According to WebMD, a bacteria-fighting antibiotic known as azithromycin is commonly referred to as the Z-Pak by patients and health care professionals. This prescription drug is typically taken once per day and cannot effectively treat viruses, but it does effectively treat bacterial infections, says WebMD.
MedlinePlus states that sexually transmitted diseases, upper respiratory infections and sinus issues are a few of the bacterial conditions that doctors treat with the Z-Pak. It can be taken with meals or on an empty stomach, and it is available in liquid or tablet form. Users should contact a doctor if serious side effects occur, such as wheezing, muscle weakness or hives, according to MedlinePlus.