Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
The cause of the interaction is not known. When these two medicines are taken together, your body may process the estrogen in birth control pills more quickly.
What might happen:
The effects of your birth control pills may decrease and cause pregnancy, breakthrough bleeding, or an irregular menstrual cycle.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. They may already be aware of this interaction and may be monitoring you for it. If your doctor prescribes these medicines together, it may be necessary to change the dose of your birth control pills. It may also be necessary to change to a different form of birth control. The effects may last for up to one month after you finish taking griseofulvin. Contact your doctor if you experience pregnancy, breakthrough bleeding, or an irregular menstrual cycle. Do not start, stop, or change the dosage of any medicine before checking with them first.
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