The main active ingredient in birth control pills is usually estrogen, combined with either a progestin or progestogen.

The most commonly prescribed birth control pills in the US are:

1. Low-dose combined pill - contains 20-35 mcg of estrogen with 100-150 mcg of progestin.

2. Extended cycle combined pill - contains 20-35 mcg of estrogen with 100-150 mcg of progestin, but is taken for a full 24 or 28 days in a row, instead of the usual 21.

3. Progestin-only pill (POPs) - contains 30-150 mcg of a progestin hormone (levonorgestrel, norgestimate, desogestrel, or gestodene). This option is for women who are breastfeeding, have clotting disorders, or are taking a blood-thinner medication.

Some antibiotics have the potential to interact with birth control pills or progestin-only pills. These medications can affect the effectiveness of birth control and potentially increase the risk of an unintended pregnancy.

The following antibiotics may decrease the effectiveness of birth control pills or progestin-only pills:

1. Rifampin - This antibiotic is often prescribed for tuberculosis (TB) treatment. It can cause a rapid breakdown of the hormones in birth control pills, leading to an increased risk of unintended pregnancy. If you are taking birth control pills and need to start rifampin, it is recommended to use an alternative method of contraception during your treatment.

2. Griseofulvin - This antibiotic is often used to treat fungal infections. Like rifampin, it can cause a rapid breakdown of birth control hormones, leading to an increased risk of unintended pregnancy. If you are taking birth control pills and need to start griseofulvin, it is recommended to use an alternative method of contraception during your treatment.

3. Atazanavir - This antiretroviral drug is commonly used to treat HIV. Like rifampin and griseofulvin, it can cause a rapid breakdown of birth control hormones, leading to an increased risk of unintended pregnancy. If you are taking birth control pills and need to start atazanavir, it is recommended to use an alternative method of contraception during your treatment.

4. Topiramate - This anticonvulsant medication is often prescribed to treat seizures. It can lower the effectiveness of birth control pills by increasing the rate of elimination of the hormones from the body. If you are taking birth control pills and need to start topiramate, it is recommended to use an alternative method of contraception during your treatment.

In summary, certain antibiotics (rifampin, griseofulvin, atazanavir, and topiramate) can interact with birth control pills or progestin-only pills, leading to a decreased effectiveness of these medications. To avoid unintended pregnancy, it is important to discuss all medications you are taking with your healthcare provider and explore alternative methods of contraception during antibiotic treatment.