Expert advice on the use of the IUD (Mirena or copper)

There are many questions and uncertainties about the appropriate use of intrauterine devices (IUDs). IUDs are among the most commonly used reversible contraceptive methods worldwide because of their high effectiveness, ease of use, and long duration of action. Before choosing an IUD, patients should understand the different types available, the insertion and removal processes, effects on menstrual bleeding and fertility, potential side effects and complications, and the clinical situations in which one type may be preferred over another.

This article provides evidence-based, clinician-oriented guidance about the two main types of IUDs—the copper IUD and the levonorgestrel-releasing IUD (commonly known by brand names such as Mirena). Information and recommendations are presented in a medical, non-explicit manner suitable for patient counseling and clinician reference. Sources include practice guidance and patient information from the American College of Obstetricians and Gynecologists (ACOG), the National Institutes of Health (NIH/MedlinePlus), the Mayo Clinic and the Cleveland Clinic.

References are listed at the end of the article.

Overview: What is an IUD?

An intrauterine device (IUD) is a small, usually T-shaped device that a clinician places inside the uterine cavity to prevent pregnancy. IUDs are long-acting reversible contraceptives (LARCs). They are safe, highly effective, and reversible—fertility typically returns quickly after removal.

There are two broad categories of IUDs:

Hormonal IUDs (levonorgestrel-releasing), e.g., Mirena, which release a progestin hormone locally within the uterus.
Copper IUDs, e.g., ParaGard, which are non-hormonal and exert contraceptive effects through copper ions and a local inflammatory response.

(See authoritative summaries: ACOG; MedlinePlus; Mayo Clinic; Cleveland Clinic.)

How the two types differ: mechanism, efficacy, and typical effects

Mechanism of action

Copper IUD:
Acts primarily as a foreign body within the uterine cavity and releases copper ions.
Copper has toxic effects on sperm and impairs sperm motility and viability, preventing fertilization.
The local uterine inflammatory reaction also reduces the likelihood of implantation.
Levonorgestrel (hormonal) IUD:
Releases a progestin (levonorgestrel) locally, which thickens cervical mucus to inhibit sperm passage, thins the endometrial lining, and may suppress ovulation in some users.
The dominant actions are within the uterus and cervix; systemic hormone levels are lower than with many systemic hormonal methods.

(A detailed review is available from ACOG and NIH/MedlinePlus.)

Effectiveness

Both types are highly effective contraceptives with typical-use failure rates well below those of pills, patches, or condoms.

Levonorgestrel IUDs generally have failure rates under 1% per year (very low).
Copper IUDs also have a typical-use failure rate near or below 1% per year, though some studies indicate slightly higher pregnancy rates for copper IUDs than for levonorgestrel IUDs over similar durations.

IUDs are considered among the most effective reversible contraceptives. (See ACOG practice statements; Mayo Clinic patient information.)

Effects on menstrual bleeding and cramping

Copper IUD:
Often associated with heavier menstrual bleeding and increased menstrual cramping (dysmenorrhea), especially during the first several months after insertion. In some users these effects persist.
Levonorgestrel IUD (Mirena-type):
Typically reduces menstrual blood loss over time. Many users experience lighter periods; amenorrhea (absence of menses) can occur in some individuals after several months of use.
Irregular spotting or breakthrough bleeding is common in the first 3–6 months after placement, then typically stabilizes to lighter or absent menses.

(Mayo Clinic and Cleveland Clinic provide patient-focused descriptions of these bleeding patterns.)

Who is a good candidate for each IUD?

Choice of IUD should be individualized based on medical history, preferences regarding hormonal exposure, bleeding patterns, and reproductive goals.

Consider levonorgestrel IUD for:
Individuals who desire reliable contraception and prefer decreased menstrual bleeding (e.g., heavy menstrual bleeding or anemia).
Those who are comfortable with intrauterine hormonal delivery and can tolerate possible hormonal side effects (usually mild and localized).
Consider copper IUD for:
Individuals who prefer a non-hormonal method.
Those who do not want the potential systemic progestin effects or who wish to avoid hormones for other reasons.

