FAQ: Oral Contraceptives (the pill)

Due to the frequency of questions on this subject, I thought it would be helpful to create a FAQ. I'm also considering other FAQ-themed threads, but I'm starting with this. For what it's worth, I'm an RN, so I do know a thing or two about this. Forgive me for it's length, I'm just trying to be thorough. Also, I'm going to go ahead and assume that everyone knows that birth control pills do not protect against STIs or HIV....just as a disclaimer.



1) How does the pill work?

A woman's cycle can be thought of as 2 different cycles happening at the same time. One is called your ovarian cycle, the other is your uterine cycle.

The ovarian cycle refers to the development and release of the egg. A woman releases an average of one egg per month, typically at 14 days after the first day of her period. To further complicate things, the ovarian cycle has 2 different phases--the follicular phase, when the egg is developing, and the luteal phase, after the egg has already been released and the ovaries break down the rest of the "egg-developing" material. (Note: Ovarian cysts are caused when the ovaries either don't release the egg and it keeps growing, or they don't break down the material that's left after the egg is released.)

Think of a woman's cycle as having 4 weeks (on average) with Day 1 being the first day of your period, and Day 14 being the day you ovulate (release the egg). So, Week 1 is your period, Week 2 is the egg continuing to grow, Week 3 the egg is in the fallopian tube waiting to be fertilized, and Week 4 (the week before your period) your body is preparing for a possible pregnancy. Assuming no fertilized egg implants itself at this time, your hormones drop off, which causes the lining of your uterus (which has now become thick and engorged with blood to allow for a fertilize egg to implant itself) to shed itself and you start your period.

Birth control pills mimic Week 4 of your cycle, which brings me to the next FAQ....

Don't birth control pills mimic pregnancy?

No. Saying this is rather misleading, because during an actual pregnancy, you have additional hormones involved (HCG being one) and your levels of progesterone and estrogen skyrocket (during the later weeks in pregnancy) much higher than they would during your normal cycle. BC pills keep your body in the same state as the week before your period. During this time, you're not producing any more eggs, thus you're not fertile. Additionally, your "mucus plug" (lining of mucus outside your cervix) is thickened, preventing most sperm from coming in.

It doesn't mimic pregnancy, but you can think of it as having your body continuously prepare for a pregnancy that won't happen (assuming you take the pills correctly, we'll get to that in a minute.)

Is it safe to mess around with my hormones like that?

On average, yes. Women have been taking birth control since the 1960s, and if anything, they've gotten more safe, because the pill nowadays has much lower doses of hormones than it did when it first came out. The highest risk is developing blood clots, which is really only a big concern if you smoke, are over 35, are significantly overweight, or have other risk factors of getting a blood clot.

The thing to keep in mind is that all women are different, and you may find the pill does not agree with you. You may have more mood swings instead of less, weight gain, acne problems (although it helps acne for most women) breast tenderness, etc. Also, many women don't feel comfortable with the idea of it. If that's the case, then the pill probably isn't for you. While it works for a lot of women, nothing works for everyone.

Is it really safe to keep taking the pill and not have your period?

While not everyone is comfortable with the idea of it, if you do skip a period, the blood is simply re-absorbed by the body the same way that the ovaries re-absorb the remainder of the egg material, or your spinal fluid is cycled and re-absorbed by your spinal column. Also keep in mind that because of the nature of the pill (keeping you in week 4) the lining of your uterus isn't changing all that much, so it's not as though you're uterine lining is getting thicker and thicker and thicker until it bursts or something. The uterine lining changes even less if you're taking a monocyclic pill instead of a tri-cyclic, thus it's easier to skip a period if you take a monocyclic one.

What's the difference between mono-cyclic and tri-cyclic pills?

In tri-cyclic pills, you take 3 weeks of pills with a slight increase in hormones each week, until the 4th week when you take sugar pills (placebos that don't do anything). In mono-cyclic pills, you have a steady dose of hormones. Some women find that monocyclic pills cause fewer mood swings, since your hormones aren't fluctuating as much, and tricyclic pills are trickier to take, since forgetting a pill can throw things out of whack more easily.

What about the 'mini pill'?

