how does an IUD work?

How Does an IUD Work? – Sept. 8, 2020

The IUD is not a new birth control option, but it has become more popular in recent years. According to Planned Parenthood statistics, IUD demand has climbed dramatically since 2016. A common question we get from our patients at One Community Health is: “how does an IUD work?” Read on to learn more about this popular contraception option. 

What Is an IUD?

IUD stands for intrauterine device. It is a long-term, very effective contraception option. The device itself is a small piece of plastic shaped like a “T” that is placed in the uterus. Depending on the specific device, IUDs last anywhere from 3-12 years, unless removed earlier.

How Does an IUD Work?

Like we mentioned above, there are different kinds of IUDs and each one works a little differently. Some are coated with copper and some are coated with hormones. Copper is toxic to sperm and when released into the uterus, acts as a spermicide, preventing fertilization. 

IUDs coated with the hormone progestin thicken the cervical mucus so the sperm can’t reach the egg. In some cases, it stops ovulation–the release of an egg during a woman’s monthly menstrual cycle. If no egg is released, pregnancy is not a risk. 

How Effective are IUDs?

IUDs are 99% effective at preventing pregnancy, making them one of the most effective forms of birth control available today. Part of why they are so effective is that they are virtually fool-proof, meaning you can’t forget to take it, or use it incorrectly, as is possible with pills and condoms. 

Benefits of IUDs

  • Convenient
  • 99% effective
  • Can be removed at any time if you wish to become pregnant
  • Hormonal IUDs can improve heavy periods
  • Non-hormonal option available for people who prefer (copper IUD)
  • Copper IUDs can serve as emergency contraception if placed within 5 days of unprotected sex 


The Downside 

Some people experience minor side effects, including: 

  • Irregular bleeding in the first few months
  • Heavier periods and more cramping (copper IUD)
  • Lighter/shorter periods, or no periods (some progestin IUDs)
  • PMS-like symptoms such as mood swings, headaches, acne, nausea, and breast tenderness (progestin IUD)


Rarely, there can be more serious side effects. The other drawback of IUDs is that they don’t protect against STDs.

Different Kinds of IUDs

There are four kinds of hormonal IUDs available. They all work the same, but last for different amounts of time. 

  • Mirenalasts up to 7 years
  • Kyleena—lasts up to 5 years
  • Liletta—lasts up to 7 years
  • Skyla—lasts up to 3 years 


There is only one kind of non-hormonal, or copper, IUD available in the U.S.—Paragard. This IUD lasts for up to 12 years. 

IUDs in Sacramento

If you have any more questions about how IUDs work or which option is right for you, be sure to talk to your One Community Health doctor. Learn more about our comprehensive women’s health services and how to become a patient by calling 916-443-3299.

Photo by Reproductive Health Supplies Coalition on Unsplash

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