Intrauterine Device (IUD)


What is an intrauterine device?

An intrauterine device (called an IUD for short) is a small, T-shaped device with a string attached to the end (the string hangs outside the cervix so that you can check every so often to make sure the IUD is still in place). The IUD is placed inside the uterus to prevent pregnancy. This placement can be done during an office visit. Once in place, the IUD stays in your uterus until your doctor removes it.

How does it work?

The IUD prevents sperm from joining with an egg. It does this by making the sperm unable to go into the egg and by changing the lining of the uterus. There are 2 types of IUDs: a copper IUD and a hormonal IUD. The copper IUD releases copper particles to prevent pregnancy, while the hormonal IUD releases the hormone progestin to prevent pregnancy.

What are the advantages of an IUD?

The IUD has many advantages:

  • It's very effective in preventing pregnancy (and once inserted, you are protected from pregnancy until the IUD is removed).
  • It can prevent pregnancy for up to 5 to 10 years
  • It's inexpensive.
  • It's convenient (there is nothing to remember to do, such as taking the birth control pill every day).
  • An IUD can be removed by your doctor at any time.
  • It starts working right away.
  • There's a low risk of side effects.
  • Mothers who use an IUD can breastfeed safely.
  • Neither you nor your partner can feel it.

What are the disadvantages?

You may have cramps and a backache for the first few hours after an IUD is inserted into your uterus. Some women have bleeding and pain for a couple of weeks after the IUD is inserted. You may experience heavier periods if you are using the copper IUD. Rarely, the uterus can be injured when the IUD is put inside.

An older kind of IUD (which is no longer available) had serious side effects, including pelvic infections and infertility (problems getting pregnant after removal). These problems are very rare with the new IUDs.

The IUD does not protect you from any sexually transmitted infections (STIs). The more people you have sex with, the greater your chance of getting an STI. The IUD alone is best for women who have only one long-term sex partner. In addition, you shouldn't use the IUD if you're pregnant, if you have abnormal bleeding or if you have cancer of the cervix or uterus. You should not use the copper IUD if you are allergic to copper.

How long is an IUD effective?

It depends on the kind your doctor prescribed to you. The copper IUD can remain in your body as long as 12 years. The hormonal IUD needs to be replaced every 5 years. Your doctor can remove either of these at any time if you decide to get pregnant or if you no longer want to use it.

How do I care for my IUD?

After your IUD is put in place, you may swim, exercise, use tampons and have sex as soon as you want to. At the time of each menstrual period, you should check for the IUD string inside the vagina by inserting a clean finger in your vagina. Call your doctor if you can't feel the string or if you feel the IUD itself. Either of these could mean that the IUD is not in the right place and needs to be repositioned. Call your doctor if you miss your period or if you notice any unusual fluid or odor coming from your vagina. Continue to have regular check-ups every year.


Appropriate Use of the Intrauterine Device by Timothy P. Canavan, M.D. (American Family Physician December 01, 1998,

Written by editorial staff

Reviewed/Updated: 07/10
Created: 09/00