoxicillin is a penicillin antibiotic that fights bacteria. Amoxicillin is used to treat many different types of infection caused by bacteria, such as tonsillitis, bronchitis, pneumonia, and infections of the ear, nose, throat, skin, or urinary tract. Amoxicillin is also sometimes used together with another antibiotic called clarithromycin (Biaxin) to treat stomach […]