The IUS is similar to the IUD, as it is a small plastic device which is placed in the womb to prevent pregnancy.
However, the IUS also contains the hormone progestogen. The IUS is a long-term contraceptive which can be left in place for up to five years.
How does it work?
The progestogen released by the IUS works in several ways to prevent a woman from getting pregnant; firstly it thickens cervical mucus to prevent sperm from being able to reach an egg, secondly it thins the lining of the womb so that if an egg was fertilised it would not be able to implant, and lastly for some women it may stop eggs from being released (ovulation).
How effective is it?
The IUS is over 99 per cent effective at preventing pregnancy.
What are the advantages?
It can be fitted at any time, you don’t have to remember to take anything and it does not interrupt sex. Also, your periods will probably be shorter and lighter, and for some women may stop completely. And your periods and fertility will return quickly if the IUS is removed.
What are the downsides?
When you have the IUS fitted you may experience side effects, such as breast tenderness, spotty skin and headaches. Also, you may not have regular periods, which some women find annoying or worrying.
There is a small chance that you could develop an infection after having the IUS fitted, or, very rarely, that having the IUS fitted may perforate your womb. This is not likely if the doctor or nurse fitting your IUS has lots of experience.
Things to bear in mind
It needs to be fitted by a specially trained doctor or nurse, and having it fitted may be uncomfortable or even a little painful. Also, if you have picked up a sexually transmitted infection from unprotected sex and have an IUS fitted you could get a pelvic infection.
Most importantly, the IUS does not provide any protection against HIV or other sexually transmitted infections like a condom does.
Where can I get it from and how much does it cost?
The IUS is available free on the NHS. You can only get it on prescription. This can be from your GP, another GP who you have registered with for family planning services, a practice nurse or a family planning or young person's clinic.