This article refers to the levonorgestrel intrauterine device (LNG-IUD), which used to be called the intrauterine system (IUS). For information on the copper-containing (non-hormonal) intrauterine device see the separate Intrauterine contraceptive device article. For information on insertion techniques see the separate Intrauterine contraceptives (IUCD and IUS) - management article.

What is a levonorgestrel intrauterine device?

Description and licensed indications

The LNG-IUD is an intrauterine contraceptive which releases levonorgestrel (LNG). Mirena® was the first LNG-IUD and has been available in the UK since 1995, but there are now four other brands available.

All LNG-IUDs have a plastic T-shaped frame with a reservoir LNG, which is released at a different rate depending on the brand.

The table below shows the different doses and licenses for the LNG-IUDs available in the UK. Depending on the brand, it may be licensed for menorrhagia (heavy periods) and as part of HRT, as well as for contraception.

¹

Other brands are available in other countries.

Real-life indications and use

The 2023 FSRH guidance on intrauterine devices ² said that all 52mg devices could be used for five years as the progestogen component of HRT and for six years for contraception. Published in summer 2023, this predated the lengthening of the Mirena® licence to eight years in January 2024. ³

In May 2024, the FSRH published a statement recommending the use of all 52 mg LNG-IUDs for 8 years use (contraception only) and 5 years use as part of HRT. A woman who is using her LNG-IUD for both of these purposes must have it changed at 5 years. ⁴

This means that many LNG-IUDs will be used outside of their product licence in the UK, supported by FSRH guidance. The different uses of the LNG-IUD are discussed in more detail later in this leaflet.

Cost-effectiveness

• The LNG-IUD (and other methods of long-acting reversible contraception (LARC)) is more cost-effective than the combined oral contraceptive (COC) pill, even at one year of use.⁵ It is also more cost-effective than injectable contraceptives.

• Cost per year is currently cheapest for Levosert®, and most expensive for Jaydess®.

• The National Institute for Health and Care Excellence (NICE) advises that increasing the uptake of LARC methods will reduce the numbers of unintended pregnancies.⁵ It is important that women should be advised of LARC methods when seeking contraception. Over the past ten years, rates of LARC use have been rising, with data showing 55% of women attending sexual and reproductive services in England now choose LARCs. This is a significant increase from the 37% who used them in 2014-15, although the increase slowed between 2020 and 2022, probably due to reduced availability during the COVID-19 pandemic. 16% use a LNG-IUD. ⁶

Mode of action²

• The primary contraceptive effect is mediated by its suppressant effect on the endometrium, which prevents implantation: within one month of insertion, high intrauterine LNG levels cause endometrial atrophy and changes in the stroma.

• There is an increase in endometrial phagocytic cells which also prevents implantation.

• There is some decreased sperm penetration of cervical mucus and impaired sperm migration.

• There is little effect on the hypothalamic-pituitary-ovarian axis: oestrogen levels are not reduced and most women continue to ovulate.

• Amenorrhea with the LNG-IUD does not necessarily indicate anovulation. Incidence of anovulation has been shown to be lower with the 13.5 mg device than the 52 mg device.

Effectiveness

Comparative tables of contraceptive efficacy suggest that the LNG-IUD is the most effective type of contraception other than the progestogen implant and male sterilisation, with 0.2% of women experiencing an unintended pregnancy within the first year of use. ⁷This is lower than the pregnancy rate following female sterilisation.

Indications

Contraceptive use

• The LNG-IUD is a suitable option for most women who need contraception, with few conditions where risks of use outweigh benefits (see 'Contra-indications and cautions', below).

• It can be appropriate for many women, including those who traditionally offer contraceptive challenge, such as women with obesity, diabetes, epilepsy or migraine and women with other contra-indications to oestrogen (see the separate Contraception and special groups article).^{5 2}

• The LNG-IUD can be used at any age, and may be used in nulliparous women.

• The LNG-IUD should not be used as emergency contraception (see the separate Emergency contraception article).

Advantages as a contraceptive method

These include:

• Rapid return of fertility post-removal.

• Reduced menstrual loss and dysmenorrhoea.

• Convenience (long-lasting method that is independent of intercourse).

• Lack of significant interactions with hepatic enzyme-inducing drugs. ⁸

• Useful in the perimenopausal years where both contraception and HRT may be required together.

Disadvantages as a contraceptive method

These include:

• Initial menstrual irregularities.

• Other side-effects (see below).

• Women may dislike the idea of the fitting procedure.

• Fitting an LNG-IUD is sometimes technically more difficult (in view of its larger diameter) than fitting a copper intrauterine device, particularly in nulliparous or perimenopausal women. However, Kyleena® and Jaydess® may be fitted more easily, as the frame is smaller and narrower.

