Please help soon-should I take Plan B?

[miss_thing]

I have been taking birh control pills for about 10 years, the current one being Yasmin, for about 7 months. I got my period July 17th like normal. Since I started the new pack on July 22, I haven't missed any pills or taken any late. Here's my dilemma: I was on antibiotics (ampicillin) from Monday, July 30 until Saturday August 4. (I still took my pill as normal.) I had unprotected sex Sunday night, Aug. 5. Could I be pregnant? I called my gyn and she said it could be possible (it may be my "fertile" time) and to take Plan B (she already called in a prescription). I only have 5 more pills in this pack, I'm due to get my period on Tuesday, Aug. 14. I just don't know what to do! What are the chances that I might be pregnant anyways? It seems like Plan B can mess your system up too, so I'm afraid to take it. Please help.....anyone.

[Post-It]

Wow I'm kind of shocked your gyn told you it might be affected, then again she just may not know better.

Antibiotics, such as penicillins (ampicillin, amoxicillin), tetracyclines, or metronidazole (Flagyl), do not change the effectiveness of birth control pills.

The ones you should watch out for are:

* St. John's wort.
* Certain antibiotics such as rifampin (Rifadin) and griseofulvin (Fulvicin).
* Anticonvulsants, such as carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), and primidone (Mysoline).
* Narcolepsy medications, such as modafinil (Provigil).
* Antiretroviral protease inhibitors used to treat HIV, such as Ritonavir.

[krzykat]

If you do end up taking Plan B it shouldn't have too drastic an effect on your menstrual cycle. I have taken it once in the past and got my period exactly one week after taking it.

This could of course be different for others.