How Does an IUD Work? All You Need to Know About This Birth Control Method

Women considering their birth control options should take IUDs into consideration. They are among the most expensive options out there, but they are also extremely effective and can be used in combination with other methods.

IUDs are considered safe for healthy women and last a long time. The best thing about them is that they don’t affect a woman’s ability to stay pregnant after they’ve been removed. Keep reading to find out how does an IUD work, how safe it is, how long it can protect you, and much more.

What Is an IUD?

An IUD is a contraceptive device that’s inserted into a woman’s uterus. The acronym stands for intra-uterine device, though the device is also commonly referred to as coil. It is one of long-acting reversible control (LARC) contraception methods and some women use it in combination with other methods.

At the moment of this writing, there are five brands of IUDs on the American market. Skyla, Mirena, Kyleena, and Liletta are hormone-based. They release small quantities of progestin, the hormone that’s used in many birth control pills, into your uterus. The fifth brand, ParaGard, is hormone-free. Instead, it uses copper to trigger your body to prevent pregnancy.

How Does It Work?

So, how does an IUD work? The hormone-based variety works the same way as a birth control pill. It releases small amounts of progestin into your uterus, preventing sperm from fertilizing eggs. With the hormone-based variety, periods stop completely after a while, making it almost impossible to stay pregnant. Periods in women who use hormonal IUDs go back to normal quickly after the device is removed.

On the other hand, the copper variety changes the chemical makeup of your uterus, thus triggering your immune system to prevent pregnancy. The copper in which these devices are wrapped is very efficient at preventing sperm from reaching the eggs. A copper device doesn’t diminish your ability to get pregnant and doesn’t affect it once removed.

Non-hormonal devices are effective immediately. A hormone-based device starts working immediately if it’s installed during your period. However, if it’s installed between periods, it might take up to a week to start working.

How Do You Insert It?

The doctor will insert an IUD during a regular office visit. While you’re lying on the table, the doctor will insert the speculum into your vagina to keep it open. They will then place the device into a tube and insert the tube into your vagina. The doctor will then eject the device from the tube and into the uterus. Once the IUD is in place, they’ll pull the tube out and remove the speculum. A pair of strings will hang from the device 1-2 inches down your vagina.

You might experience pain and bleeding during the procedure. They usually go away in a few days. Pain can cause some women to feel lightheaded. If you experience pain, you might want to take some over-the-counter (OTC) pain medication.

If the device starts coming out at some point, it should be removed and a second device should be inserted. The removal is also done by your doctor.

Can It Fall Out?

The chances of your IUD falling out are slim. However, the likelihood may increase if:

  • You’re under 20
  • Haven’t had kids
  • The IUD was inserted right after you had a baby
  • Your uterus is of unusual shape or size
  • There are fibroids in your uterus

How Long Does It Work?

How long an IUD works depends on the brand you choose to use. For example, Skyla and Liletta devices work for 3 years, while Mirena and Kyleena are effective for 5 years. On the other hand, ParaGard devices can protect you for 10 years.

How Effective Is an IUD?

IUDs are among the safest and most effective birth control methods. The rate of failure is less than 1%. The copper-based ParaGard devices have a 0.8% failure rate in the first 12 months. The remaining four brands have an average failure rate of only 0.2%.

Have in mind that you can use the copper devices to prevent unwanted pregnancy even after you’ve had unprotected sex. The device should be inserted within five days, though the faster you insert it, the more effective it will be.

On the other hand, male contraception methods are not as reliable. While male sterilization works in 99.85% of cases, condoms, which may be more comfortable than an IUD, have a not-so-comfortable failure rate of 15%.


Although less popular than condoms and birth control pills, IUDs come with a wide range of benefits.

For one, an IUD device lasts a long time once it is inserted. You typically check up on it when you take your regular gynecological exams. Also, these devices don’t require any maintenance.

An IUD device is a one-time expense. Though it might be a bit costly if your health care plan doesn’t cover it, it pays off in the long run.

Finally, it is safe even for women who breastfeed. However, have in mind that an IUD can’t protect you from STDs.

Side Effects

The biggest side effect of an IUD is the change in your period. For example, hormone-based devices can lessen the problems with cramps. Initially, you might experience some spotting between periods and your periods will become lighter. You might experience a complete loss of period after a while.

On the other hand, a copper device might initially make your periods heavier and worsen your problems with cramps. These side effects tend to go away within a few months.

If you contract a urinary infection while an IUD is in your uterus, it is of utmost importance to start treating it immediately to prevent any possible complications. An untreated infection in this case might cause sterility.

Who Shouldn’t Use an IUD?

IUDs are generally safe for healthy women. Doctors mostly recommend them to women who have only one partner and are not at risk of getting an STD. However, you shouldn’t use an IUD if you already have an STD. Likewise, if you’ve recently had a pelvic infection, you should skip IUDs.

Pregnant women shouldn’t use IUDs, either. It is also not recommended for women with uterus or cervix cancer to use this method of contraception. Women with unexplained vaginal bleeding should also avoid IUDs.

Women who are suffering from Wilson’s disease or are allergic to copper shouldn’t use the ParaGard brand. On the other hand, if you suffer from breast cancer or liver disease, you shouldn’t go with a hormone-based brand. Likewise, if you are at a higher risk of getting breast cancer, don’t use the hormone variety as progestin has been linked to the disease. However, there is no conclusive evidence as of yet and further research is needed.

What’s the Takeaway?

Modern-day IUDs are safe, effective, and last for a long time. Side effects, other than changes in the period intensity and frequency, are very rare. All five brands available on the US market have a failure rate of less than 1%, which puts them among the most effective and reliable contraceptive methods available to women.