--- title: 'How Does The Hormonal IUD Work And What To Expect' slug: hormonal-iud-what-to-expect-mirena lifeStage: cycle category: Cycle medicalReviewer: 'Dr Shree Datta, Consultant Obstetrician and Gynaecologist ' reviewerId: 'https://blog.bloume.com/cycle/medical-board.md#dr-shree-datta' lastUpdated: '2026-07-24' primarySource: www.nhs.uk --- # How Does The Hormonal IUD Work And What To Expect The hormonal IUD, sometimes called the hormonal coil, is a small T-shaped device fitted inside your womb that releases a progestogen hormone locally. It is more than 99% effective at preventing pregnancy. Unlike the combined pill, it works mainly at the level of your womb rather than across your whole body. This article covers how it works, what happens to your periods, what to expect in the first few months, and what changes for cycle tracking. **Q: Will my periods stop completely with a hormonal IUD?** A: They may. Your periods often become much lighter and shorter, and for many they stop altogether, particularly after the first year. This is a common, safe outcome. In the first 3 to 6 months you are more likely to have irregular spotting before things settle. You may have heard the hormonal IUD can make your periods lighter or stop them altogether, and wondered what that actually feels like day to day. Understanding how a hormonal IUD works, what to expect in the early months, and how it sits differently in your body compared to the combined pill can help you have a more informed conversation with your GP or sexual health clinician. ## How the hormonal IUD works The hormonal IUD is a small, T-shaped plastic device fitted into your womb by a clinician. It releases a progestogen hormone directly into the womb and is more than 99% effective at preventing pregnancy. Depending on the type, it can stay in place for 3 to 8 years. Mirena, for example, is licensed in the UK for up to 8 years for contraception, while devices such as Kyleena and Jaydess work for shorter lengths of time. Your clinician can advise which device suits you. It works in three main ways. It thickens the mucus at your cervix, which makes it harder for sperm to reach an egg. It thins the lining of your womb, which makes it harder for a fertilised egg to settle in. And in some cases, it stops ovulation. The first two are the main effects. Ovulation carries on for most people who use it. ## What happens to your periods Because the progestogen thins your womb lining, there is less tissue to shed each cycle. Your periods often become much lighter, shorter, and less painful. For many, they stop altogether, particularly after the first year. When periods stop in this way, it is called amenorrhoea, and it is a common, safe outcome that fits how the device works. If your periods are heavy and that is part of why you are considering the hormonal IUD, it is worth raising with your GP or a sexual health clinician, who can advise whether it suits your situation. ## Spotting and irregular bleeding in the first months Irregular bleeding and spotting are common in the first 3 to 6 months after the device goes in. This is a known settling-in period as your body responds to the hormone, and it usually eases over time. This early irregular bleeding tends to come from the contraceptive method itself. > **WARNING**: If bleeding is heavy, carries on past 6 months, or you feel worried at any point, it is worth raising with your GP or sexual health service rather than waiting for your next routine appointment. ## How the hormonal IUD differs from the combined pill The hormonal IUD releases only a progestogen hormone, and it does this locally, right into your womb. The combined pill contains both oestrogen and progestogen, which absorb into your bloodstream and act across your whole body. That wider spread is why the pill can bring a broader range of hormonal effects, while the IUD's effects stay concentrated at your womb. The way each method works differs in an important way too. The combined pill mainly works by stopping ovulation, cycle after cycle. The hormonal IUD does not reliably stop ovulation, so you often keep ovulating. Its contraceptive effect comes mainly from thickening your cervical mucus and thinning your womb lining. Both methods are more than 99% effective when used correctly. Because the hormonal IUD does not contain oestrogen, it may suit you if you cannot use oestrogen-containing contraception. Whether it is right for you comes down to your own health history, and your GP or sexual health clinician can advise. ## What changes about cycle tracking with a hormonal IUD Because you often keep ovulating, the underlying hormonal rhythm of your cycle tends to carry on quietly in the background. The outward signs that cycle tracking usually leans on, though, change a lot. Your bleeding becomes light, irregular, or stops. Your cervical mucus changes are masked, because the device thickens that mucus as part of how it works. So tracking based on watching your bleeding or your cervical mucus is no longer a reliable guide to where you are in your cycle. Cycle tracking while you use the hormonal IUD does not give you contraceptive protection. The IUD itself does that. Tracking can still be useful for general body awareness, though it cannot work as a fertility awareness method alongside the IUD. You may still notice cyclical symptoms, such as the ones that come with premenstrual syndrome (PMS), because the hormonal shifts of your cycle can carry on underneath. Without a regular bleed to anchor those feelings to a phase, it can be harder to tell where you are in your cycle or to see symptoms coming. > **INFO**: If you are considering the hormonal IUD, speak to your GP or a sexual health clinic. They can talk through which device suits your circumstances, walk you through what the fitting involves, and answer questions about how it might affect your cycle. --- **Q: Will my periods stop completely with a hormonal IUD?** They may. Your periods often become much lighter and shorter, and for many they stop altogether, particularly after the first year. This is a common, safe outcome. In the first 3 to 6 months you are more likely to have irregular spotting before things settle. **Q: Does the hormonal IUD affect your hormones the same way the pill does?** No. The hormonal IUD releases progestogen locally into your womb, and only a very small amount reaches the rest of your body. The combined pill delivers both oestrogen and progestogen into your bloodstream, where they act across your whole body. The IUD also does not stop ovulation the way the pill does, so you often keep ovulating. **Q: Can you still track your cycle when using a hormonal IUD?** You can log symptoms, but the usual markers tracking leans on, like your bleeding pattern and cervical mucus changes, are altered a lot by the IUD. Tracking while you use the IUD cannot work as contraception, because the IUD itself gives you that protection. You may still notice cyclical symptoms such as PMS even without a regular period. **Q: Is the hormonal IUD suitable if you cannot take oestrogen?** Because it contains only progestogen and works locally, it is sometimes an option when oestrogen-containing contraception is not suitable. Whether it is right for you depends on your own health history, and that is a decision for a clinician. Speak to your GP or a sexual health service for a personal assessment. ### Clinical Sources - [www.nhs.uk](https://www.nhs.uk/contraception/methods-of-contraception/ius-hormonal-coil/what-is-it/) - [devonsexualhealth.nhs.uk](https://www.devonsexualhealth.nhs.uk/contraception/hormonal-iud/) - [uhcw.nhs.uk](https://www.uhcw.nhs.uk/download/clientfiles/files/Patient%20Information%20Leaflets/Women%20and%20Children_s/Gynaecology/Mirena%20Coil%20(IUS).pdf) - [uhcw.nhs.uk](https://www.uhcw.nhs.uk/download/clientfiles/files/Patient%20Information%20Leaflets/Women%20and%20Children_s/Gynaecology/Mirena%20Coil%20(IUS).pdf) - [Methods of contraception](https://www.nhs.uk/contraception/methods-of-contraception/) - [FSRH Guideline Combined Hormonal Contraception ](https://www.cosrh.org/Common/Uploaded%20files/documents/fsrh-guideline-combined-hormonal-contraception-october-2023.pdf) - [sh24.org.uk](https://sh24.org.uk/contraception/hormonal-coil/how-ius-works) - [sh24.org.uk](https://sh24.org.uk/contraception/hormonal-coil/how-ius-works) --- Reviewed by Dr Shree Datta, Consultant Obstetrician and Gynaecologist | [Medical Board](https://blog.bloume.com/cycle/medical-board.md) | July 2026