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How Common are Birth Control Side Effects?

Kristin Hall

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 2/5/2021

Spend a few minutes reading the leaflet that comes with birth control pills like Yaz, Estrostep or Ortho Tri-Cyclen and there’s a chance you’ll come away with the impression that hormonal birth control is, to put it lightly, a little dangerous.

First, there are the common side effects, which can range from nausea to weight gain, spotting and breast tenderness. 

Then there are the less common side effects, which can range from high blood pressure and sleep issues to serious, life-threatening medical events like blood clots.

The reality of birth control is that while side effects can and sometimes do happen, birth control pills are very safe for most women. Serious side effects from the pill are rare, and the majority of women will only experience minor side effects, if any at all.

Below, we’ve looked at how common side effects are from hormonal birth control pills. Our list covers everything from minor side effects such as spotting and weight gain to far less common, more serious side effects such as blood clots, hypertension and stroke.

The Most Common Birth Control Side Effects

Not all birth control pills use the same formula, meaning there’s no one-size-fits-all formula that applies to side effects for every type of hormonal birth control.

Most birth control pills contain a mix of an estrogen (typically ethinyl estradiol) and a progestin hormone. These hormones work together to stop ovulation, preventing you from releasing eggs and reducing your risk of becoming pregnant.

There are also progestin-only birth control pills, or “mini pills.” These pills only use a progestin hormone and don’t contain any ethinyl estradiol.

Because of these different formulas, your risk of experiencing side effects of birth control can vary depending on which pill you use. Despite this, there are several side effects that can occur with all birth control pills, from combined pills to progestin-only mini pills.

Intermenstrual Spotting

Intermenstrual spotting, or bleeding between periods, is one of the most common side effects of the birth control pill. It usually occurs within the first three months of using birth control and tends to resolve on its own.

Spotting is a normal side effect of using birth control. It’s usually not worth worrying about. If you have taken birth control for longer than one week, it will still be effective at preventing pregnancy while you’re experiencing spotting.

Most of the time, spotting resolves itself within two to three days. If your bleeding feels unusually heavy and continues for three or more days, or is mild but continues for more than five days, it’s best to contact your healthcare provider.

Spotting is a common side effect of birth control. In one study, 24% of women given a combined birth control pill containing lynestrenol and ethinyl estradiol experienced spotting during the first three months of use. This rate decreased to four percent over the course of the study.

If you’re experiencing spotting from birth control, it’s best not to panic. Most of the time, spotting goes away on its own, just like in the study linked above. If it doesn’t, contact your healthcare provider. They can help you switch to a form of birth control that doesn’t cause this side effect.

Breast Tenderness

Breast tenderness is another common side effect of birth control pills. The hormones used in both combined and progestin-only birth control pills can stimulate your breast tissue, causing everything from minor discomfort to enlargement of your breasts.

Like spotting, your risk of experiencing your breast tenderness is highest during the first few months of using birth control. During this period, your body is still adjusting to the hormones used in your birth control pills and tends to be the most sensitive to potential side effects.

Breast tenderness normally resolves on its own. However, some women experience ongoing discomfort in their breasts. If your breasts still hurt after more than a few weeks, contact your healthcare provider so that you can discuss the issue.

In some cases, birth control can also cause lumps to form in your breasts. These are usually benign (60- 80% of all breast lumps are non-cancerous). If you feel a lump in your breast after you start using birth control, the best thing to do is to contact your healthcare provider.

Finally, it’s important to point out that birth control is not linked to a significant increase in your risk of developing breast cancer. 

Studies have consistently shown that your risk of developing cancer from modern birth control pills is extremely low, however, if you have a concern please contact your healthcare provider for evaluation.

Weight Gain

Ever panicked when you stepped onto the scale after starting birth control? The hormones used in birth control pills may cause a mild increase in your weight, especially during the first weeks of using hormonal birth control.

This doesn’t affect everyone who uses birth control. In fact, a detailed analysis of studies of birth control side effects shows that most women who use birth control don’t see any change in their weight or body composition.

