Levonorgestrel intrauterine system: do the contraceptive benefits outweigh the risks in light of new FSRH guidance?

BACKGROUND

The levonorgestrel-releasing intrauterine system (LNG-IUS) is a long-acting reversible contraceptive. In 2023, the Faculty of Sexual and Reproductive Healthcare (FSRH) extended its recommended duration of use from 5 to 8 years. This change underlines the need to re-examine the balance of efficacy and risks associated with LNG-IUS.

AIM: To systematically review evidence on contraceptive effectiveness, safety, and acceptability of LNG-IUS, and evaluate its alignment with updated FSRH guidance.

METHOD: A systematic search of MEDLINE, Embase, PsycINFO, CINAHL, and Scopus (April 2025) identified studies reporting efficacy, satisfaction, discontinuation, and adverse outcomes (expulsion, bleeding, amenorrhoea, perforation, treatment-emergent adverse events). Eighteen studies were included and appraised using validated risk-of-bias tools.

RESULTS

LNG-IUS showed very high contraceptive efficacy (Pearl Index 0.13; pregnancy rates <1%), with satisfaction rates above 85%. Expulsion and perforation rates remained low (<5% and <2%). Amenorrhoea was more common than other side effects (10-37%), a clinically important outcome requiring discussion in counselling. Treatment-emergent adverse events varied (12-31%) but were mostly mild. Discontinuation ranged widely (25-73%), primarily for non-medical reasons. Long-term data confirm effectiveness and safety up to 8 years, supporting the FSRH guideline change.

CONCLUSION

This review provides strong evidence that LNG-IUS is a safe, effective, and acceptable contraceptive for up to 8 years. While side effects such as amenorrhoea may influence continuation, overall benefits outweigh risks. These results highlight the importance of counselling and reinforce the clinical relevance of the new guideline change for women seeking reliable long-term contraception.