I took the 3 day pack 500mg of azithromycin for chlamydia the last pill was on saturday when is it safe to have sex again.

Wrong dose: The proper treatment of chlamydia with azithromycin is a single dose of 1 gram (four 250 mg or two 500 mg tabliets). While it is likely that taking it over 3-4 days would work, it has never been studied and the effectiveness isn't known for sure. Discuss possible re-treatment with your doctor, or retesting in 3-4 weeks. And of course no sex with your former partner(s) until they have been treated.