How Do Birth Control Pills Work

Dr. Jolene BrightenPublished: Last Reviewed: Birth Control Leave a Comment

I don't know about you, but I wasn't told how the pill worked until my final years on it. And what did I care? I just didn't want painful periods or a baby and the pill promised to deliver on both accounts. But I had to wonder as I entered medical school, “just how do birth control pills work?”

And it is one of the top questions I get from readers and patients.

How Do Birth Control Pills Work

There are a couple of options when it comes to the pill—combination and progestin-only. The combination pill contains both synthetic estrogen and progesterone (more accurately progestin). And the progestin-only is exactly what it sounds like and does not have estrogen. How does the pill work? By suppressing the signals from your brain to your ovaries and altering natural function of the reproductive system.

Combination Oral Contraceptives

This is the most commonly prescribed type of birth control because it has a better rate of pregnancy prevention.

There are several ways in which the best birth control prevents pregnancy. The number one way is to prevent ovulation.

Birth Control Pills and Ovulation

By taking birth control tablets you send a signal to your brain that there are enough hormones and no need to make more. Your brain in turn does not secrete hormones and the ovaries receive no signal to make hormones.

The pill specifically suppresses hypothalamic gonadotropin-releasing hormone (GnRH) and pituitary gonadotropin secretion. These are brain structures that control hormone production. The suppression of these hormones results in luteinizing hormone (LH) suppression. Without LH your ovaries don't get the signal to ovulate. So, no egg is released.

This is where the combination pill shines and the progestin-only pills can fail.

In theory, the pill should shut down follicle stimulating hormone (FSH) as well, but in some women, they continue to develop follicles.

Progestin-Only Birth Control

Because the typical pill also contains progestin, the following also applies to the combination pill. If you're taking progestin-only then know that there is a different mechanism at play.

Progestin-only is typically used in women with high risk of stroke, like in early postpartum.

Changes to Endometrium

Progestin makes the endometrium (lining of the uterus) less favorable for an embryo to implant. So yes, you could have a situation where a sperm fertilizes the egg, but the egg fails to implant.

Changes to Cervical Mucus

Progestin causes changes in cervical mucus so it is much more difficult for sperm to swim and make it to the egg.

Changes to Tubal Motility

The pill may also alter how your female reproductive tract functions in terms of escorting the egg to meet sperm.

It has been estimated that about half or more of women ovulate while using progestin-only contraception.

Does The Pill Balance Hormones?

Ok, so you now know that the main mechanism of birth control is to shut down your natural hormones. With that in mind, how could the pill fix a hormone imbalance when it is preventing you from making hormones in the first place?

The truth is, the pill will not fix your hormone imbalance, your periods, your acne, your PCOS…it will NOT fix your hormones.

Every day in my medical practice I hear from women who have been told that taking hormonal birth control is not only THE solution to her hormonal problems, but it's the ONLY solution if she wants to “fix” her hormones. That's B.S.

Here's the deal, that pill, patch, IUD (fill in the blank) suppresses your hormones. It tells your brain to stop talking to your ovaries and your ovaries that they've been replaced. And while it can strong-arm your body into submission and make those symptoms be gone, it is a short-term (and short-sighted) solution to your hormone struggles.

Those symptoms that you hate? That we all hate. Yeah, well they are your body giving you some serious data that can help you fix your own period and make your menstrual cycle work for you.

If you're looking for a root cause approach to your health and breaking free from hormonal birth control then grab my free guide on hormonal birth control and take back your body!

And if you are using the pill for pregnancy prevention and feel it is your best option, my guide will support you too. Because the birth control side effects are real and you need to take special steps to support your body.

And The Birth Control Side Effects Are Real

I was passed the pill with zero discussion about how it could impact my health. At the time of starting the pill I was told my daily habit had a 10-year expiration date. Ten years came and my doctor shrugged it off and told me that having a baby was far too big of a risk.


I was in medical school and any doc reading this right now comprehends the level of debt you incur in year one alone. A baby + graduating + student loan debt + career…yeah, my doc was right. The math just didn't add up. And a baby wasn't in the cards at this time.

But what my doctor failed to mention is that when I gave up pills to prevent pregancy…I could find myself in a state of hormonal hell, also known as Post-Birth Control Syndrome (PBCS).

