Does Guarana Interfere with Birth Control Pills?

I purchased a daily multi vitamin that has guarana and wonder if it would interfere with the effectiveness of my birth control pills (Ortho Tricyclene Lo)?

I don't know of any reason why guarana would interfere with your birth control pill. The main action of guarana is stimulation. Guarana does not significantly affect hormones or liver functionality in processing hormones. The only herb that I know of that may affect the effectiveness of birth control pills is St. John's wort, which uses the same liver enzyme to metabolize it.