Although the majority of women with an IUS have no problems, the following may occasionally occur as side-effects or consequences
You may have irregular bleeding for the first three to six months. This usually settles down. It is usually a light “spotting” of blood which women can find a nuisance. Heavier bleeding can occasionally occur. If you experience heavy bleeding or a marked change in bleeding pattern you should discuss this with your doctor. It may mean the IUS has come out without you realising, or could be a sign of infection or pregnancy.
There is a risk of worsening an existing infection of the womb (pelvic infection) when you have an IUCD inserted. A check for infection of the vagina or neck of the womb (cervix) may be advised by taking a sample (swab) before an IUCD is inserted. The doctor or nurse fitting the device may ask you some ntimate questions about your sex life in order to determine whether it might be sensible to do a swab or urine tests. If there is thought to be a risk, you may be given antibiotics at the time the IUCD is fitted.
A pregnancy developing outside the womb (uterus), usually in the Fallopian tube, is known as an ecoptic pregnancy and is very unusual with the IUS. This is because the IUS protects against this sort of pregnancy. However, if you do develop one-sided tummy (abdominal) pain with bleeding you should discuss this with a doctor.
The IUS may come out without you noticing (expulsion). This happens to 1 woman in every 20. It usually happens in the first year, particularly in the first three months, during your period. It seems it is slightly more likely to happen if it has happened to you before.
It is a good idea to check you can feel the threads of the IUS after your period. If you cannot feel them, you should use extra precautions such as a condom, until your doctor or nurse has checked the IUS is still there. If the IUS has come out in the previous few days you may need emergency contraception. If the IUS could have come out more than a few days previously, and you are sexually active, the doctor or nurse will need to make sure you are not already pregnant before fitting another one or starting alternative contraception.
Damage to the womb
The fitting of an intrauterine contraceptive can (very rarely) make a small hole in the womb – this is called perforation. It protrudes through the wall of the womb and can escape into your tummy. This happens in fewer than 2 women per 1,000, usually at the time of fitting. It can cause pain, but this is not usually severe and often there is no pain. The main symptom is not being able to feel the threads. Your womb will heal on its own but you may need an operation to remove the IUS from your tummy.
You should tell your doctor or nurse if you can no longer feel the threads of your IUS. This can mean perforation has occurred. However, far more commonly it means that the threads are tucked up inside the neck of the womb (cervix). Rarely, it can be because the threads have come off the IUS. An ultrasound scan will be carried out to find a lost IUS. If ultrasound does not find the IUS, an X-ray will be ordered.
Hormonal side-effects are uncommon. The progestogen released by the IUS mainly stays around the womb and very little gets into the bloodstream. So hormone side-effects are less common than with the progestogen-only pill and the contraceptive injection or implant. If side effects do occur, they tend to develop in the first few months. They tend to ease and go
Examples of possible side-effects include:
Reduced sex drive (libido).
Increase in acne.
A slight increase in breast size – this can occur in the first few months but is usually temporary.
There is no evidence that women with an IUS put on weight.
The IUS does not protect you against any sexually transmitted infections (STIs). If you have a new sexual partner, you should always use a condom, until you have both been checked for any STI.