How to Choose the Right IUD

Evaluating Size, Duration, and Method of Action

Intrauterine devices (IUDs) are T-shaped devices that can be inserted into your uterus to prevent pregnancy. There are five FDA-approved brands of IUDs available in the United States: Kyleena, Liletta, Mirena, ParaGard, and Skyla. While IUDs as a birth control option are considered among the most effective, there are differences among your options, which need to be considered. Knowing more about them can help you decide whether an IUD is right for you and, if so, which one.

how to choose an IUD
Illustration by Brianna Gilmartin, Verywell


Overall, there are a number of similarities between all of the IUDs you can choose from. From the broadest perspective, all of the IUDs approved by the U.S. Food and Drug Administration (FDA) are considered to be highly effective methods of birth control. They can be used on their own and are reversible, meaning that you can become pregnant once you stopping using the IUD.

All IUDs must be placed into your uterus and removed by a doctor. Depending on the brand, they can be kept in place for anywhere from three to 10 years.

IUDs generally have a low risk of side effects and adverse events. There is a risk of expulsion (the IUD falling out). If this occurs, you can get pregnant until you begin to use another method of birth control or have your IUD replaced. There is also a slight risk of pelvic infection or a uterine tear, although these complications are uncommon.

Medical evidence indicates that due to the location of the IUD, there is a slightly increased risk of an ectopic (tubal) pregnancy. Ectopic pregnancies are non-viable and potentially life-threatening if the implanted egg causes the rupture of the fallopian tube.


The main distinction among the IUDs is that all but one release the hormone levonorgestrel (a progestin) to prevent pregnancy. In contrast, ParaGard, which is hormone-free, works because it is made of copper.

Levonorgestrel IUDs

Marketed under the brand names Mirena, Liletta, Skyla, and Kyleena, these IUDs are composed of a polydimethylsiloxane sleeve that contains levonorgestrel, a progestin hormone, on the stem.

Levonorgestrel prevents pregnancy by thickening the cervical mucus, thinning the uterine wall, and impairing the binding of sperm to the egg. Not only is fertilization unlikely, the odds of implantation are low even if fertilization occurs.

The hormone doses differ for each of the levonorgestrel IUDs. They each initially release a higher dose of the hormone, which decreases over time. As the dose of hormone released declines, the device remains effective in preventing pregnancy throughout the duration of recommended use.

Each brand is recommended for a specified time period, ranging from three to five years.

  • Mirena initially releases 20 mcg of levonorgestrel per day and is FDA-approved for up to five years.
  • Liletta initially releases 19.5 mcg per day of levonorgestrel and is approved for four years of use. 
  • Skyla initially releases 14 mcg of levonorgestrel per day and can be used for up to three years. 
  • Kyleena initially releases 17.5 mcg of levonorgestrel per day. It can remain in place for five years.

Because these four IUDs contain progestin, you may experience a decrease in your menstrual flow. For instance, you may spot for the first few months and then have lighter and shorter periods. Your period may also stop altogether, which is considered safe.

Other side effects may include headaches, nausea, breast tenderness, depression, decreased libido, hair loss, and ovarian cysts.

Copper IUD (ParaGard)

ParaGard is the only hormone-free IUD approved by the FDA. It is composed of polyethylene wrapped with copper wire and has an entirely different mechanism of action.

ParaGard prevents pregnancy by triggering an inflammatory response to the copper which damages the egg, impairs the movement and viability of sperm, and diminishes the ability of an egg to implant even if it is fertilized.

Of all the IUDs, the ParaGard can be used for the longest duration, which is up to 10 years.

Because the copper IUD is hormone-free, it should not alter the timing of your menstrual cycle. However, it may cause heavy periods with more cramping or back pain than usual, especially in the first several menstrual cycles after its placement.


There are several factors that you must consider when selecting an IUD. Have an open discussion with your doctor about them before making a decision about an IUD.

If you have a history of repeated episodes of pelvic inflammatory disease, liver disease, or irregular menstrual bleeding, an IUD may not be right for you. You and your doctor can discuss your own risk vs. benefits of having an IUD.

Hormone Exposure

If you cannot or choose not to be exposed to hormones, the ParaGard IUD may be the best choice for you. The hormone in Mirena, Skyla, Liletta, and Kyleena is only released into the uterus, so it does not have the same kind of broad effect as the hormones found in birth control pills. But women who have adverse effects from hormone exposure or who have a history of breast, cervical, uterine, or ovarian cancer may choose to stay away from hormone use.

Remember that the hormone doses released by each device differ, which may be a particularly important consideration if you experience side effects and menstrual changes.

Duration of Effectiveness

The length of time during which you can keep the device in place ranges from a few years to a decade. Because of this, financial and convenience considerations, among others, may play into your choice.

Size of the IUD

Skyla and Kyleena are a little bit smaller than Mirena, Liletta, and ParaGard. Skyla and Kyleena's smaller size may be better tolerated by women who have a smaller uterus, such as young teens and perimenopausal women. 


Absolute contraindications for the use of any IUD include:

  • Pregnancy or suspicion of pregnancy
  • Unexplained vaginal bleeding
  • Ongoing pelvic infection
  • Known or suspected uterine or cervical cancer
  • Any uterine abnormality, including fibroids, that interferes with the placement of the IUD

A Word From Verywell

No matter which IUD you choose, you can have the peace of mind that all five are considered safe and among the most effective forms of birth control methods. In fact, they are as effective as permanent methods, like vasectomies and tubal ligation. Additionally, they do not affect your chance of getting pregnant after removal. 

It is important to keep in mind that IUDs do not protect you from sexually transmitted infections (STDs) and that you need to use a barrier method of protection if you are sexually active with a partner who could be infected with an STD.

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Article Sources
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  2. Nelson AL, Massoudi N. New developments in intrauterine device use: focus on the US. Open Access J Contracept. 2016;7:127–141. Published 2016 Sep 13. doi:10.2147/OAJC.S85755

  3. Grandi G, Farulla A, Sileo FG, Facchinetti F. Levonorgestrel-releasing intra-uterine systems as female contraceptives. Expert Opin Pharmacother. 2018 May;19(7):677-686. doi:10.1080/14656566.2018.1462337.

  4. Sanders JN, Adkins DE, Kaur S, Storck K, Gawron LM, Turok DK. Bleeding, cramping, and satisfaction among new copper IUD users: A prospective study. PLoS One. 2018;13(11):e0199724. Published 2018 Nov 7. doi:10.1371/journal.pone.0199724

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