How Effective is Birth Control?

By Zina Semenovskaya, MD
Medically reviewed checkmarkMedically reviewed
March 14, 2022

In the United States, 65% of individuals use some type of birth control throughout their reproductive years (age 18-49).

The Centers for Disease Control and Prevention (CDC) reports that birth control pills are one of the most commonly used forms of contraception, used by 14% of people.

The birth control pill is a generally safe, affordable way for people to prevent unwanted pregnancies. 

There are two types of birth control pills: combination pills that contain estrogen and progestin and the minipill, which contains progestin only.

Combination pills are the more commonly used pills, but the minipill is a good choice for those who cannot take estrogen due to health issues, like cardiovascular disease or a history of stroke. 

In this article, we’ll review the effectiveness of birth control.

We’ll discuss the factors that impact how effective the various birth control methods are, which method is most effective and why, and how long it takes for birth control to work.

Birth Control Effectiveness 

The chart below explains the different forms of birth control, their effectiveness with the range of typical-to-perfect use, how often they should be taken or replaced, and how each method should be used for maximum protection.

Birth Control MethodEffectivenessHow Often Taken or Replaced and How Used
Sterilization for men99% or moreOne in-office procedure
Sterilization for women99% or moreOne surgical procedure
ParaGard copper IUD99% or moreReplace in 10-12 years
Mirena hormonal IUDLiletta hormonal IUD99% or moreReplace in 5-7 years
Kyleena hormonal IUD99% or moreReplace in five years
Skyla hormonal IUD99% or moreReplace in three years
Progestin injection94% or moreInjection every three months—some people learn to do injections themselves
Contraceptive arm implant99%New implant needed every three years
Oral contraceptives:Monophasic or multiphasic91% or more based on consistency of useTake every day for three weeks,  then take placebo pills for one week
Hormone patch91% or more based on consistency of useApply a new patch to your body each week on the same day for three weeks in a rowRotate location on skin to avoid irritationTake one week off
Vaginal ring91% or more based on consistency of useRemove ring every three weeks and replace it one week later
Vaginal sponge76%-91% Insert in vagina up to 24 hours before intercourse
Diaphragm 71%-98% with spermicideMust be inserted with spermicide no more than six hours before intercourse
Cervical cap 71%-98% with spermicideMust be inserted with spermicide no more than six hours before intercourse
External condom82%-98% Must be put on before intercourse and stay on throughout
Internal condom79%-95%Must be inserted before intercourse and remain in place throughout

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Factors that Influence Birth Control Effectiveness

There is no single method of birth control—even sterilization—that is guaranteed to be 100% effective, but certain factors can increase or decrease the level of effectiveness for some forms of birth control. 

Both partners in a sexual relationship need to be vigilant about using their chosen method of birth control every time they have sex to reach the highest level of effectiveness.

Additionally, using two or more methods of birth control will increase their effectiveness.

Long-Acting Reversible Contraceptives

Although no birth control method is 100% effective, long-acting reversible contraceptives (LARCs), such as intrauterine devices (IUDs) and implants injected under the skin, are far less likely to fail than other methods.

This is because the user doesn’t have to do anything for those products to work once they are inserted in the vagina or implanted in the arm. 

LARCs include hormonal and non-hormonal forms of birth control. For example, Mirena is a hormonal IUD, whereas ParaGard is a non-hormonal IUD.

Other Hormonal Methods  

The birth control pill—just like any other birth control that isn’t a LARC—is up to 99% effective, depending on the consistency of use.

The pill must be taken every day, without any missed days, to reach maximum effectiveness.

The same level of responsible use is needed for the other hormone-based birth control methods, including the patch and the vaginal ring. 

For most users, it is common to miss a day or two each month, making the pill approximately 91% effective at preventing pregnancy.

It’s for this reason that many physicians recommend long-acting birth control options for young people under the age of 18 who may have trouble remembering their scheduled pill doses or patch or ring replacements. 

Be aware that some antibiotics can reduce the effectiveness of the birth control pill.

Ask your doctor about this if you are prescribed antibiotics while taking the pill.

Barrier Methods

It’s important to understand that barrier methods of birth control, including diaphragms, cervical caps, and condoms, have to be used not only every time there is sexual intercourse, but also with the correct spermicide and within the right time frame.