Usually, any weight gain from birth control pills is caused by your body retaining more fluid than it normally would. Estrogens and progestins, which are used in combined birth control pills, can cause your body to retain more fluid, particularly in your breast tissue and around your hips.

This weight gain can happen fairly quickly, often within a few weeks of you starting to use birth control pills.

If you’ve noticed your weight creeping upward after you started using birth control, it’s best not to panic. Assuming you haven’t increased your calorie intake, the weight gain is most likely just a result of your body retaining more water than it normally would.

Studies show that the average amount of weight gained from birth control is around 4.4 pounds after six to 12 months of use. It is important to note that this study only took a look at progestin.

This weight gain is often temporary, meaning you’ll retain more water as your body gets used to the hormones used in your birth control pills. Small changes to your diet, like avoiding salty food, can often be enough to reduce the amount of fluid your body retains.

All in all, it’s best not to worry about this one. With the exception of Depo-Provera (the hormonal birth control injection), birth control usually isn’t linked to any increase in body fat, meaning any weight you gain without increasing your calorie intake is probably just extra water.

Light or Missed Periods

Missed your period after starting birth control? You’re not alone. Many women occasionally miss a period after they start using hormonal birth control, a side effect that’s typically caused by how extra progestins and estrogen affect your menstrual cycle.

Because hormonal birth control stops your ovaries from releasing eggs, your uterus no longer needs to produce a protective lining. This gives you a lighter, often very mild period that might not even come at all.

Birth control pills can also speed up or delay your period. Some women get theirs a little early after starting birth control (the normal range is 21 to 35 days), while others experience a period that’s shorter or longer than normal.

While it’s quite normal to have an extremely light period on birth control (sometimes you might not experience any flow at all), it’s still worth taking a pregnancy test before you start your next cycle if you don’t notice any bleeding at all.

Like many other birth control side effects, this one is most common during the first few months of using hormonal birth control. After three to six months, you’ll normally have a consistent and predictable period that starts at the same time every cycle.

It’s also worth noting that other factors can affect your period, not just birth control. If you’ve felt stressed, made changes to your diet or started using any other prescription medications, these factors could all have an effect on your period.


Have you noticed an upset stomach after you started birth control? The hormones used in birth control pills—in particular, ethinyl estradiol—can contribute to feelings of nausea, giving you an urge to vomit or use the toilet once you start taking birth control pills.

These feelings can occur temporarily after you take each pill or persist throughout the day as a general side effect.

Like other birth control side effects, nausea is usually temporary. It’s most common during the first two to three months of using birth control pills and usually subsides on its own. It tends to be more severe with emergency contraceptives such as Plan B than with regular birth control.

There are several ways to make nausea from birth control pills easier to tolerate. The first is to only ever take your birth control with food. This means your body will have something to digest at same time as it’s metabolizing the hormones inside the birth control pill.

The second is to take your birth control pill at night. Many women notice that taking the pill at nighttime makes nausea easier to deal with, especially since you’re less likely to be awake as the symptoms peak.

If you opt to take your birth control pills before going to bed, it’s important to stick to a consistent daily schedule. Most birth control pills are only 99% effective if you take them within three hours of the same time every day.

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Less Common Birth Control Side Effects

Birth control pills can also cause several less common side effects. These include a decrease in your sex drive, mood changes and even migraine headaches. For a small percentage of people, birth control pills can even have an effect on your eyes.

We’ve listed these less common side effects below, along with the available scientific data on why each side effect happens and how common it is.

Headaches and Migraines

Although it’s uncommon, the estrogen and progestin hormones in birth control pills can trigger headaches and migraines in some people.

This side effect was more common in the past than it is now, as older-generation birth control pills used higher doses of estrogens and progestins. Today’s combined birth control pills use a relatively low dose of each hormone, reducing your risk of experiencing side effects.

Still, it’s possible to experience the occasional headache after you start using birth control. Like many other birth control side effects, headaches are caused by fluctuations in your body’s level of progestin and estrogen hormones, both of which are used in combined birth control pills.

This is also why many women experience headaches during their period. On your period, your body’s estrogen levels can fluctuate, giving you a higher risk of experiencing a hormone-induced headache.

