• 99.7% effective with perfect use; less than one out of every 100 women will become pregnant each year
• 92% effective with typical use: 8 out of every 100 women will become pregnant each year

Additional Sources for Effectiveness Ratings and Use:

• 92% typical use/99.7% perfect use: Contraceptive Technology, 18th Revised Edition; Hatcher, Trussell, Stewart, Nelson, Cates, Guest, Kowal: Ardent Media, 2004.
• 92% typical use/ 97.7% effective perfect use: Feminist Women's Health Center
• 92% typical use/over 99% perfect use: Planned Parenthood

Some adolescent-specific studies on the pill have shown that it is less effective for adolescents in typical use than it is for adults. One study found that teens' ability to use the pill properly was as low as only 45% with the first three months of use, and 33% with one year of use. So, if you're going to use the pill, as with other methods, be sure you study up on what proper use means and make it a goal to stick to it as best you can.

The What, the Why, the Where, the When, and the How-to: The combination pill is called that because it uses two synthetic hormones -- estrogen and progestin -- to prevent pregnancy through an oral medication. Those hormones work in three ways: to prevent ovulation, to thicken cervical mucus to make sperm less able to get into the cervix, and by making the lining of the uterus thinner and thus, less hospitable for a fertilized egg to implant in. It works in all three of those ways to basically provide backup in case one of its mechanisms doesn't work at a given time.

The combination pill is one of the most popular methods of birth control, and it's also one of the most thoroughly researched and studied medications in history, so when your doctor makes sure you don't have any health conditions which would make the pill not-so-great for you, you can rest assured you are taking a method well-proven to be safe. However, certain women should not usually take the pill, such as smokers, women over 35, and women who are breastfeeding, diabetic or have a history of high blood pressure, cardiovascular disorders or high cholesterol. Be sure to discuss your health history and any current health issues with your healthcare provider so that they can be sure the pill is safe for you.

Some typical effects -- pro and con -- of the pill include lighter periods (though technically, women on hormonal methods have withdrawal bleeds, not actual periods), less cramping, decreased PMS symptoms, skin changes, an increase in the amount of time it takes to become pregnant after discontinuing, a more regular schedule of monthly bleeding, spotting between cycles, nausea, more frequent or more severe headaches, breast tenderness, mood changes or increased depression or anxiety, a decrease in sexual desire, vaginal dryness, water weight gain, and/or more frequent yeast infections. Some side effects had by a user of one pill may not be experienced with another. Rare but more serious side effects can include allergic reactions, blood clots, embolism or stroke, heart attack, gallbladder disease, thrombosis or eye problems.

In most countries, to get the pill, you'll need to visit your sexual healthcare provider (who may also be your regular doctor) to find out what brand is likely to be best for you and then obtain a prescription for the pill to fill at your pharmacy.

Some healthcare plans, national healthcare services and clinics will provide the pill for free to some or all women. For those who have to purchase pills themselves, they tend to cost between $15 and $50 each month.

To use the combination pill properly, you need to take one pill every day, ideally around the same time every day. Its also important to take your pills in order with most brands (monophasic types are an exception). If you don't take it at exactly the same time -- but still take it on the day you're supposed to -- that won't make your pills ineffective: it's just a safer bet to take it around the same time to keep you in the habit to reduce the risk of you spacing out a pill on any given day. As well, with a medication like the pill that's all about rewiring a very specific process in your body that changes daily, taking it as close to the same time each day as you can helps to be sure your hormonal levels are as perfectly regulated as possible. If you want to be as close as you can to a perfect-use effectiveness rate, you'll want to try and take your pills within the same three-hour window each day.

When you first start the pill, when it will be fully effective depends both on when you start it, as well as your own body chemistry. For most people who start the pill either on the first day of their period or the first Sunday after a period, any brand of combination pill will likely be effective after seven days of use, but here at Scarleteen, as many other credible sources suggest, we advise users to give their pills one full cycle before going without a backup to play it safe.

For detailed instructions on how to use your particular combination pill, you can refer to the insert that comes with your pill, or see our listing of links for specific pill instructions here.

