Most types of medicine, if taken regularily for acne, etc should not interfer w/ birth control. The thought is that antibiotics MIGHT interfer but there's no proof. Also, Spiro isn't an antibiotic and generally prescribed w/ a birth control pill so it was never thought to interact in bad ways.
I have been on Yasmin for about 5 or 6 months. A month and a half ago, my dermatologist prescribed me 50 mg of spironolactone daily. I asked him if being on Yasmin was a problem since some people on this board have said that Yasmin has spiro in it and he said not at all. He said that Yasmin does not have spironolactone in it and thought the combination would work well since both have anti-androgenic properties....and it has!
From what I understand, Yasmin does not contain Spiro, but has a molecular structure similar to that of Spiro... that is it blocks the androgen receptors. Yasmin is the equivalent of taking 25/mg of Spiro a day, or so I have been told. You can take Spiro & Yasmin together... its actually a popular combination and is highly prescribed. The drugs will not interact with one another.