Intrauterine System

The hormone thickens the mucus at the entrance to the womb preventing sperm getting through and thins the lining of your womb preventing implantation of a fertilised egg. It may also stop ovulation (eggs being released from the ovaries) in somewomen.

Extremely effective (>99%). Less than 1 in 500 women will become pregnant using the device.
Contraception lasts for 3-5 years unless you want it removed earlier.
Periods usually become lighter, shorter and sometimes less painful.
Intrauterine system users, by one year, commonly do not experience any bleeding.
Can be used by women who have never had a baby.
Fertility returns as soon as it is removed.
There will be no need to take pills, interrupt sex or requirement to attend clinic regularly after insertion.
Is not affected by other medications.

No protection against sexually transmitted infections (STIs) - condoms advised.
Insertion can be slightly uncomfortable. Local anaesthetic is offered.
Can cause unpredictable bleeding pattern for the first three months, but after this time bleeding becomes infrequent and irregular, or stops altogether.
Can become displaced or fall out (expulsion) but this is uncommon (5 in 100) and you can do checks yourself to make sure it’s in place.
Small risk of pelvic infection for up to 3 weeks after insertion. This risk is reduced by having a sexual health screen prior to the fitting.
Very small risk of perforating the womb or cervix (1 in 500 risk).

Sexual Health services. A preliminary appointment is usually required before fitting this method to discuss the method fully, screen for infections and schedule a fitting date.
Family planning clinics
Some GP practices