Thank god I had a background in nutritional biochemistry and was in naturopathic med school. Can't even imagine if I hadn't. No, wait. I can. Because these are the women who come into my clinic every week.

Here's what doctors should tell the millions of women prescribed hormonal birth control

Here's a list of some of the side effects you can find in medical databases, package inserts, and that many clinicians have observed in their patients. This list isn't meant to scare, but to put you in the know. And if you're feeling fearful about the side effects, post-birth control syndrome, or your options, know there is a lot you can do to care for your body. I've helped thousands of women protect their body on the pill, transition off successfully, and reverse PBCS.

Before you pop that pill please know the side effects.

Compromised Gut Health

Hormonal birth control messes with your gut. BIG time! Leaky gut, microbiota (good gut bugs) imbalance, trigger autoimmunity. It is no joke in this arena.

Clots, Stroke and Heart Attack

Birth control can trigger clots, strokes and heart attacks…especially if you're over 35. Um, I don't even want to tell you how many of 35+ year old patients of mine have been told to just use hormones until menopause. Just NO.

Metabolic Health

It messes with your metabolism, which can lead to weight gain, blood sugar imbalances, and diabetes.

Adrenal and Thyroid Disease

It's a thyroid hater like no other. Read more about thyroid and birth control here.

Adrenals. Yeah, forget them. Synthetic hormones be hate'n on them like cray. I’ve detailed the effect on adrenals in this article.

Anxiety, Depression, and Suicide

Your mood? Oh, girl. Just get a pint of ice cream, get in those comfy pants and cry until your heart's content. Wait, you're done crying? Great! Get really scared about everything and bring on the anxiety! #moodswings

The majority of my patients report some change in their mood when they start the pill. If you're experiencing changes like new onset anxiety, depression or lack of motivation, please meet with your doctor.

You can read more about the negative effects of birth control on your mood in this article.

Nutrient Deficiencies

Because birth control depletes key nutrients you can find yourself deficient in magnesium, B vitamins, zinc, and antioxidants. This is why I recommend women on the pill or with a history of it use a quality prenatal to support their health.

And this is all the tip of the iceberg. In my book, Beyond the Pill, I go into detail on all the ways the birth control pill can and does wreck your health if you're not actively safeguarding against the side effects. But you’ll also learn how to stay safe while you’re on it, how to effectively transition off, and the exact steps you need to take to reverse PBCS. 

On the Pill. Off the Pill. What Next?

My doctor didn't tell me any of this. And based on my patient population I'd bet you didn't get the low down on this before they wrote you that Rx. 

So what next? Get informed on how to support your body. You can grab my free birth control guide that will outline what you can do to protect your body now and in their future.

When it comes to your body, you deserve to be informed.

Please share this article with women who need support. Together, we can help transform women's health for the better.


Association of Hormonal Contraception With Depression

Occurrence of menses or pregnancy after cessation of a continuous oral contraceptive

Oral contraceptive discontinuation: a prospective evaluation of frequency and reasons.

Ovarian activity during regular oral contraceptive use

Ovarian follicular development is initiated during the hormone-free interval of oral contraceptive use

Ovulation incidence with oral contraceptives: a literature review

Post-“pill” amenorrhoea–cause or coincidence?

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About The Author

Dr. Jolene Brighten

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Dr. Jolene Brighten, NMD, is a women’s hormone expert and prominent leader in women’s medicine. As a licensed naturopathic physician who is board certified in naturopathic endocrinology, she takes an integrative approach in her clinical practice. A fierce patient advocate and completely dedicated to uncovering the root cause of hormonal imbalances, Dr. Brighten empowers women worldwide to take control of their health and their hormones. She is the best selling author of Beyond the Pill and Healing Your Body Naturally After Childbirth. Dr. Brighten is an international speaker, clinical educator, medical advisor within the tech community, and considered a leading authority on women’s health. She is a member of the MindBodyGreen Collective and a faculty member for the American Academy of Anti Aging Medicine. Her work has been featured in the New York Post, Forbes, Cosmopolitan, Huffington Post, Bustle, The Guardian, Sports Illustrated, Elle, and ABC News. Read more about me here.