Hello, I ve been taking doxycycline for acne for about four months. My period which is normally regular, has been late since I started taking the medication. I have been getting the symptoms of having a period when I m supposed to actually have one, but then it always seems to come late. Could that medicine be affecting when my period comes? I am sexually active and usually safe, but not always. I understand the consequences of unsafe sex, however I would like to know about the effects of the medication as well. Thank you!