Absolute contraindications for either IUD include current pregnancy and active pelvic infection. Specific medical conditions (e.g., certain uterine anomalies that distort the cavity, untreated cervical or uterine cancer) may preclude IUD placement. The copper IUD is generally avoided in patients with Wilson disease or a known copper allergy. Clinical eligibility should follow established professional guidance and a structured medical screening before insertion. (See ACOG and MedlinePlus.)

Counseling and informed consent

Before an IUD is placed, clinicians should:

Review alternative contraceptive methods, the relative efficacy of each, and the reversible nature of IUDs.
Discuss the likely effects on menstrual bleeding and any other expected side effects.
Explain insertion and removal procedures, follow-up recommendations, and how to check IUD strings.
Screen for sexually transmitted infections (STIs) based on risk and local protocols. Active, untreated chlamydia or gonorrhea should be treated prior to IUD insertion. If STI testing is pending, insertion may still be appropriate with appropriate counseling and follow-up depending on clinical judgment and local guidelines.
Provide clear instructions for when to seek urgent medical care (e.g., severe abdominal pain, fever, heavy bleeding, pregnancy symptoms, or if the strings are missing after an initial period).

ACOG and other professional organizations recommend offering IUDs to most women and adolescents who desire long-acting contraception, with individualized counseling to support informed decision-making.

The insertion procedure: what to expect

Timing and prerequisites

IUDs can be inserted at any time during the menstrual cycle if pregnancy is reasonably excluded.
Many clinicians perform insertion during menstruation because the cervix may be slightly more open and a negative pregnancy test is more reliable.
Immediate postpartum insertion (within 10 minutes to several weeks after delivery) and immediate post-abortal insertion are options in many clinical settings. Immediate postpartum insertion may have a higher risk of expulsion but avoids loss to follow-up and provides effective contraception when desired.
Before insertion, clinicians typically perform a pelvic examination, test for pregnancy when indicated, and screen for STIs according to local protocols.

(See ACOG and Cleveland Clinic guidance on timing.)

The procedure

Performed in an outpatient clinic setting.
The clinician uses a sterile speculum, cleans the cervix, and measures uterine depth and orientation (uterine sounding) to select correct placement depth.
The IUD is delivered through the cervical canal into the uterine cavity using a dedicated inserter; the device unfolds into a T-shape.
Threads (strings) that extend through the cervical canal into the proximal vagina are trimmed to a length that facilitates clinician checks and allows the patient to feel the strings.
The procedure requires a few minutes; many patients experience cramping and discomfort during insertion and for a short period after. Analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) prior to the procedure can reduce immediate pain for some patients.

Cervical anesthesia or other pain management strategies may be used in select cases for patient comfort. The risk of major immediate complications is low in experienced hands. (See Mayo Clinic; Cleveland Clinic.)

Expected side effects and early reactions

Immediately after insertion: transient cramping, light bleeding, and dizziness are common.
First 3–6 months: irregular bleeding and spotting are common with levonorgestrel IUDs; heavier bleeding may occur with copper IUDs, particularly early on.
Systemic hormonal side effects: levonorgestrel released by the IUD is primarily local, but some users report systemic effects such as mood changes, acne, breast tenderness, headaches, or changes in libido. These are usually mild and often resolve.
Long-term: levonorgestrel IUDs frequently reduce menstrual blood loss and can be used therapeutically for heavy menses; copper IUDs may be associated with heavier cycles and increased cramping.

If side effects are troublesome and persistent, removal is an option; alternative contraception may be discussed.

