You should always wait until you have finished all of your medication for chlamydia (or any other curable STD) and have had a follow-up examination before having sex with someone. Your sexual partner(s) should also complete treatment as well before you have sex again. Even if either of you had symptoms that went away, this does not necessarily mean that the infection is cured. Finishing all of your medicine and following up with your health care provider is the only way to be sure the infection is gone and will not be passed to another person.