effectiviness of pill while on antibiotics ?

Question

I have received contradictory information regarding the effects of antibiotics on birth control pills. What is correct and why does an antibiotic have that effect on the pill ?

Answer 1

Birth control pills contain estrogens. Some antibiotics, e.g., rifampin, griseofulvin, cause the enzymes in the liver to increase the break-down of estrogens and thereby can decrease the levels of estrogens in the body and the effectiveness of the pills. This can result in unwanted pregnancy. Therefore, individuals taking birth control pills should use a second method of birth control when taking these antibiotics or other drugs that can increase the break-down of estrogens.

The other way that antibiotics could interfere with the effectiveness of birth control pills is by reducing the re-circulation of estrogens within the body. Estrogens, e.g., ethinyl estradiol, in birth control pills are broken-down by conversion in the liver to other chemicals which are then secreted into the intestines in the bile that is produced by the liver. Bacteria in the intestine are able to convert these chemicals back into the active estrogen which is then reabsorbed into the body.. This re-circulation is called entero-hepatic cycling. Antibiotics kill the bacteria that convert the inactive chemicals to the active estrogen, and, therefore, interfere with the effectiveness of birth control pills. Unwanted pregnancies could occur. Drug manufacturers caution that antibiotics could decrease the effectiveness of birth control pills. Since it is better to be safe than sorry, individuals taking birth control pills are advised to use a second reliable method of birth control when taking antibiotics.

Rifampin (brand name Rifadin), penicillin (Veetids), amoxicillin (Amoxil), ampicillin (Omnipen), cotrimoxazole (Septra or Bactrim), tetracycline (Sumycin), minocycline (Minocin), metronidazole (Flagyl), and nitrofurantoin (Macrobid or Macrodantin).

Hope it helps.

Answer 2

Antibiotics reduce the effectiveness of the pill. While on antibiotics you should use a second form of birth control to avoid pregnancy. The Antibiotics effect the way the hormones are absorbed by your system.

Answer 3

Certain antibiotics can interact with birth control pills, making the birth control pills less effective and pregnancy more likely. Spotting - or ‘mid-cycle’ bleeding - may be the first sign that an antibiotic is interfering with the effectiveness of your birth control pills.
Antibiotics that have been shown to interact with birth control pills include rifampin (brand name Rifadin), penicillin (Veetids), amoxicillin (Amoxil), ampicillin (Omnipen), cotrimoxazole (Septra or Bactrim), tetracycline (Sumycin), minocycline (Minocin), metronidazole (Flagyl), and nitrofurantoin (Macrobid or Macrodantin).

To help women avoid pregnancy while taking an antibiotic - and for at least one week afterward - doctors generally recommend they use a condom or spermicide as a back-up method of birth control. If you are taking both antibiotics and birth control pills, be sure to check with your doctor about how long you should continue to use a back-up method. Also, discuss any other questions you may have about this information.

Answer 4

Most (not all) antibiotics affect the pill enough that you should use backup the entire time you are on the antibiotic and for 7 days following the antibiotic (to establish your protection again). They use this as a general guideline for all antibiotics because its easier than pointing out the few exceptions.

Answer 5

Some drugs reduce the effect of the Pill and can cause breakthrough bleeding, or increased chance of pregnancy. These include drugs such as rifampicin, barbiturates, phenytoin and carbamazepine. In addition cautions are given about broad spectrum antibiotics, such as ampicillin and doxycycline, which may cause problems "by impairing the bacterial flora responsible for recycling ethinylestradiol from the large bowel".
http://en.wikipedia.org/wiki/Birth_control_pill#Drug_interactions

I've been on birth control for 6 years and I've taken several antibiotics for bacterial infections and I've never experienced any side effects, or lose of effectiveness. But, certain antibiotics can, and do affect birth control.

Answer 6

Some say the pill will work fine and others say it won't. I wouldn't take a chance. Use a backup plan! Also, how can anyone tell you how your body will respond to the pill and the antibiotic? We're all different.

Answer 7

I dont think it does have any interactions or effect. Antibiotics kills bacteria, while pills act on a different site or mechanism of action. Pills are hormones that alters the balance of progesteron and estrogen so that pregnancy will be inhibited or prevented.
The danger that it can pose is you can be pregnant even when using pills and when you take antibiotic that can ruin or deform the baby. Otherwise you can quite take both without worrying anything except to be sure you are not pregnant!

Answer 8

It depends on which antibiotic, like Jennifer said. Always ask your doctor.

And here's another lesser-known tidbit: general anesthesia can affect the pill too. After being under it for a minor surgery, even though I had been on the pill for years, it caused me to ovulate and then came baby number 2. I never heard it before it happened to me, but the anesthesiologist verified it for me when I asked later.

Answer 9

yes some antibiotics does effect when taking the pill, especially penciling, I know this because I got pregnant while taking the pill because I was on penciling, how ever your doctor should tell you, and the pharmacies, but when taking other medications you should mention to the pharmacies that you are on the pill so they can look and see if you can take that medication while on the pill

Answer 10

boy can I answer that one,,,,,, just found out I am 12 weeks pregnant , was using the pill, but was also takin some antibiotics,,,,, if you dont want to have a little one,,, be sure you use a little something extra along with the pill,,,,,, doc just told me that!