Follow-up and self-checking

Routine follow-up visit is commonly scheduled 4–12 weeks after insertion to assess placement and address early issues. Some providers perform no routine visit if the patient is asymptomatic and understands how to check strings.
Patients should be taught how to feel for the IUD strings in the vagina. If the strings are not felt or if the patient feels only the hard part of the IUD (rare), clinical evaluation with a pelvic exam and, if necessary, ultrasound is recommended.
If the strings cannot be found, pregnancy should be excluded and imaging such as transvaginal ultrasound can confirm intrauterine placement or detect expulsion or perforation.

Complications: what are the risks and how common are they?

IUDs are generally safe, but potential complications should be discussed:

Expulsion:
Partial or complete expulsion of the IUD occurs in a minority of users, most commonly within the first months after insertion. Estimates vary by population but reported rates are roughly 2–10% overall and may be higher in the immediate postpartum setting or in younger/nulliparous users.
Perforation:
Uterine perforation during insertion is rare (approximately 1 per 1,000 insertions) but is a serious event. It is more likely to occur when the uterus is softer (e.g., immediately postpartum) or if insertion technique is difficult. If perforation is suspected, imaging is required and surgical consultation may be needed.
Infection:
The risk of pelvic inflammatory disease (PID) is low after IUD insertion; however, if an undiagnosed STI is present at the time of insertion, the risk of ascending infection increases. Most excess PID risk is confined to the first 20 days following insertion if an infection is introduced at the time of placement.
Pregnancy with an IUD in place:
Pregnancy is uncommon with a properly placed IUD, but when it occurs it may carry an increased relative risk of ectopic pregnancy compared with pregnancies in the general population. However, because IUDs greatly reduce overall pregnancy risk, the absolute risk of ectopic pregnancy is lower than in women using no contraception.
If pregnancy occurs with an IUD in place, prompt evaluation is required. If the pregnancy is intrauterine and the strings are visible, removal of the IUD is generally recommended to reduce the risk of miscarriage and infection; removal should be performed carefully with counseling about potential risks.
Other complications:
Pain, bleeding requiring clinical attention, and device malposition may occur and require assessment and management.

(For risk estimates and further details, see ACOG and MedlinePlus.)

Removal and return to fertility

Removal is a straightforward outpatient procedure: the clinician gently pulls the strings and the IUD is withdrawn through the cervix. This typically causes a brief cramp and light bleeding.
Fertility generally returns rapidly after removal. Menstrual cycles typically resume according to the individual’s baseline pattern, and pregnancy can occur soon after removal if contraception is not used. This makes IUDs an attractive option for those who desire eventual pregnancy without delay.
If removal is indicated due to desire for pregnancy or unsatisfactory side effects, it can generally be performed at any time.

(Refer to Mayo Clinic and Cleveland Clinic for typical timelines.)

Duration of use and replacement

Levonorgestrel IUDs (brands and labeled durations vary):
Mirena has been approved for use up to 5–8 years for contraception depending on local labeling and product generation; other levonorgestrel IUDs have different labeled durations (e.g., Skyla, Kyleena). Confirm current product-specific recommendations with up-to-date prescribing information and local regulatory approvals.
Copper IUDs:
Some copper IUDs are labeled for up to 10–12 years of use depending on specific product and manufacturer.
When the effective labeled duration is reached or if the patient desires removal or replacement earlier, the IUD should be removed or changed. A new IUD may be placed immediately after removal if ongoing contraception is desired.

Clinicians should counsel patients regarding the specific duration of the device provided and document the insertion date and recommended removal date.

Special clinical situations

Postpartum and breastfeeding individuals

IUDs can be placed postpartum. Immediate postpartum insertion (within minutes after placental delivery) is an accepted option; however, immediate insertion may be associated with higher expulsion rates. Delayed insertion at 6 weeks postpartum is also common.
Levonorgestrel IUDs are considered compatible with breastfeeding. Progestin-only methods generally do not adversely affect milk production.

(See ACOG guidance on postpartum contraception.)

