Zithromax (azithromycin) is a popular prescription macrolide antibiotic specially designed to treat a wide array of infections caused by the presence and multiplication of bacteria in your body. Zithromax is usually well tolerated with only a few side effects possible. The following ones can occur: vomiting, decreased sense of taste, skin rash, dizziness, insomnia, mild nausea, diarrhea, mild itching, headache, stomach pain, ringing in your ears, and constipation. Although more serious side effects are also possible, they are quite rare. The following ones may occur in a very small number of people using Zithromax: stomach pain, low fever, loss of appetite, sore throat, chest pain, clay-colored stools, nausea, yellowing of the skin or eyes, watery or bloody diarrhea, and dark urine. Never take more of Zithromax and seek emergency medical help if you happened to take too much of it and experience such symptoms as nausea, vomiting, diarrhea, and stomach discomfort. Make sure you throw away any medicine that is outdated, as otherwise it may be harmful for your health. Do not store the liquid medicine for longer than 10 days as it stops being efficient after this period once started.