Loestrin 24 Side Effects & Cycle Changes: A Patient's Experience

Question
Hello, I started taking Loestrin 24 in the beginning of September because I was getting married in November. My cycles really never regulated with my "placebo" pills and my MD said it would take time for my body to regulate. Anyways, I had a late period the week of Halloween approx 10/25-10/29/10. My next period came early in November approx 11/15-11/19/10. Approx 12/2 I was put on oral Septra for a UTI and Omnicef for strep throat. I continued taking my pills and my husband "pulled out" when we had sex. I have not had a period the whole month of december. I have taken 2 pregnancy tests at home the first test approx 12/24 and the second 12/28 both were negative. On 12/25 I started taking my placebo pills and restarted a new pack on 12/29 no period came. Should I worry that my period did not come? Could the antibiotics have decreased the effectiveness of the pill and could I be pregnant? or am I being paranoid?

Answer
It's not unusual with some pills like Loestrin that periods don't come.  As long as your pregnancy test is negative, I would continue taking the pill.  Antibiotics don't really decrease the effectiveness of the pill as is popularly believed.  If you wish to have periods, you could ask your doctor to switch you to a different pill.  I don't think you're pregnant.