Michael said: "The single large dose of Zithromax that is prescribed to treat sexually transmitted infection of the cervix or urinary tract infections caused by chlamydia. Azithromycin is in a class of medications called macrolide antibiotics which works by stopping the growth of bacteria. It is found to be present in the body for a significant period of time after the required doses. The most widely used antibiotics available for sale at our online pharmacy. The single large dose of Zithromax that is prescribed to treat sexually transmitted infection of the cervix or urinary tract is more likely to cause stomach and bowel side effects. Azithromycin is in a class of medications called macrolide antibiotics which works by stopping the growth of bacteria. This medication may cause stomach upset, loose stools, loss of appetite, nausea, and pain in the abdomen."