Progestogen-Only Intrauterine Device Pregnancy: Not to be used during an existing or suspected pregnancy. If accidental pregnancy occurs with the system in situ, exclude ectopic pregnancy and remove the system as soon as possible — there is a high risk of pregnancy complications (abortion, preterm labour, infection and sepsis); removal or uterine probing may itself cause spontaneous abortion. An increased risk of virilising effects in a female foetus cannot be excluded. Breast-feeding can be continued during use.

Levonorgestrel Intrauterine System

Brand names: Mirena (52 mg), Kyleena (19.5 mg), Jaydess (13.5 mg)

A progestogen-releasing intrauterine system providing long-acting reversible contraception, treatment of heavy menstrual bleeding, and endometrial protection during oestrogen therapy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One intrauterine delivery system releasing levonorgestrel 20 micrograms/24 hours, inserted into the uterine cavity

Route: Intrauterine — inserted by a healthcare professional using aseptic technique (strongly recommended that insertion is only by professionals experienced in IUS insertion and/or trained in the specific insertion procedure)

Frequency: Single insertion; effective for eight years for contraception and has demonstrated efficacy for three years for heavy menstrual bleeding. Remove or exchange after 8 years of use, or earlier if heavy or bothersome menstrual bleeding returns.

Max: One system in situ at a time; remove or exchange after 8 years of use

SPC §4.2 (Benilexa One Handed 20 micrograms/24 hours Intrauterine Delivery System). TIMING OF INSERTION: insert within 7 days of the onset of menstruation — contraceptive protection is provided on insertion and no back-up is needed. If insertion within 7 days of onset of menstruation is not possible, or the woman does not have regular menses, it may be inserted at any time in the cycle provided prior conception can be reliably excluded; immediate contraceptive protection is then not reliably ensured, so a barrier method should be used or vaginal intercourse avoided for the next 7 days. POSTPARTUM: postpone until the uterus is fully involuted and not earlier than 6 weeks after delivery; if involution is substantially delayed, consider waiting until 12 weeks postpartum. AFTER FIRST-TRIMESTER ABORTION: can be inserted immediately, no back-up contraception needed. REPLACEMENT: can be replaced by a new system at any time in the cycle, no back-up needed. SWITCHING from another method (e.g. combined hormonal contraceptive, implant): insert immediately if it is reasonably certain the woman is not pregnant; if more than 7 days since menstrual bleeding began, abstain or use additional contraception for 7 days. FOLLOW-UP: re-examine at 4 to 6 weeks after insertion to check the threads and confirm correct position; physical examination alone may not exclude partial perforation and ultrasound may be considered. Exclude pregnancy before insertion. NOT suitable as a post-coital contraceptive. REMOVAL: remove by gently pulling on the threads with forceps; if threads are not visible, ultrasound-guided removal with narrow forceps may be needed, sometimes requiring cervical dilatation or surgical intervention; examine the removed system to ensure it is intact. If continuing the method, a new system can be inserted immediately after removal; otherwise removal should be within 7 days of the onset of menstruation, or a barrier method used from at least 7 days before removal. PAEDIATRIC: not studied in patients below 16 years of age and should not be used before menarche (no numeric paediatric dose in the SPC). ELDERLY: no indication for use in postmenopausal women. HEPATIC: contraindicated in liver tumour or other acute or severe liver disease. Single use only — do not resterilise; discard if the sterile seal is broken.

Dose adjustments

Renal

Not studied in women with renal impairment (SPC §4.2 special populations).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known or suspected pregnancy
Current or recurrent pelvic inflammatory disease; lower genital tract infection; postpartum endometritis; infected abortion during the past three months
Cervicitis, cervical dysplasia; suspected or confirmed uterine or cervical malignancy; undiagnosed abnormal uterine bleeding
Congenital or acquired abnormality of the uterus, including fibroids if they distort the uterine cavity
Liver tumour or other acute or severe liver disease
Current or suspected hormone-dependent tumours such as breast cancer
Acute malignancies affecting the blood or leukaemias, except when in remission; recent trophoblastic disease while hCG levels remain elevated
Conditions associated with increased susceptibility to infections
Hypersensitivity to the active substance or to any of the excipients

Side effects

Very common: uterine/vaginal bleeding including spotting, oligomenorrhoea and amenorrhoea
Very common: benign ovarian cysts (enlarged follicles diagnosed in 12% of subjects in clinical trials; most asymptomatic and resolve within three months)
Headache; migraine; dizziness
Abdominal pain/discomfort; nausea
Acne; alopecia; hirsutism
Pelvic pain, dysmenorrhoea, vaginal discharge, breast tenderness; uterine perforation; pelvic inflammatory disease; ectopic pregnancy; device expulsion

Clinical monograph

How it works

Locally released levonorgestrel thickens cervical mucus, suppresses endometrial proliferation, and in some women inhibits ovulation.

Prescribing in practice

Exclude pregnancy and current pelvic infection before insertion, and counsel that it does not protect against sexually transmitted infections.
It is a first-line option for heavy menstrual bleeding and provides endometrial protection in women taking oestrogen.
Avoid in current breast cancer, undiagnosed vaginal bleeding, active pelvic infection, and significant active hepatic disease.

Monitoring

Review a few weeks after insertion to confirm correct placement and exclude infection or expulsion, then periodically as clinically appropriate.

Counselling the patient

Irregular bleeding or spotting is common at first and usually settles, with many women eventually having very light or absent periods.
Seek review if you develop severe pelvic pain, abnormal discharge or fever, or cannot feel the threads.
Remember it does not protect against sexually transmitted infections.

Evidence & guidelines

NICE guidance on heavy menstrual bleeding (NG88) recommends the levonorgestrel intrauterine system as a first-line treatment option.

Reference: NICE NG88 (HMB 2018); Gupta et al. NEJM 2013 (LNG-IUS vs norethisterone for HMB); FSRH Intrauterine Contraception Guideline (2023); SPC Mirena; UKMEC 2016; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators