The hormonal coil — known medically as the levonorgestrel intrauterine system, or LNG-IUS — is a small T-shaped device placed inside the womb. It does two quite different jobs well: it is one of the most effective contraceptives available, and it is one of the best treatments we have for heavy periods.

How long it lasts

In Sri Lanka, the hormonal coil is advised to be replaced after 5 years, whichever reason you have it for. The latest evidence — reflected in the extended licence issued in 2024 — supports its use for up to 8 years when used purely as contraception.1,5 In practice:

  • For contraception: the advice here is 5 years, though the latest evidence supports longer use.
  • For treating heavy periods, or for womb protection as part of HRT: it is changed after 5 years in every case.

This matters. The longer figure applies only to contraception — if you have the coil for heavy bleeding, the treatment effect may wear off after 5 years. Follow the replacement date your doctor gives you, and make a note of when yours is due.

How it works

The device releases a small amount of a progestogen hormone directly into the womb. It thins the lining of the womb, thickens the mucus at the neck of the womb so sperm cannot pass, and affects sperm movement.

Because the hormone acts mainly inside the womb, very little reaches the rest of your body. This is why it causes fewer hormonal side effects than tablets or injections.

As contraception

The hormonal coil is over 99% effective — fewer than 1 in 100 women will become pregnant across its entire lifespan. Like the implant and the copper coil, it does not depend on you remembering anything, which is why it performs so well in real use.

Fertility returns as soon as it is removed. It is safe while breastfeeding, and suitable for women who cannot take oestrogen.

As treatment for heavy periods

This is where the hormonal coil is genuinely transformative for many women. By thinning the womb lining, it substantially reduces menstrual blood loss. Many women find their periods become very light, and a good number stop having them altogether.

In the standard treatment pathway for heavy periods, tablets are tried first, and the hormonal coil is the usual next step. For many women it removes the need for surgery entirely — including hysterectomy. See our guide to heavy, irregular and painful periods.

Its other uses

  • Endometrial hyperplasia — thickening of the womb lining
  • Womb protection during HRT — used alongside oestrogen to keep the womb lining safe
  • Endometriosis and adenomyosis — helps with associated pain in many women

What fitting is like

Fitting takes a few minutes in a clinic room, without general anaesthesia. A speculum is used, as for a smear test, and the device is passed through the neck of the womb.

Most women find this uncomfortable and some find it painful — usually strong period-like cramping that peaks briefly and then eases. Taking a simple painkiller beforehand helps. If you are anxious about it, ask about pain relief options; it is a reasonable thing to raise.

What to expect in the first months

Be prepared for irregular bleeding and spotting for the first 3 to 6 months. This is expected, it is not a sign that anything is wrong, and it is the main reason women give up on the coil before it has had a chance to work.

If you can get through those first months, bleeding usually settles into a much lighter pattern than you had before — which is the whole point of it. If the spotting is troublesome, see your doctor rather than simply enduring it.

Other possible effects include headaches, breast tenderness, acne and mood changes, though these are less common than with methods that act on the whole body.

Afterwards

Two fine threads pass into the top of the vagina, and you can feel for them to check the device is in place. See a doctor if you cannot feel them, or if you have persistent pain, unusual discharge, fever, or bleeding after sex.

Who it may not suit

It may not be suitable if you have an untreated pelvic infection, unexplained vaginal bleeding, certain womb abnormalities, or some cancers. Your doctor will go through your history first.

The bottom line

The hormonal coil is a rare thing — a treatment that solves two problems at once, giving excellent contraception while making heavy periods much lighter. It is advised for 5 years in Sri Lanka whatever the reason you have it, so follow the replacement date your doctor gives you. The first few months of irregular spotting are worth getting through.

References

  1. Faculty of Sexual and Reproductive Healthcare. CEU statement: Mirena 52 mg LNG-IUD — extension of licence for contraception to 8 years. London: FSRH; 2024. Available from: https://www.fsrh.org/Public/Public/Documents/fsrh-ceu-statement-mirena-8-years-contraception-jan-2024.aspx
  2. National Institute for Health and Care Excellence. Heavy menstrual bleeding: assessment and management. NG88. London: NICE; 2018. Available from: https://www.nice.org.uk/guidance/ng88
  3. National Health Service. Intrauterine system (IUS) [Internet]. NHS; [cited 2026 Jul 22]. Available from: https://www.nhs.uk/conditions/contraception/ius-intrauterine-system/
  4. Jensen JT, Lukkari-Lax E, Schulze A, Wahdan Y, Serrani M, Kroll R. Contraceptive efficacy and safety of the 52-mg levonorgestrel intrauterine system for up to 8 years: findings from the Mirena Extension Trial. Am J Obstet Gynecol. 2022;227(6):873.e1–873.e12.
  5. NHS Fife. Mirena use extended [Internet]. NHS Fife; 2024 [cited 2026 Jul 26]. Available from: https://www.nhsfife.org/services/all-services/sexual-health/contraception/the-coil/mirena-use-extended/