Broad-spectrum antibiotics as Zithromax can sometimes cause inflammation of the bowel. The effectiveness may be decreased and the bacteria may become resistant to antibiotics. Your doctor may advise you to stop breastfeeding until your treatment is finished. Common side effects of Azithromycin are normally well tolerated. Zithromax should be taken on an empty stomach two hours after a meal since food reduces its absorption. This drug is that it is found to be present in the body for a significant period of time after the required doses.