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Antibiotics do have effect on the contraceptive effect of birth control pills but it mainly depends on the type of antibiotic used.But at least for the time period during the drug intake and one week after another from of protection should be used for sexual contact.
Some drugs as antitubercular and anti leprosy drugs cause major alteration in the efficacy.Combined pill and progesterone pill have much interaction with any other drug.
Continue taking the pills regularly at the same time daily.
If you notice any unusual symptom visit a Gynaecologist for evaluation.
Take care!