Adolescents and nulliparous patients

IUDs are safe and highly effective choices for adolescents and those who have never had a pregnancy. Professional organizations encourage offering LARC methods to adolescents who desire highly effective contraception, with appropriate counseling about potential side effects and expectations.

STI risk and condom use

IUDs do not protect against sexually transmitted infections. Condom use should be discussed for STI prevention, particularly in individuals at risk for STIs.

When to seek medical attention

Seek prompt clinical evaluation if any of the following occur:

Severe or persistent abdominal pain, fever, or chills.
Heavy vaginal bleeding (soaking through a pad every hour for several hours).
Foul-smelling vaginal discharge (possible infection).
Symptoms of pregnancy (missed period, nausea, breast tenderness) while the IUD is in place.
Loss of strings or inability to feel strings when previously present.
Partner feeling something unusual (e.g., strings) or persistent discomfort during intercourse.

Early assessment helps identify complications such as expulsion, infection, perforation, or pregnancy.

Comparing risks and benefits: clinical perspective

When counseling patients, consider the following clinical points:

Effectiveness: Both IUD types provide excellent contraceptive efficacy. Levonorgestrel IUDs may have slightly lower failure rates than copper IUDs in some studies.
Bleeding patterns: For patients with heavy menstrual bleeding or anemia, levonorgestrel IUDs are often therapeutic and may reduce bleeding and dysmenorrhea. Copper IUDs may worsen menstrual bleeding and cramps in some users.
Hormonal exposure: Copper IUDs are a non-hormonal option suitable for those who prefer to avoid systemic hormones. Levonorgestrel IUDs provide mainly local progestin effects with low systemic exposure.
Side effects and contraindications: Discuss device-specific contraindications and potential side effects. Screen and treat STIs prior to insertion when appropriate.
Reversibility: Both methods are reversible with rapid return to fertility after removal.

Shared decision-making, taking into account the patient’s medical history, preferences, and reproductive goals, is essential.

Practical tips for clinicians in counseling and insertion

Use clear, patient-centered language to explain differences between the devices, including bleeding expectations and how to check strings.
Review the patient’s medical history and perform appropriate testing (pregnancy test if indicated, STI screening per risk).
Offer analgesia options and counseling about procedural discomfort.
Provide written instructions about post-insertion care and when to seek evaluation.
Document the device type, lot number, insertion date, and recommended removal date in the medical record.
Ensure access to follow-up care for removal, replacement, or management of complications.

Summary

IUDs—both copper and levonorgestrel-containing devices—are highly effective, long-acting, reversible contraceptives suitable for a wide range of patients. The levonorgestrel IUD (e.g., Mirena) tends to reduce menstrual bleeding and may cause amenorrhea in some users, making it a valuable option for those with heavy menses. The copper IUD is a hormone-free alternative but may increase menstrual bleeding and cramping in some individuals. Both devices have low rates of serious complications when properly screened and inserted by trained clinicians. Thorough counseling, appropriate screening for infection, and accessible follow-up care are essential components of safe IUD use.

For personalized medical advice, individuals should consult their clinician to discuss medical eligibility, device options, insertion logistics, and any questions about risks, benefits, and alternatives.

References and further reading

American College of Obstetricians and Gynecologists (ACOG). Intrauterine Device (IUD). Patient FAQ. https://www.acog.org/womens-health/faqs/intrauterine-device-iud
MedlinePlus (U.S. National Library of Medicine / NIH). Intrauterine device. https://medlineplus.gov/intrauterinedevice.html
Mayo Clinic. IUD (Intrauterine device). Overview, insertion, side effects. https://www.mayoclinic.org/tests-procedures/iud/about/pac-20384719
Cleveland Clinic. Intrauterine Device (IUD): Types, insertion, risks. https://my.clevelandclinic.org/health/treatments/9154-intrauterine-device-iud

(Clinicians should consult current device-specific labeling and local clinical guidelines for up-to-date recommendations on durations of use and special circumstances.)