Expert answer:
If you took a medicine that can cut or decrease the contraceptive effect, as an antibiotic or anticonvulsant, the contraceptive may take up to a week to come back to take effect.
Therefore, while you are taking this medicine you should use another contraceptive method not hormonal, as a condom, so as not to risk becoming pregnant.
However, it is important to remember that there are few drugs that cut the effect of contraceptive, especially if it is the pill of continuous use. For further information, contact your gynecologist, family doctor or general practitioner.