The mini pill contains only progesterone, as opposed to the combination pills (the kind that most people on the pill take) which contain estrogen and progesterone. It's most often recommended for nursing mothers, because nursing mothers already have a higher level of estrogen and are thus less fertile anyway, so the mini-pill just acts as another layer of protection without interfering with breast feeding. The mini pill works by thickening the mucus plug and thinning the layer of the uterus, making fertilization/implantation less likely. If you take the mini pill by itself and are not nursing or using any other form of birth control, it is not recommended, since it's not as effective.

Will taking the BC pill cause a false positive on a pregnancy test?

No. Pregnancy tests only test for human chorionic-gonadatropin (HCG) a hormone that is ONLY released by a fertilized egg after it has implanted itself in the uterus (about 7 days after conception). BC pills only contain estrogen and progesterone, not HCG.

(Interesting side note: certain tumors in testicular cancer can also produce HCG, so one way of testing men for testicular cancer is by giving them a pregnancy test. So guys, if you ever get a positive on a pregnancy test, head to the doctor. )

What happens if I skip a pill?

The pill works best when taken at the same time every day, however, generally if you take it within 3 hours of when you normally take it, you'll be fine. So, if you normally take it at 9pm, but forget and take it at 11pm, you should be ok.

Any more than that, however, and a back up method is recommended. Here's a helpful chart I found from planned parenthood that explains what to do depending on how many were missed and at what point in the pack they were missed: http://www.plannedparenthood.org/health-topics/birth-control/if-forget-take-pill-19269.htm

How effective is the pill? And what does 99% effective mean exactly?

The pill is 99% effective, assuming perfect use. In the real world however, the overall "typical use" effectiveness rate is closer to 92%. This is when you factor in human error, medications that interfere with it's effectiveness, illness, etc.

Note that 99% effective does NOT mean that if you have sex 100 times, 1 of those times you'll get pregnant. It means that out of 100 women who take the pill perfectly, 1 of them will still get pregnant within 1 year of use. So in typical use, 8 out of 100 women will get pregnant within a year.

How soon does the pill become effective?

If you take it before Day 5 of your period, it's technically instantly effective. However, a general rule is to wait a month before you have unprotected sex to make sure no ovulation has occurred. Better safe than sorry.

What medications interfere with BC pills?

It's been said that antibiotics can interfere with BC pill effectiveness, but the only one to have a direct link to this was Rifampin (Rimactane). Generally, however, other antibiotics haven't been shown to lower the effectiveness.

St John's Wort is one herb that has been shown to effect the strength of a number of drugs, including BC pills. Do not take St Johns Wort if you're on the pill.

Certain anti-seizure drugs can effect absorption of the pill, such as Tegretol, Dilantin, and Topamax, among others. Depakote and Felbatol are 2 ani-seizure drugs that can increase the rate of hormones absorbed from BC, so let your doctor know if you are taking these or any other prescriptions, OTC or herbal medications for any reason.

Other meds you take may not effect the BC in terms of effectiveness, but can increase your risk of a blood clot, and therefore shouldn't be taken with BC.

Can alcohol, weed or other illegal drugs effect the pill?

Chemically speaking, no. Just don't get so stoned or drunk you forget to take it If you get drunk to the point of throwing up, however, see next question...

What if I'm sick while on the pill?

If you throw up within 2 hrs after taking the pill, chances are it wouldn't have absorbed, so take another one as soon as you can (treat it like a missed pill, follow instructions on the table on the link above) The same is true for severe diarrhea lasting more than 24 hrs. If you just have 1 or 2 loose stools, don't worry about it. Having a head cold also won't affect absorption.

I'm a teen and want to go on BC but don't want my parents to know I'm having sex. Can I get on it without their permission?

In the US, it depends on your state, unfortunately. (IMO all teens should have unrestricted access to it, but alas I'm not in charge) Here's a list of the laws in different states. http://www.contracept.org/minorsaccess.php

Because of the differences in health care systems, I'm not sure about the laws in other countries. Just remember--THERE ARE NO AGE RESTRICTIONS TO BUYING CONDOMS!!

Alternatively, you could convince your parents that you need them due to terrible, painful periods. You shouldn't have to do it that way, but c'est la vie.

Also, you do not need to get a pap smear to get on birth control, your family doc can put you on them, especially if you insist you're not sexually active. That being said, if you are sexually active, you should be getting regular pap smears.


Feel free to add any other questions you can think of. I'd be happy to answer them.