Ampicillin is used to treat certain infections caused by bacteria such as meningitis (infection of the membranes surrounding the brain and spinal cord); and infections of the throat, sinuses, lungs, reproductive organs, urinary tract, and gastrointestinal tract. Ampicillin is in a class of drugs called penicillins. It works by killing bacteria.
Antibiotics like ampicillin will not work for colds, flu, or other viral infections. Taking antibiotics when they are not needed increases your risk of getting an infection later that will resist antibiotic treatment.