First-lineMirena, Levosert
Levonorgestrel IUS
Progestogen intrauterine system
Mirena — long-acting reversible contraception, also HMB treatment.
Intrauterine
First-line for
- LARC contraception
- Heavy menstrual bleeding
- Endometrial protection on HRT
Mechanism
Local progestogen → endometrial atrophy, mucus thickening; minimal ovulation suppression.
Mirena facts
- 52 mg levonorgestrel
- Effective 8 years (contraception)
- HMB licence 5 years
- Insert any time if not pregnant
Dosing
- Insertion
- Anytime if pregnancy excluded
- Postpartum
- ≥4 weeks (perforation risk earlier)
Contraindications
- AbsoluteCurrent pelvic infection / STI
- AbsolutePregnancy
- AbsoluteUterine cavity distortion
Side effects
- Irregular bleeding (first 6 months)
- Amenorrhoea ~20% at 1y
- Functional cysts
- Expulsion 5%
Fetal & maternal notes
- • Safe in breastfeeding (UKMEC 1 from 4 weeks).
Key interactions
Clinical pearls
- 💡 Perforation 1/1000 — higher if <36 weeks postpartum or breastfeeding.
- 💡 Threads check 6 weeks then yearly.
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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