Be aware that certain medications and substances may interfere with the effectiveness of the birth control pill. If you are using or have, in your current pill cycle, used, any of the following it's best to use a backup method of birth control (like a condom) until your next new cycle:

• Barbituates

• Tetracycline
• Cloribrate
• Neomycin
• Rifampin
• Chloramphenicol
• Penicillin
• Sulfonamide
• Ampicillin
• Nitrofuratonin
• Griseofulvin
• Benzodiazepines
• Metronidazole
• Fluconazole
• Anti-Migraine Medications

Know also that if you are currently bulemic, and cannot control your urge to vomit at any given time that the pill will not be a good choice, as it may be less effective if a woman is currently vomiting for any other reason or has diarrhea.

Some questions and answers about the pill:

• Quick Hits: Questions & Answers About the Pill
• How do birth control pills really work, even during the placebo period?
• Three questions about taking the birth control pill (and plenty of answers)
• Birth control pills: the placebos, period timing and condom backup
• Scarleteen Message Board users talk about their experiences using the pill for birth control

Or, click on the tag for birth control pills for a larger list.

When Good Birth Control Does Bad Things: The combination birth control pill may fail if it is not taken on time each day (if pills are taken late or missed, especially if more than two pills in a pack are missed or late), if pills are not taken in sequence, if a woman extends the placebo week of the pill too long (past seven days) any given time, if a woman stops taking her pills during the active pill phases, if it is used without a backup method when a user starts the pill for the first time, or if taken in conjunction with other drugs or substances which may interfere with it. While nearly all BCP failures are simply due to not taking the pill every day without fail, there are -- though they are rare -- some women for whom, even when taken perfectly, the pill does not work for.

Other methods which can be used as a backup method with the combination pill:

• Cervical Barriers (Diaphragms, Lea's Shield and Cervical Caps)

• Condoms
• Emergency Contraception (Plan B or the Morning-After-Pill)
• Spermicides
• the Sponge
• Withdrawal

Other methods you might like if you like the combination pill:

• the Contraceptive Implant (Implanon)
• the Contraceptive Patch
• Depo-Provera (The Shot)
• Emergency Contraception (Plan B or the Morning-After-Pill)
• Progesterone-Only Oral Contraceptives (Minipills)
• the Vaginal Ring (Nuvaring)

Why would the combination pill be a good option for me? If any of the following are true:

• You want a method which is highly effective when used properly

• You want some of the possible benefits the combination pill may offer, like the reduction of some kinds of acne, shorter, lighter periods, decreased PMS symptoms and help in preventing certain reproductive cancers
• You are looking for a method which you are completely in charge of yourself, where you don't have to rely on a partner to help with birth control
• You are looking for a method you can get easily internationally
• You are looking for an inexpensive method of birth control, or one you do not have to commit to pay for regularly
• You don't want a method you have to think about at the time you're going to have sex

For a very brief overview of all BC methods, have a look at Margaret Sanger's Disneyland: Choosing Contraceptives.

This is part of Scarleteen's Birth Control Bingo. Need to start over or anew? Click here.

Don't forget: Statistically, sexually active young adults are as, if not more, likely to acquire a sexually transmitted infection (STI) as you are to become pregnant. Although 15-24-year-olds represent only one-quarter of the sexually active population, they account for nearly half of all new STIs each year, and of the 18.9 million new cases of STIs each year, 9.1 million (48%) occur among 15-24-year-olds (AGI). Often people have some funny ideas about who is most likely to get an STI, but the fact of the matter is that younger people -- of any sexual orientation, any economic class, any kind of relationship -- have been the highest risk group for some time now.

Condoms are the only method of birth control which also provide protection against STIs. It's pretty typical for younger people to ditch condoms if they have another method of birth control, so just remember that STIs are still a risk if you're using another method. You can read all about safer sex here -- Safe, Sound & Sexy: A Safer Sex How-To -- but the rule of thumb most medical experts and prevention organizations suggest, which we also encourage at Scarleteen is six months of safer sex, six months of sexual monogamy, and then TWO full STI screenings for each partner -- once at the start of that six months, once at the end -- before ditching latex barriers.