Hello,
For your first question regarding the effectiveness of the contraceptive when taken with Doxycycline (Doxyhexal).
Doxycycline will decrease the level or effect of
ethinylestradiol, so if you are using
oral contraceptive pills for birth control purpose.
Then there is a low risk of contraceptive failure when you are having sexual intercourse while taking doxycycline with your hormone pills, but it should not cause any significant adverse effects regarding your
irregular periods.
You may just feel no significant changes or improvement on your irregular period symptoms while you are taking such two treatment together.
For your second question, I cannot explain how your testing result confirmed to be positive for
chlamydia infection when both you and your partner are in a monogamous relationship.
Chlamydia trachomatis infection is a bacteria that infects cervix,
urethra, and
rectum, as well as nongenital sites such as the lungs and eyes.
If your doctor had a vaginal swab to make a diagnosis for chlamydia infection and it was confirmed to be positive, then the source of the chlamydia infection is
sexually transmitted disease.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Dr Katie Lee, General & Family Physician