For example, you can’t insert a diaphragm more than six hours before sex because the spermicide will not work as effectively.

It also must remain in place for six to eight hours after sex to prevent pregnancy. 

Condoms must stay in place for the entire sexual encounter as well. 

Diaphragm and cervical cap users should be checked by their physicians every year to ensure their method of birth control still fits properly.

Doing so will offer the best protection they can get from unwanted pregnancy.

When used correctly versus incorrectly, the difference in failure rates for barrier methods can be as high as 17%. 

Which Method Is Most Effective?

Statistically, the most effective methods are sterilization and LARCs, which each have 99% reliability for protection.

Still, sterilization is permanent, and many people choose not to commit to a long-acting reversible contraceptive, since they may decide to have children soon or prefer not to use an implanted device. 

All other birth control methods are potentially over 90% effective if used reliably and correctly. 

The birth control pill, patch, or vaginal ring offers hormonal protection from pregnancy by preventing ovulation.

The birth control pill and the other hormonal options have to be used as prescribed, or there’s a higher chance of failure.

Overall, however, the pill is highly reliable at a 91% prevention rate when used as most people typically do.

Barrier methods, including the diaphragm, cervical cap, or sponge, are used with spermicide to kill the sperm before they reach the cervix and create a barrier to protect the cervix from the sperm entering it to fertilize the egg.

Barrier methods can fail if they are dislodged from their place in the vagina or if there’s insufficient spermicide.

Also, if they’re removed from the vagina too soon, it can result in pregnancy. However, when used correctly and as most people typically use them, barrier methods are 90% effective.

Some people will develop urinary tract infections (UTIs) due to the spermicide used with barrier methods.

You may need to try different brands if this happens to you, and be aware that there are different types of spermicides which you may or may not have a sensitivity to.

Condoms prevent sperm from entering the vagina because of the impenetrable material used to make them.

They also offer protection from sexually transmitted diseases, which no other birth control methods do.

But using condoms for birth control is far less secure than other methods for a variety of reasons, including:

  • Condoms can break
  • Condoms may not always be available when sex is initiated
  • Some people find condoms uncomfortable and may resist wearing them
  • Condoms are sometimes removed too soon

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How Long Does it Take for Birth Control to Work?

Birth control start working at different times depending on when you start it and which oney you’re using.

For example, suppose you start taking the combination pill within five days of your period starting.

In that case, you’ll be protected within five days.

So if your period starts on a Monday and you begin taking the pill five days later on Saturday, you’ll be protected the following week on Thursday.

If you’re taking the minipill, you’re protected after 48 hours.

The vaginal ring or patch takes five to seven days to begin protecting you from pregnancy.

The LARC methods vary slightly: Hormonal IUDs and implants are effective immediately if they are inserted or implanted within five days of your period starting.

Otherwise, they take five to seven days to start working. Non-hormonal IUDs (ParaGard) are always effective immediately.

If you want to explore your birth control options, did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a provider in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

How effective is birth control without pulling out?
If you're using withdrawal as your primary form of birth control and can do it perfectly every time, your chances of getting pregnant are less than four percent. But, since that's very hard for most people to do, the actual pregnancy rate for the withdrawal method is 22 pregnancies out of 100.
How likely is it for birth control to fail?
The likelihood of failure for most methods depends on the responsible use of birth control by the sexual partners. If you use birth control as prescribed or recommended, it can be up to 99% effective in most cases.
Is the pill better than condoms?
The pill has a lower average rate of pregnancies than condoms do, making it the safer choice for preventing pregnancy. But the condom offers protection from sexually transmitted diseases. So the best, safest option would be to use both.
Can you get pregnant while on birth control?
Yes. Even permanent sterilization can, in very rare cases, result in pregnancy. For example, in the case of tubal ligation (sterilization for women), one out of 200 people will become pregnant.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Zina Semenovskaya, MD

Dr. Semenovskaya specializes in emergency medicine, and received her medical degree from Weill Cornell Medical College. She is currently the medical director at Remote Emergency Medicine Consulting, LLC and splits her time working clinically as an emergency medicine attending in California and Alaska. She is the first of our doctors to be fluent in Russian.