Hello Thanks for writing to us with your health concern. CHlamydia is a sexually transmitted infectious organism. It is acquired by sexual contact. There is no way that an EC can cause you to have Chlamydia. You probably acquired it from unprotected sex from your current partner or earlier. It is good that you took the antibiotic course. Most chlamydial infections are often silent ( asymptomatic ) however they might lead to complications such as sterility, bladder infections, pelvic pain and adhesions in the long run, without any obvious symptoms. This infection should always be treated properly and thoroughly eradicated because it might cause such complications. You should have a repeat examination after 6 weeks to ensure that the infection is obliterated. A vaginal swab will confirm that. Your partner also should be checked for Chlamydial infections and other STDs. All said and done, it CANNOT be the result of intake of EC or any other medication. It just showed up because you had it, plain and simple. Have protected sex till you heal up completely and your partner is clear. All the best Take care.