For how long is azithromycin effective in your body?

5 or more days: Depending on how long you have taken the medication, azythromycin is generally active in the body for 5 or more days after your last dose. It is not uncommon for some conditions to not completely or be only slightly improved when you take the last dose since it does continue to act for several more days. Call your doctor if you are not better within that 5 day period.

Two answers: Azithromycin in a single 500 mg dose has a half-life of 11–14 h. When multiple doses are taken it may increase to 68 h. For a 5 day course it should be present 10 days. Biliary excretion, predominantly unchanged, is a major route of elimination. Over a week, approximately 6% of the administered dose appears unchanged in urine. Efficacy is another subject.