Is it ok if I took Mercilon and Doxycycline one time only? (Cos i didnot know)

Patient: Today is my first time on pill, which is on my first day of my period of this month. I already took one for today. However, I’m currently using Doxycycline-100 and did not know that it can reduce effect of birth control. I only take Doxycycline for one day with Mercilon and will stop taking Doxycycline from now onwards. But does one time for today taking Doxycycline will affect Mercilon immediately? Please give me answer as this is the first time im on bill. Now I feel so scared as I just realized this after taking Doxycycline 5 mins ago. Can I still continue to take Mercilon normally from now onwards if I stop taking Doxycycline?Thank you!

Doctor: Thank you for your question. You can continue to take your birth control pill as scheduled. This one dose of doxycycline may reduce the efficacy of your birth control pill for the next 48 hours so we recommend that you use barrier protection during this time if you are engaging in sexual intercourse. After this time, you may continue to take your birth control pill as scheduled without complication.Thank you for choosing