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
  • Skyla

While IUDs are considered among the most effective birth control options, you should consider the differences between brands. 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


IUDs all have a number of similarities.

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 they're 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 healthcare provider. 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 sperm's ability to bind 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. Even as the released dosage 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 20 mcg 5 years
Liletta 19.5 mcg 4 years
Kyleena 17.5 mcg 5 years
Skyla 14 mcg 3 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:

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.


You should consider several factors when selecting an IUD. Have an open discussion with your healthcare provider about them before making a decision.

If you've had repeated episodes of pelvic inflammatory disease, liver disease, or irregular menstrual bleeding, an IUD may not be right for you. You and your healthcare provider can discuss your own risks versus 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.

Still, if you've had adverse effects from hormone exposure or have a history of breast, cervical, uterine, or ovarian cancer, you 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 you can keep the device in place ranges from a few years to a decade.

Length, financial considerations, and convenience may all be factors in 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 those who have a smaller uterus, which is the case when you're a teenager or perimenopausal. 


You should not use any IUD if you:

  • Ar pregnant or suspect you are
  • Have unexplained vaginal bleeding
  • Have an ongoing pelvic infection
  • Have known or suspected uterine or cervical cancer
  • Have 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 's 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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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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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. Nelson AL, Massoudi N. New developments in intrauterine device use: focus on the USOpen Access J Contracept. 2016;7:127-141. Published 2016 Sep 13. doi:10.2147/OAJC.S85755

  4. 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.

  5. 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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