The best birth control is not only effective, but side effect free. Here is your guide to finding it.
We’ve all had that discussion with a friend or family member about how a given birth control method didn’t work for them, while someone else will swear by that same method. Maybe your best friend had a bad experience with the pill and has sworn off hormonal birth control, but you can’t imagine using anything else.
Given that there are nearly 200 birth control options in the US¹ it’s not surprising that choosing the right birth control is incredibly hard and confusing, with plenty of conflicting advice. And unfortunately, given the research medical gap² ³ (and the namesake of our blog!) that has not adequately prioritized research into individualized contraception choice, there is not a lot of evidence-based science that can point us to a clear answer to which birth control is best for a given individual. As is often the case, this leaves the door open for a lot of pseudoscience and is forcing people seeking contraception to rely on word-of-mouth and trial-and-error.
Here at adyn, our goal is to bring you our scientific perspective and clarity to this topic. It’s incredibly important, as birth control can have awful side effects, ranging from acne to life-threatening blood clots.⁴ Let’s start by outlining the types of birth controls currently approved and available in the US.
What types of birth control are available?
Birth control methods can be divided into two categories: hormonal and non-hormonal.¹ Non-hormonal birth control includes barrier methods such as male and female condoms or diaphragms, and other methods such as the copper intrauterine device (IUD) or the recently FDA approved non-hormonal vaginal gel Phexxi.
Hormonal birth control methods constitute the majority of birth control methods, including the:
We’ll go over each of the different types of hormonal birth control options that are out there, specifically in the context of what they contain, how they work, and how they are delivered.
Let’s start with some necessary background scientific terms that come up a lot when discussing hormonal birth control.
Hormones. A hormone is a chemical signal that your body uses as a messenger to coordinate biological processes throughout your body.⁵ For example, you’ve probably heard of progesterone, a hormone that plays a variety of roles in the menstrual cycle and in reproduction, including coordinating the preparation of the uterus for pregnancy.
The prevention of ovulation (the release of an egg from your ovary — without an egg for the sperm to fertilize, you can’t become pregnant)
Thickening of the mucus secreted by your cervix, which acts as a barrier and stops the sperm from reaching and fertilizing the egg.
Estrogens. Estrogens are a type of hormone that plays a role in reproductive development, the regulation of the menstrual cycle, pregnancy, and lactation . Estrogen in birth control is primarily present to help regulate bleeding, though it also prevents ovulation.⁴
All hormonal birth control methods include a progestin, and some include an estrogen, as well. The hormonal birth control methods work by delivering these biological signals to your body. Beyond their roles in reproduction, these types of hormones can also play roles in other biological processes in your body, including roles relating to body weight regulation, bone health, mood, and blood clotting. This is why hormonal birth control methods can sometimes have unwanted side effects.
The biggest noticeable difference among birth control methods is how the hormones are delivered to your body. A wide variety of options are available, and the delivery system can make a difference both in terms of efficacy and side effects, as well as your personal preference.
The Implant (Nexplanon). Let’s start with the implant. The implant is a small rod, about the size of a matchstick, that is inserted under the skin in your upper arm and releases a progestin. It’s more than 99% effective, meaning fewer than 1 out of 100 people using the implant become pregnant per year of use. For most people, it will also lead to lighter periods. You only have to get it replaced every 5 years.
The Shot (Depo-Provera). The shot is an injection of a progestin every 3 months. While it’s nice that you only do it once in a while, getting pricked isn’t for everyone, and visiting a provider every 3 months might not be possible/feasible for everyone. About half the people will stop getting their period while they are on the shot.
Though it is technically 99% effective, the reality is that we are all human, and not everyone is able to get to their three month appointment. So in reality, it is 94% effective (meaning 6 out of every 100 shot users will get pregnant each year of use). One important caveat to the shot is that it can take up to 10 months after stopping the shot to get pregnant.
The Hormonal Intrauterine Device (Hormonal IUD; Mirena, Kyleena, Liletta, and Skyla). The hormonal IUD is a T-shaped piece of plastic that is inserted through your cervix into your uterus, where it releases a progestin. Depending on the brand, it can last between 3 (Skyla) to 7 (Mirena, Liletta) years.
The hormonal IUDs usually make your periods much lighter, and some people stop getting their periods. All hormonal IUDs are 99% effective (meaning 1 out of every 100 hormonal IUD users will get pregnant each year of use).
Oral contraceptives. Oral contraceptives are pills that are taken every day and contain either a progestin alone (minipill) or a progestin with an estrogen (combination pill). The pill will usually make your period lighter and more regular. You can even use the combination pill to safely skip your period, though this should be done in consultation with your doctor. Some pills are even specifically designed to provide longer cycles, up to three months in duration.
We’ll cover the main differences between the combination pill and minipill in the next section, but they are both 99% effective if taken correctly. Though, as we’re all human, the real efficacy is 91% (meaning 9 out of every 100 pill users will get pregnant each year of use).
