The hormonal coil (the IUS or Mirena) is made of plastic and releases a small amount of progestogen hormone which is similar to one of the body's own hormones.
It's put into the womb by a doctor or nurse and lasts up to 5 years.
The IUS can be wonderful in helping heavy or painful periods.
- Lasts up to 5 years
- No need to remember pills or patches
- It doesn’t interrupt sex
- It’s extremely good at preventing pregnancy
- Periods are usually lighter and less painful
- It's a low level of a very safe hormone
- Often suitable for people who can't take oestrogen
- It's usually quick and easy to take out
- Suitable for any age
- Having an IUS fitted can be painful
- Some have irregular bleeding
- The IUS can come out (1 in 20 users)
- STI check needed before putting it in
- No protection against STIs
- Sometimes mood changes, skin problems or breast tenderness
- IUD through the wall of the womb when it's put in (fewer than 2 in 1000)
- Pregnancy outside the womb (ectopic pregnancy) - possible but very rare
The IUS is great if pills are a nuisance to remember
It lasts up to 5 years, and is not affected by other medicines, vomiting or diarrhoea
The IUS contains a lower level of hormones
The IUS has the lowest level of hormone of all the hormonal methods of contraception
The IUS does not cause infertility
Fertility returns to normal after having the IUS taken out. It’s important to know that it’s less easy to get pregnant as you get older – it’s naturally harder to get pregnant over the age of 35 (although this can definitely still happen!). Find out more about infertility here
Partners won’t feel the IUS during sex
Some partners do notice the threads during sex, but the threads can be trimmed so they are out of the way
Nobody knows that you have an IUS
The IUS can be kept secret since it's right inside the womb
The body doesn't need a period once a month
The IUS stops the lining of the womb from building up and the womb lining stays thin – blood doesn’t build up inside, and it can help people feel more energetic if they are not losing iron each month in a period. Find out more about periods here
Many people use the IUS for its benefits even if they don't need it for contraception
It can be fantastic for period pain and lighter periods. It can be used to treat these symptoms in Endometriosis.
The IUS can also be used as the progesterone part of Hormone Replacement Therapy (HRT).
The IUS can come out especially after periods in the first three months (1 in 20 users)
It's important to check the threads (feeling for them inside the vagina after every period)
Good to know
The IUS usually makes periods lighter, shorter and less painful. Some will have no periods at all, especially if they have been using it for a while.
Some people get irregular bleeding which is not harmful but can be a nuisance - it's worth seeking advice if this happens.
The IUS can be painful to put in, but is usually easy to take out.
How much effort is the IUS?
The IUS is put in by a doctor or nurse at a GP surgery, sexual health clinic or family planning clinic. It takes about 15 to 20 minutes to put in.
The fitting can be painful, and it’s common to have some pain and bleeding for a few days after.
It's important to make sure you are not already pregnant when it's put in. Clinics will advise about this. Find out more about where to get an IUS here
Once fitted, the IUS is effective for between 3 and 5 years, depending on the type.
How effective is the IUS?
The IUS is more than 99% effective – if 100 people use it for a year, less than one will have an unplanned pregnancy.
How does it work?
The IUS releases a small amount of progestogen hormone which thickens the fluid around the neck of the womb (which stops sperm getting to an egg), and makes the lining of the womb thinner so that a fertilised egg can’t settle and grow.