Non-contraceptive uses

Menorrhagia

The Mirena® LNG-IUD is the first-line pharmaceutical treatment for HMB (where there is no identified pathology or <3 cm fibroids or adenomyosis) and can reduce menstrual losses by over 90%.⁹

Comparisons to alternative methods of managing this can be found in the separate Menorrhagia article. It is important to note that effectiveness of pharmacological treatments for HMB may be limited in women with fibroids that are substantially greater than 3 cm in diameter.⁹

Hormone replacement therapy (HRT)

• The Mirena® LNG-IUD is licensed for the prevention of endometrial hyperplasia during oestrogen replacement therapy for up to four years, but the FSRH advises that all 52mg LNG-IUDs can be used for this purpose for up to five years. ²

• It provides a means of delivering endometrial protection with minimum systemic absorption of progestogen.

Endometrial hyperplasia

The Royal College of Obstetricians and Gynaecologists (RCOG) guideline recommends the LNG-IUD as the first-line of treatment for endometrial hyperplasia without atypia, as it is more effective than oral progestogens and has a more favourable profile with regard to adverse effects. This use is unlicensed.^{10 11} The guideline also advises use in hyperplasia with atypia for women who are not suitable for hysterectomy or who wish to preserve fertility.

Endometriosis

The LNG-IUD is recommended by NICE as an option for the primary care management of endometriosis. ¹²

Future uses

Other potential uses of the LNG-IUD include its role in the treatment of

• Endometrial protection for women on tamoxifen - the LNG-IUD provides endometrial protection from tamoxifen-induced changes, reducing the risk of endometrial hyperplasia and benign polyps . A Cochrane review concluded that there was not yet evidence that it reduces the risk of endometrial cancer in this situation, and although there is no evidence that it affects risk of breast cancer recurrence or death, further trials are needed.¹³

• Endometrial carcinoma - the LNG-IUD may have a role in early-stage carcinoma and in patients unfit for surgery; there is ongoing research into whether biomarkers can identify the women in which this will be successful.¹⁴

Contra-indications and cautions¹⁵

Absolute contra-indications - UK Medical Eligibility Criteria (UKMEC) category 4 (use represents an unacceptable health risk)

• Infection: current pelvic inflammatory disease (PID) or purulent cervicitis, current symptomatic chlamydia or gonorrhoea, septic abortion or postpartum endometritis, pelvic tuberculosis.

• Current pregnancy.

• Some cancers: cervical cancer, endometrial cancer, malignant trophoblastic disease, current breast cancer.

• Undiagnosed irregular vaginal bleeding/suspicion of genital malignancy.

Relative contra-indications - UKMEC category 3 (risks usually outweigh benefits)

• 48 hours to four weeks postpartum (Insertion within the first 48 hours is considered safe).

• Complicated organ transplant.

• Long QT syndrome.

• Gestational trophoblastic disease with decreasing hCG levels.

• Past history of breast cancer.

• Uterine fibroids with distortion of the uterine cavity and other conditions causing distortion of the uterine cavity.

• Asymptomatic chlamydial infection.

• HIV with low CD4 count (contraindication only for insertion, not for continued use of a device which is in situ when the HIV is diagnosed

• Hepatocellular adenoma or carcinoma.

• Severe cirrhosis.

For women with cardiac disease, FSRH guidance suggests the decision to use intrauterine contraception should involve a cardiologist.² If there is a high risk of vasovagal reaction, it should be fitted in a hospital setting (eg, women with single ventricle circulation, Eisenmenger physiology, tachycardia or pre-existing bradycardia).

Interactions

The manufacturers of Esmya® (ulipristal acetate 5 mg), which is used for the treatment of severe symptoms of uterine fibroids, advise avoiding concomitant use of a progestogen intrauterine system. ¹⁶

Complications ¹⁶

For complications associated directly with the insertion process, including perforation, expulsion and lost threads, see the separate Intrauterine contraceptives (IUCD and IUS) - management article.

Altered or abnormal bleeding¹⁷

Irregular bleeding and spotting are common in the first six months with an LNG-IUD. Explain to women that 90% will experience reduced menstrual flow ultimately and some will be amenorrhoeic.

The FSRH has produced guidance on the assessment and management of problematic bleeding on hormonal contraception, including the LNG-IUD. While they recommend assessment following at least three months of persistent bleeding after insertion of LNG-IUD, they make the point that this is an arbitrary cut-off point, since persistent bleeding is common in the first six months following insertion of LNG-IUD.

For full details of their recommendations, see the separate Intermenstrual and postcoital bleeding article.