If you’ve noticed occasional non-migraine headaches after starting birth control, the best way to reduce their severity is to take your birth control pill at the same time every day. This can help to even out your hormone levels and prevent the sudden fluctuations that can cause headaches.

It’s also important to take general headache prevention precautions. Make sure you sleep well, avoid sources of stress, limit your alcohol consumption and stay hydrated, especially after you start using birth control.

If you get migraine headaches after starting birth control, it’s important that you let your healthcare provider know as soon as possible. Migraines can indicate that you may have a higher stroke risk from hormonal birth control, making it important to talk to your healthcare provider about safer alternatives.

Your healthcare provider might recommend switching to a safer, alternative form of hormonal birth control, or using a non-hormonal method of contraception.

Mood Changes

The progestin and estrogen hormones used in birth control pills can affect your mood, causing you to experience mood swings. Like other uncommon birth control side effects, this tends to only affect a small percentage of women who use birth control.

Your body’s levels of estrogen and progestins fluctuate on their own, usually over the course of your menstrual cycle. When you start using birth control, the higher levels of these hormones in your body can make it easier to become annoyed, sad or angry.

This is because hormones have a real, noticeable effect on your mood. Studies show that progestin hormones can induce irritability, depressed mood and anxiety when given to women as part of a hormone replacement therapy (HRT) treatment.

In short, the hormones in birth control probably won’t affect you, but if they do, they could make you feel more easily annoyed, depressed, anxious or angry than normal.

Of course, these are completely normal emotions that you’ll experience regardless of whether or not you use hormonal birth control. But if you notice yourself feeling sad, angry or annoyed after you start taking the pill without any obvious reason, it could be the result of your hormones.

According to studies, mood changes affect four to 10 percent of women who take hormonal birth control pills. Just like headaches, this is another uncommon but potentially serious side effect of that’s worth looking out for.

As always, if you experience mood changes after you start using birth control, it’s best to talk to your healthcare provider. These side effects can often be minimized or avoided by switching to a different pill, or by using a non-hormonal form of contraception.

Reduced Sex Drive

Birth control can have mixed effects on your libido. Some women notice an increase in sexual desire after they start taking birth control. However, it’s more common to experience a reduced level of interest in sex.

Like the other side effects in this section, a reduced sex drive from birth control isn’t a common problem. Most women who use birth control don’t notice any difference in their level of sexual interest, be it an increase or a reduction.

The key reason birth control can affect your sex drive is its impact on androgens. Birth control pills work by reducing your body’s production of androgenic hormones like testosterone, which plays an important role in regulating your sex drive.

Testosterone is also one of the main hormones that can cause acne, which is why some birth control pills are approved by the FDA as acne treatments.

For some women, this can cause a noticeable reduction in your interest in sex, as well as your level of desire for sexual activity.

On the whole, a reduced sex drive from birth control pills is fairly rare. Studies also show that it’s rare for birth control to affect libido, with the exception of the Depo-Provera injection.

If you’ve noticed a lower sex drive after you started using birth control, the best option is to talk to your healthcare provider. 

Switching to a different type of birth control pill (such as a progestin-only pill) or using a non-hormonal form of contraception can often help to reverse this side effect.

Eye Changes

Although it’s very rare, it’s possible for birth control pills to cause some minor changes to your eyes.

While there’s no evidence linking birth control pills to eye disease, the hormones used in birth control pills can lead your cornea (the clear layer at the front of your eye) to thicken. If you use contact lenses, this means that they might not fit after several months of using birth control.

If you notice your contact lenses becoming uncomfortable or failing to properly fit, make sure you let your ophthalmologist know that you’ve started taking hormonal birth control. They’ll be able to switch your contact lenses to larger ones that provide a more comfortable fit.

The hormones in birth control pills can also slightly increase your risk of experiencing dry eye syndrome (DES) with people who wear contact lenses. This can cause your eyes to feel itchy and uncomfortable. It can also cause your vision to become blurred and less defined than normal.