The Patch (Xulane). The patch is an adhesive patch that you can wear on your arm, belly, back or butt. It needs to be replaced once a week. The patch contains both an estrogen and a progestin, which are absorbed through your skin and into your bloodstream. The patch will usually make your periods lighter and more regular. You can also opt to skip your period altogether if that’s your preference, though this should be done in consultation with your doctor.
The patch is 99% effective if used as prescribed, but as with other methods, not everyone is going to be able to use it correctly all the time, so the reality is that it is effective 91% of the time (meaning 9 out of every 100 patch users will get pregnant each year of use).
The Vaginal Ring (NuvaRing, Annovera). The ring is a small and flexible ring that you wear inside your vagina. In contrast to the IUD, which is inserted by a healthcare provider, you can insert the ring yourself. The ring contains an estrogen and a progestin which are absorbed into your body through your vaginal lining. It needs to be removed every 3-5 weeks, and is left out for 1 week during which you will usually get your period. The NuvaRing needs to be replaced with a new ring, while the Annovera can be reinserted and lasts for up to a year.
The ring will usually make your periods lighter and more regular. You can also opt to skip your period altogether if that’s your preference, though this should be done in consultation with your doctor. The NuvaRing is 99% effective if used as prescribed, but the reality is that we’re all human, so the real efficacy of the NuvaRing is 91% (meaning 9 out of every 100 ring users will get pregnant each year of use).
A wide variety of oral contraceptives are available. The minipill only contains a progestin that is delivered at a low dose right at the threshold of efficacy  (this is why it must be taken at the same time every day!). Despite this, the typical failure rate of progestin-only pills is similar to that of the combination pill.
Combination pills (commonly known as “the pill”) include both a progestin and an estrogen. Estrogens can help inhibit ovulation, but their primary function in birth control is to help regulate bleeding. Unfortunately though, estrogens have been associated with some severe side effects in some cases, such as blood clots, so it may not be for everyone.
Different combination pills will also use different estrogens (remember, estrogen is a type of hormone, but there are different estrogens that can be used in contraceptives) and different amounts of estrogen in their pills. And while generic and brand-name drugs are marketed as interchangeable, it has been recognized that even pills that have the same active ingredients don’t always act the same ⁹.
In short, there are A LOT of options.
Okay, great! Now which one should I choose?
So now that we’ve reviewed the options, back to your question: Which birth control is the best birth control? The best birth control is the one that best works for you and is optimized for your body.
As you can see from the above description, there’s a lot going on with hormonal birth control. We’re using the body’s signaling system to prevent pregnancy. In some cases, hormonal birth control is also used to regulate or prevent periods, PMS, and menstrual cramps.
But because we’re regulating your body's hormonal and reproductive system — and everybody’s body is unique, has different baseline hormone levels and different reactions to different hormones, dosages and delivery methods — the best birth control is the one that works best for you.
A good way to think about it is in terms of food intolerance or allergies. Take peanuts, for example.
Some people enjoy peanut products on a daily basis, but for others, consuming peanuts can cause a wide range of unwanted symptoms . In some it can cause mild symptoms such as a runny nose, in others it can cause more bothersome symptoms like hives and itchiness, abdominal pain, and in some it can cause a reaction so severe it can lead to death if not treated immediately.
Why does the same exposure to peanuts lead to such different reactions? While scientists don’t know exactly why this happens, they do know that it’s due to individual differences in our biology¹⁰ and environment, including genetic differences.
These biological differences are also why you and your best friend can use the same birth control and have completely opposite experiences. Some birth control options are simply not a good fit for your body.
A very real and dangerous known example of this can be seen with blood clots. Some birth control methods, in particular those containing an estrogen taken orally, can raise the chances for a blood clot. If a person already has a genetic predisposition to form blood clots (in other words, their DNA is coded in such a way that increases this risk) taking the wrong kind of birth control can greatly raise the chance of blood clots¹¹. That same birth control method, though, can be completely safe for someone else.
Other severe side effects, such as cramps, bleeding, weight gain, depression, and worsened PMS can occur for some people using certain birth control options but not to others.
Is there a known process to finding the right one?
So, how do you figure out which birth control is best for you? Currently, the standard of care for birth control is the CDC Medical Eligibility Criteria¹². Basically, these criteria entail a series of questions that lead to a recommended birth control.
This is often combined with a trial-and-error approach during which your doctor will start you on a birth control method, and if it has a bad effect on you, you can then try the next one until you find one that works for you. Ideally, your doctor would be able to run genetic tests and collaborate with you to find the best birth control for your biology. Unfortunately, testing for common genetic risks for birth control side effects isn't routinely included in selecting a birth control yet.
So, to answer our question — the best birth control for you is the one that is optimized for your body, your genetics, and your preferences.
Ayal is a bioinformatician at adyn. He is interested in how genetics can influence a person's response to birth control, and how that knowledge can be used to provide people who use birth control with a better experience.
Katya Rubinow, M.D., is a board-certified endocrinologist and translational investigator. Her clinical and research interests include diabetes, women's health, cardiometabolic disease, sex steroids, and lipoprotein metabolism.