The different types of IUDs and how to decide which is best for you

• There are five types of IUDs, all of which are more than 99% effective at preventing pregnancy.
• IUDs can be divided into one of two categories: hormonal and non-hormonal.
• Which IUD is best for you depends on how long you want it for and your hormonal sensitivity.

Intrauterine devices, or IUDs, are some of the most effective forms of contraception. There are several types of IUDs available and they work in different ways. Here's a breakdown of the types of IUDs and how to choose the best one for you.

How do IUDs work?

IUDs are a type of long-acting reversible contraception (LARC), meaning they last for several years and do not affect your fertility once removed. They are small, T-shaped devices that are placed in the uterus by a qualified provider in a doctor's office, says Erica Chang, MD, an OB-GYN with Keck Medicine of USC in Glendale, California.

IUDs are meant to prevent pregnancy and do not protect against sexually transmitted infections (STIs), Chang says. They are more than 99% effective at preventing pregnancy. Fewer than 1 out of 100 people who get an IUD will get pregnant each year.

There are two main categories of IUDs:

• A hormonal IUD contains a synthetic form of the hormone progesterone called levonorgestrel.
• A non-hormonal IUD is made of copper and does not contain any hormones.

Hormonal IUDs

There are four different types of hormonal IUDs. They differ in the duration of their effectiveness, the total amount of hormone per device, and the size of the IUD, says Richard Beyerlein, MD, an OBGYN with his own practice in Oregon.

However, all contain the same hormone - a progestin called levonorgestrel, says Chang. Levonorgestrel works to prevent pregnancy by:

• Thickening cervical mucus to prevent sperm from entering the uterus
• Preventing ovulation when an egg is released
• Thinning the lining of the uterus to prevent implantation

Here's how the four different types of hormonal IUDs stack up:

The side effects of hormonal IUDs vary depending on the type, but in general, the most common ones include:

• Shorter, lighter, or nonexistent periods
• Acne
• Changes in weight
• Nausea
• Mood changes
• Irregular bleeding

Severe complications, like perforation, are rare and only seen in cases where IUDs are placed improperly or in the case of undiagnosed infection, Chang says. However, even an IUD that is malpositioned or causes a small perforation can usually be removed with minor surgery and minimal risk for any long-term problems.

Non-hormonal IUD

Non-hormonal IUDs do not contain levonorgestrel and are instead made of copper, which is thought to prevent pregnancy by interfering with sperm movement and preventing implantation, Chang says. Paragard is the only non-hormonal IUD option in the US.

Paragard lasts up to 12 years and is 99.9% effective at preventing pregnancy. Because it does not contain hormones, Paragard does not stop your period.

Side effects of Paragard include:

• Spotting between periods or irregular periods
• Pain during insertion with continued cramps or aches for a few days after
• Worsening cramps and bleeding during your period, especially in the first three to six months

You should not use a copper IUD if you are allergic to copper or have Wilson's disease, which causes your body to hold too much copper, Beyerlein says. Too much copper in your body can cause kidney and liver problems.

Which type of IUD is right for me?

Deciding which IUD is best for you will depend on many individual factors, your health history, and how long you would like your birth control to last.

If you have heavy periods and would like to shorten or stop them, a hormonal IUD could help with that, Chang says. On the other hand, some people are more sensitive to hormonal birth control and would like to avoid progestin, in which case the copper IUD may be a better fit.

Here are the overall differences between the five IUD options:

The cost of an IUD can range widely depending on your insurance coverage. Talk with your provider about your options and the best choice for you.

A note on IUD complications

No matter which IUD you choose, you should be aware of three rare yet serious complications:

• Expulsion is when your IUD falls out. This occurs in about 0.5% to 8% of cases with higher rates of expulsion when an IUD is placed immediately after delivery.
• Perforation is when the IUD pokes through the wall of the cervix or uterus. Perforation happens in about 1 in 1,000 insertions.
• Ectopic pregnancy is when an egg gets fertilized but implants in the tube instead of the uterus. While it is rare to become pregnant with an IUD in place, 4% to 7% may be ectopic pregnancies.

Insider's takeaway

An IUD is a type of long-acting reversible contraception that is 99% effective at preventing pregnancy. Some IUDs contain hormones and some do not. Each type lasts for a different amount of time and may result in different side effects.

To determine the best IUD for you, talk with your doctor about your health history, how sensitive you are to hormonal contraception, and how long you'd like your birth control to last.

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