As always, the best way to deal with dry eye syndrome is to talk to your healthcare provider. Let them know you’ve started using birth control and explain your symptoms. Your healthcare provider might be able to give you an alternative form of contraception that doesn’t cause this side effect.

Like mood changes, headaches, and a reduced sex drive, dry eyes or corneal changes are all rare side effects of birth control. In one study, researchers stated that the risk of vision-related side effects from birth control is as low as one in 230,000.

In short, unless you’ve noticed symptoms of dry eye syndrome or struggled to comfortably fit your contact lenses, you probably don’t need to worry about this potential side effect.

Rare, Serious Side Effects of Birth Control

Overall, birth control pills are extremely safe. Tens of millions of women use them without any significant issues in the US alone, with hundreds of millions of safe, healthy birth control users worldwide.

Despite this, it is possible for birth control pills to cause potentially serious side effects. These side effects are mostly cardiovascular in nature and occur rarely, usually in people with certain lifestyle or genetic risk factors. These risks increase in women over the age of 35 and who smoke. 

Below, we’ve listed the most serious potential side effects of hormonal birth control, as well as any relevant scientific data on how these side effects occur, how frequently they occur and the key factors that can contribute to them.

Blood Clots and Deep Vein Thrombosis (DVT)

Blood clots from birth control pills are rare, affecting about 12 in every 10,000 women who use oral contraceptives, depending upon the type of birth control pill you take. Deep vein thrombosis, a blood clot that affects veins deep inside the body, is also rare, affecting three to nine out of every 10,000 women on birth control annually.

Despite this, blood clots can and sometimes do happen to women who use birth control. Your risk of experiencing a blood clot from using birth control is higher if you smoke, with smokers aged 35 or older the highest risk group.

The possibility of a blood clot from birth control tends to increase the more you smoke, meaning every additional cigarette increases your risk. Our guide to smoking and birth control covers this topic in more detail, as well as other smoking-related health risks for birth control users.  

Because of this, your healthcare provider will usually recommend an alternative form of contraception if you smoke, particularly if you’re 35 or older.


Although birth control pills don’t cause strokes directly, they can potentially increase your risk of suffering a stroke in certain situations.

Overall, the risk of experiencing a stroke as a result of using birth control is extremely low. More than 100 million women safely use birth control worldwide, with only a tiny fraction of active birth control users suffering from strokes and other serious health issues.

According to current research, using birth control increases your risk of having a stroke to approximately 1.9 times the standard level.

On average, approximately 4.4 women out of every 100,000 women of childbearing age suffer ischemic strokes every year. Women who use birth control pills have a slightly higher risk, with approximately 8.5 strokes every year per 100,000 women of childbearing age.

While this figure might look alarming, it’s important to put it into context. Your risk of suffering a stroke as a result of using birth control is very small. About 10.6 people per 100,000 die in auto accidents every year, while 115.8 people in every 100,000 die from coronary artery disease.

In short, while a 90% increase in stroke risk can seem like a serious cause for concern, the tiny percentage of childbearing age women who experience strokes in the first place means this isn’t a reason to avoid birth control.

With this said, there are several factors that can contribute to a higher stroke risk. If you’re aged 35 and up and regularly smoke cigarettes, you should not use birth control. People in this group have the highest risk of experiencing stroke and other cardiovascular issues from birth control.

If you’re concerned about the stroke risk from birth control, the best option is to discuss it with your healthcare provider. They’ll be able to put birth control’s cardiovascular health risks in context so that you’re more informed and capable of deciding whether birth control pills are right for you.

Learn More About Birth Control

Overall, birth control is a safe, effective way to prevent pregnancy. Most birth controls are 99% effective when used correctly, with side effects—aside from common issues such as spotting and nausea—fairly uncommon.

Our guides to Yaz, Estrostep and Ortho Tri-Cyclen explain how three of the most widely used combined birth control pills work. You can also learn about progestin-only pills in our guide to the differences between combined birth control and “mini pills.”

Interested in using birth control to treat hormonal acne? Our guide to birth control pills and acne explains how combined birth control pills like Yaz, Estrostep and Ortho Tri-Cyclen can help you prevent acne outbreaks and improve your skin.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

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