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What are the side effects of IUDs?

Medically reviewed by Carmen Pope, BPharm. Last updated on Jan 17, 2023.

Official answer


In the U.S there are two types of intrauterine device (IUD) available:

  • Copper IUDs: ParaGard. These consist of a plastic device with copper wrapped around its stem. Copper interferes with sperm mobility and fertilization of an egg, and possibly also prevention of implantation of a fertilized egg
  • Hormonal IUDs: Mirena, Liletta, Skyla, and Kyleena These release the hormone progesterone which thickens cervical mucus and makes it difficult for sperm to enter the cervix. Progesterone also slows the growth of the lining of the uterus, making it inhospitable for a fertilized egg to implant.

The most common side effects of IUDs are pain on IUD insertion, cramps, bleeding, and unwanted pregnancy.

Pain on IUD insertion

Before inserting an IUD, a nurse or doctor will measure the depth of your uterus, a procedure known as uterine sounding. To insert the IUD a speculum is used to open your vagina to allow insertion of the IUD through the opening of your cervix into your uterus. Sometimes medicine is used to dilate the cervix or numb the area prior to IUD insertion.

Many women rate measuring the depth of the uterus as more painful than the actual IUD insertion. Reports of pain associated with IUD insertion vary widely, with some likening it to a bee sting whereas others describe it as pain of “cosmic proportions”.

A lot depends on your tolerability to pain and the position and the shape of your uterus. Doctors suggest taking a dose of ibuprofen (Advil) or naproxen (Aleve) an hour before the procedure and using a heating pad to help with any persistent cramps following insertion. You should also plan to have the rest of the day off after the procedure and go home and rest. Make sure you wear a panty liner or a sanitary napkin as there may be some spotting or bleeding after the procedure.


Cramping is common after IUD insertion because the cervix has to be opened to allow the IUD through. The degree of cramping varies greatly, ranging from low back pain to severe, debilitating, pelvic pain. Women who have previously given birth vaginally tend to experience less pain. For some women, the cramps will have subsided by the time they leave the doctors office, but for most the discomfort persists for several hours or days. Cramping usually subsides entirely within three to six months.

Cramping that persists is generally more common with the copper IUD. With the hormonal IUD, 30% reported increased cramping three months after insertion, whereas 25% reported an improvement in their cramping compared to before IUD placement.

Pain relieving medicines such as acetaminophen (Tylenol), ibuprofen (Advil), or naproxen (Aleve) can help with cramping but talk with your doctor about the best dosage to provide relief from your cramping, how long you should take them for, and check that they don’t interact with other medications you take. A heating pad or hot water bottle, exercise, or drinking rose hip tea can may also help.


Almost all women will experience some sort of bleeding after IUD insertion, and again this varies from occasional spotting (on and off blood spots or brown discharge) to heavy bleeding. Although the IUD can be inserted at any time during your menstrual cycle, during your period is the best time because your cervix sits lower and dilates, making it easier for the doctor to insert the IUD.

Make sure you wear a panty liner or a sanitary napkin to the appointment. Spotting generally persists for up to 90 days but occasional bleeding may occur for up to 6 months. Some women with hormonal IUDs may eventually have no periods while the IUD is in place, whereas irregular periods may persist with the copper IUD. If the bleeding is heavy and persistent see your doctor.

Unwanted pregnancy

IUDs are over 99% effective if inserted correctly and they remain in place.

A copper IUD is effective immediately and can even be used as emergency contraception if it is inserted within five days of unprotected sex.

Hormonal IUDs are only effective immediately if put in within the first seven days of your period, otherwise, you should use a condom if you have sex within seven days of insertion.

If you think you have become pregnant and have an IUD inserted, contact your doctor immediately to get it removed.

IUD warning signs

Talk to your doctor as soon as you can if you have the following symptoms:

  • A constant feeling of pressure in your uterus
  • Extreme dizziness or persistent lightheadedness
  • Large blood clots or very heavy, persistent bleeding
  • Pain during sex or in your lower cervix (may indicate that the IUD has displaced)
  • Pain during bowel movements
  • Persistent cramps or lower back pain like sciatica
  • Sharp pain below your belly button or severe pain in your lower stomach or side
  • Severe migraine headaches or mood changes
  • Signs of an allergic reaction (difficulty breathing, facial or throat swelling, hives or another type of rash)
  • Sudden numbness or weakness, especially on one side of your body
  • Unexplained abdominal bloating or swelling
  • Unexplained weight gain
  • Vaginal discharge that is foul-smelling or unusual
  • Yellowing of the skin or eyes
  • Your period flip-flops between light and heavy for several months
  • You think you might be pregnant.

Sometimes an IUD falls out by itself, most commonly within the first three months. It’s good to check that you can feel the strings of the IUD (or ask your partner to check that they are still there), although sometimes they coil up and sit just behind the cervix and can’t be felt. Make an appointment to get a new IUD inserted if it falls out or you can feel the hard plastic bottom of the IUD coming out through your cervix.

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