If you use a condom as a backup method, you should be fine. There's no way to know exactly how much it reduces the effectiveness of birth control.

Actually, antibiotics and birth control pills have NO effect on each other. Antibiotics will NOT make your birth control pills loose their efficacy. There is NO clinical data proving that antibiotics effect the pill. The ONLY antibiotic that is KNOWN to effect the pill is Rifampin, which is used to treat tuberculosis.

The idea that antibiotics effect the pill is common myth. I spoke to one of the top accredited OB-GYN's in the midwest, who firmly told me that antibiotics do not effect the pill. Only Rifampin could have adverse effects.

Many people, however, choose to take the "better safe than sorry" approach. It is recommended by some to use back-up (such as a condom) during the course of antibiotics and at least 7 days after.

rockon0159, I was going by the contraindications listed with minocycline. Since every website I visited stated that minocycline could reduce the effectiveness of birth control pills, including drugs.com, cigna.com and the National Institute of Health website, I think anyone that ignores that warning is asking for trouble.
As for studies, one website states:
For most women, most birth control pills, and most antibiotics, there shouldn't be a problem. The pill should continue to work well during the week or two you're taking the medicine. However, medical studies have found that in some women, common antibiotics can reduce the amount of estradiol, or the hormone in birth control pills, in the bloodstream. If the level of estradiol gets too low, the drug won't work to prevent pregnancy.
Another says: "One of the most common causes of birth control pill failure is something many women often aren't even aware of: it's antibiotics. There have been various reports throughout the years that antibiotics can make the pill less effective. Now an overview report finds this can be a very real concern.

"The theory is that antibiotics may cause enzymes in the liver to speed up their metabolic activity so they break down birth control pills faster while also blocking absorption. Levels of the birth control hormone drop and the women become vulnerable to getting pregnant.

"While the studies find only a small decrease in effectiveness, it is enough for a word of caution. If you take birth control pills - especially the low dose kind - and also take antibiotics, protect yourself with additional contraception or you may be in for a surprise nine months later."
The Mayo Clinic says this: The effects of antibiotics on birth control pills may be overstated — except in the case of one antibiotic, rifampin. Studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation. However, rifampin isn't used widely. Chances are you wouldn't be taking it unless you had tuberculosis or had tested positive for the disease.

Hypothetically speaking, other antibiotics, particularly penicillin and tetracycline derivatives, could impair the effectiveness of birth control pills in a small percentage of women. Researchers can't rule out this possibility, but no large studies have proved such an effect.

If you're taking a newer, extremely low-dose oral contraceptive, you could be more susceptible to this potential antibiotic effect. If you're concerned, consider using a barrier method of contraception for the duration of your antibiotic prescription.

* I have links to all the quoted articles but I don't want anyone to turn me in for advertising. If you would like the links I would be happy to send them to you in a private message. *

I have also read these articles (I've researched a lot about this). It is my understanding that in a very small percentage of women, antibiotics may reduce the effectiveness of the pill. In scientific trials, it is very possible that statistics representing these women were not available since WHY exactly this happens is unknown. Since no root cause can be determined, women who may be effected cannot be pinpointed.
Of course, clinical studies are very different from real world experiences. It is very possible than in a good number of women, taking antibiotics with the birth control pill COULD make it not effective. These women, however, represent a small percentage of the whole.

I was quite contradicted surrounding this subject for a long time, until I spoke to a few very acclaimed, trusted doctors. These doctors told me that in reality, these antibiotics will not have an effect on my pills whatsoever. I do not believe it would be in these doctor's best interests to put their female patients at risk, and so I will continue to promote the idea that it is very unlikely antibiotics will effect birth control pills.
Since there is always that small chance, however, I will also recommend to those about to undergo a course of antibiotics that they consider back-up for the course of their antibiotics and at least 7 days after. But, it is reassuring to those who did not realize the contradiction until AFTER they were on antibiotics and the pill to hear that the actual chance that they are one of the rare women who may be adversely effected is slim.
Hope that cleared things up! Like I said, it's always better safe than sorry. I would always use back-up with antibiotics just because it's so easy to just put on a condom and not have to worry about it.

I am also taking minocycline with birth control and I had sex about a week ago and it was a very close call. I would definitely advise using a secondary form of protection or getting a higher dose birth control pill before having sex because you can never predict how the combination of minocycline and the pill will affect your body.
I wasn't that worried because I had read the same things online about antibiotics not really interfering with birth control, but right after I had sex, I got my period early...I called the clinic and they told me that that meant that the antibiotics had reduced the effectiveness of the pill to the point that I was reverting to my normal menstrual cycle and that it was basically offering me NO protection at ALL.
Thankfully, I had used a condom as well and was in the clear (as I was having my period), but it's scary to think that I was relying on the condom alone, which has like a 20% failure rate, thinking that I was almost 100% protected...