Answer:
According to the WebMD site, it can make BCP less effective, ask your doctor if you need to use a back-up BC method while taking it.
Some brands of doxycycline should not be taken with milk, because milk interferes with the absorption of the antibiotic. You can ask your pharmacist for a brand that can be taken with milk if this is a concern.
This drug also makes you more susceptible to sunburn, be sure to use a sunscreen or avoid exposure.
Do not take iron supplements, multivitamins, calcium supplements, antacids, or laxatives within 2 hours before or after taking doxycycline.