The decision to investigate early will depend on a number of factors including the risk of STIs, previous bleeding pattern, concerns of the woman and concurrent symptoms such as pelvic pain, post coital bleeding, or dyspareunia.

• <3 months from insertion - exclude STIs, check cervical screening history and consider the need for a pregnancy test and a clinical examination to check the threads. Where pain, discharge or lost threads occur in addition to bleeding, this requires further investigation to exclude expulsion, perforation or infection.

• >3 months from insertion (although the guidance notes that LNG-IUD-related bleeding is common up to six months) - perform a clinical examination where there is persistent bleeding, any new symptom or changed bleeding pattern, failed medical treatment, non-participation in the cervical screening programme or if requested by the woman. Abnormal clinical findings should be managed appropriately. Where findings are normal, but the woman is aged over 45 years or has risk factors for endometrial cancer, refer for further investigation (eg, ultrasound, hysteroscopy, endometrial biopsy).

Hormonal symptoms

• Acne, headaches, breast tenderness and nausea are reported by LNG-IUD users but these do not differ significantly from copper IUD users, and usually settle with time.

• Serum LNG levels with a LNG-IUD are lower than with oral or subdermal administration of progestogen but there is wide individual difference, possibly explaining the variation in experience of hormonal side-effects.

Mood changes

Depression has been reported, although most studies do not suggest a causative link. Women should be advised to consult their GP if they develop depressive symptoms.

Pregnancy and ectopic pregnancy

• Absolute rates of ectopic pregnancy are lower than with no contraception, because the total number of pregnancies is significantly reduced. However, if a woman does become pregnant with a LNG-IUD in place, the risk of an ectopic may be as much as one-third (compared to around 1.1% in pregnancies without an intrauterine device) and so an urgent scan is needed to locate the pregnancy. ²

• Women who become pregnant must be counselled regarding the increased risk of second-trimester miscarriage, infection and preterm delivery if the device remains in situ, and that removal reduces these outcomes but is associated with a small risk of miscarriage. Removal of a device in a woman who wishes to keep the pregnancy is usually done in secondary care.

Pelvic infection

• This is most strongly related to the insertion procedure and to the background risk of STIs.

• There is a six-fold increase in risk of PID in the first 21 days following insertion, but the absolute risk is low - only 0.54% of women who have an intrauterine device fitted will have PID in the 90 days after fitting.

• If pelvic infection is suspected in a woman using a LNG-IUD, it should be treated in the usual way.

• The device does not routinely need to be removed, but this can be considered if symptoms do not start to resolve within 72 hours or if the woman wishes it.

• Women should be followed up and their partners treated where appropriate. Sexual health risk assessment and counselling should be offered.

Actinomyces-like organisms (ALOs)

• ALOs are commensals of the female genital tract and have been identified in women with and without intrauterine contraception

• Their role in infection in women using intrauterine contraception is not clear

• If ALOs are seen on a swab or smear, removal of the device is not indicated if the woman is asymptomatic.

• If symptoms of pelvic pain occur in conjunction with the presence of ALOs, other causes of infection should be considered and removal of the device may be advisable.

• ALOs are less commonly seen on smears now than in the past, since the smear programme started using primary HPV testing.

Cancer

The LNG-IUD is associated with a possible very small increase in the risk of breast cancer, although the evidence is mixed. ²

Removal and return of fertility

Evidence suggests that normal fertility returns as soon as a LNG-IUD is removed. It can, however, take some months for regular menses to resume. ¹⁶

Where pregnancy is desired

The LNG-IUD can be removed at any time.

Where pregnancy is not desired¹⁸

• The LNG-IUD should be removed with menstruation or, if there has been no unprotected sexual intercourse in the previous seven days, at other times.

• Where the LNG-IUD is to be exchanged, intercourse should be avoided for the previous seven days in case re-insertion fails.

• When switching to a pill, remove after seven consecutive pills, or use barrier methods for the first seven days after a switch to the combined pill and the first two days after a switch to the desogestrel progesterone only pill. The LNG-IUD should be kept for seven days after any intercourse without a condom, unless it is overlapped with the pill.

• When switching to the depot or implant progestogen methods, remove the LNG-IUD after seven days of use of the new method.

Postmenopausal removal ²¹⁹

• If inserted after the age of 45 years, the 52mg LNG-IUD (any brand) may be used until menopause.

• Similarly, if any LNG-IUD is being used in the management of menorrhagia (and not for contraception or with oestrogen replacement therapy), it can be retained beyond the licensed duration of use if bleeding patterns are acceptable.

Dr Mary Lowth is an author or the original author of this leaflet.