i've read alot on these boards and every other medical info i could get my hands on. but i still dont understand how exactly antibiotics decrease the effectiveness of BCPs. i understand that antibiotics and upset your stomach which would cause you to vomit and diarehea(sp) is another bi-product of taking antibiotics. and that aspect i can see how the effect BCPs since that interfers with absorbtion. but what i was wondering is if thats the only reason why they effect BCps or if its a direct chemical interference in which its the antibiotics(because of whats in them) that decreases the effectiveness of BCPs?

I would love to know the answer to that one too. I was on Amoxcicillin and BC in 1990. And today I have a wonderful 12 year old daughter that was concieved on the Pill. I wouldnt change a thing mind you but I would love to know how it knocks out the pill. Anyone know?

------------------
Cheers...Autumn
Female...42
TMJD...12 years
Anxiety/Panic Attacks (cured I hope)
Total Abdominal Hysterectomy due to endometrial bleeding after miscarriage (2002)
Hernia Repair(1998)
Apendectomy (infected) 1988
21 year old daughter born with Mullerian Aplasia
18 year old daughter bulimia survivor.
If I can help ANYONE with anything from a papercut to a life threatening illness, I will do my best just to be a friend. " A friend is someone who knows all your faults and loves you anyway".

thanks for your reply. does anyone else have any information it would be a big help

From rxlist:

Interference with Enterohepatic Circulation

Ethinyl estradiol conjugates are excreted in the bile and may be broken down by gut bacteria in the colon to liberate the active hormone which can then be reabsorbed. However, there are clinical reports that support the view that enterohepatic circulation of ethinyl estradiol decreases in women taking antibiotics such as ampicillin, tetracycline, etc.

Basically, it circulates through your liver as a prodrug, and is broken down into bits called conjugates, excreted into your digestive tract in the bile, and converted into hormones. Certain antibiotics can decrease the prodrug circulation through your liver, which would mean less is broken down, and therefore less is available to be absorbed. Especially considering most bcpills available now are low-dose bcpills, a small drop in blood serum level can cause a reduction in effects.

thanks for replying wrin that helps alot. and since you know alot about this do you know if ortho tri cyclen is a a low-dos pill. so just to clarify even if you dont vomit or have diarehea the antibiotics with still effect them?

Yes, even if you don't vomit or have diarrhea, the antibiotics will still affect them, because the antibiotics don't just affect your stomach and your bowel -- they affect your liver's circulation too, and that's where the big problem comes from, since the liver is such a big chunk of how the drug is used.

Yes, ortho tri cyclen is technically a low-dose oral contraceptive -- the doses used these days are MUCH MUCH ower than the ones used in the 70s. That's why they're safer and have fewer side-effects.

You can still get special high-dose oral contraceptives (usually containing more than 50 (mg?) of ethinyl estradiol,) but these are only used in special cases, where the regular pill is not enough.

wow thanks so much wrin, i think i'll just direct my questions to you from now on. once again thanks alot. hey autumn i hope this helped you too.

So how come when I take my bc and my antibiotics, it still keeps my cycle regular? I've always wondered why it kills the birth control part but my periods still come on exactly the same cycle.

------------------
"Never give up, never surrender!"