IUS (Intrauterine system)

How effective is it?

Over 99 per cent effective. Less than one woman in 100 will get pregnant over
five years.

What are the advantages?

Works for five years but can be taken out sooner.
Periods usually become lighter, shorter and sometimes less painful or periods may stop altogether.
You don’t have to think about contraception for as long as the IUS is in place.
When the IUS is removed your fertility will return to normal.

What are the disadvantages?

Irregular bleeding or spotting is common in the first six months.
Some women report having acne, headaches and breast tenderness.
Very small chance of getting an infection during the first 20 days after insertion.
May get ovarian cysts.

Anything else I should know?

If fitted after 45 it can stay in place until the menopause.
Women are taught to check the IUS is in place.
Can be useful for women with very heavy and/or painful periods.
A check for any existing infection is usually advised before an IUS is put in.
Not affected by other medicine.

How does it work?

It makes the lining of your uterus thinner so it is less likely to accept a fertilised egg.
It also thickens the mucus in your cervix. This makes it difficult for sperm to move through it and reach an egg.
In some women it stops the ovaries releasing an egg (ovulation), but most women who use an IUS continue to ovulate.