Mirena

Health and Nutrition > Medicines > M



How does it work?

Mirena is a contraceptive device that contains the active ingredient levonorgestrel. It is an intrauterine system (IUS) that is inserted into the womb in a similar way to a contraceptive coil. Once inserted it steadily releases the levonorgestrel into the womb (uterus). Levonorgestrel is a synthetic form of the female sex hormone, progesterone.

Levonorgestrel works by increasing the thickness of the natural mucus at the neck of the womb. This makes it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of an egg is less likely.

Levonorgestrel also prevents the womb lining (endometrium) from thickening each month in preparation to receive a fertilised egg. This stops any eggs that are fertilised from successfully implanting onto the wall of the womb, and prevents pregnancy in another way. Levonorgestrel may also prevent the release of an egg from the ovary (ovulation), but this does not necessarily occur in all women who use the IUS.

The device itself may also add to the contraceptive effect, in the same way that normal copper coils (IUDs) work due to their presence in the womb.

Mirena may be particularly useful for women needing contraception who also suffer from very long or heavy menstrual periods. Because the levonorgestrel prevents the womb lining from thickening, it reduces the amount of tissue that is shed each month as a menstrual period and makes periods lighter. Peroids may eventually stop while the IUS is in place.

The Mirena IUS should ideally be inserted in the first five days of your menstrual cycle (day one is the first day of your period). This will provide immediate protection against pregnancy. The IUS can be inserted at other times in your cycle if your doctor is sure you are not pregnant, but you will need to use an extra method of contraception (eg condoms) for the first seven days after it is inserted.

Mirena can also be prescribed for women taking oestrogen-only hormone replacement therapy (HRT) following the menopause. In women with an intact womb, oestrogen HRT stimulates the growth of the womb lining (endometrium), which can lead to endometrial cancer if the growth is unopposed. A progestogen, such as the levonorgestrel in Mirena, is used to oppose oestrogen's effect on the womb lining and reduce the risk of cancer, though it does not eliminate this risk entirely. If a woman has had her womb surgically removed (a hysterectomy), endometrial cancer is not a risk, and a progestogen is not necessary as part of HRT, unless the woman has a history of endometriosis.

What is it used for?

- Contraception
- Heavy or prolonged menstrual periods with no known cause
- Protection from overgrowth of the womb lining (endometrial hyperplasia) in women taking oestrogen-only hormone replacement therapy (HRT) following the menopause

Warning!

- A gynaecological examination should be performed before insertion of this IUS. This will include a breast exam and the doctor will also check to find the position and size of your womb, that you are not pregnant and that you have no infections or sexually transmitted diseases. Further examinations should be performed six weeks after insertion and then yearly (or more frequently if clinically needed).
- If you have any heart valve defects, you may be given antibiotics when the IUS is inserted or removed, in order to prevent inflammation of the heart valves and sac surrounding the heart (endocarditis).
- The insertion and removal of the IUS can be a little painful and you may want to take a painkiller such as paracetamol beforehand. It can also cause bleeding. If you get severe pain, or if any bleeding continues, you should let your doctor know, because the IUS might have penetrated the wall of the womb (‘perforation’).
- An IUS may be expelled from the uterus without the woman noticing it, although an increase in menstrual bleeding or pain may warn you of this. The effectiveness of the IUS is lost if it is expelled, and is also decreased if it is partially expelled. You should be shown how to check the removal threads on your IUS when it is inserted, to make sure it is still in place. Consult your doctor if you cannot find the threads.
- You may experience irregular bleeding or spotting in the first few months after Mirena is inserted. After this your periods will usually settle down and become shorter and lighter, or may stop alltogether. If you don't have a period within six weeks of your previous period, you should consult your doctor, to ensure that the IUS has not been expelled and you are not pregnant. However, it may simply be that the IUS is causing your periods to stop.
- If you experience lower abdominal pain, particularly in combination with missed periods, or a recurrence of menstrual bleeding if your periods had stopped, you should consult your doctor.
- The IUS should be removed if you experience recurrent pelvic infection or inflammation of the womb lining (endometritis), or if an infection does not respond to treatment within a few days.
- If pregnancy does occur while the IUS is in place, the IUS should be removed.

There may be an increased risk of miscarriage or premature labour if the pregnancy then continues.
- You should inform your doctor immediately if you experience any of the following symptoms while you have the Mirena coil fitted: migraine or severe headaches; stabbing pains and/or unusual swelling in one leg; pain on breathing or coughing; sudden breathlessness; sudden severe chest pain; sudden weakness or numbness affecting one side or part of the body; increase in blood pressure; yellowing of the skin or eyes (jaundice); severe abdominal complaints; severe depression; or if you become pregnant.
- The IUS provides effective contraception for five years and must be removed by your doctor after this time if you are using it for contraception or heavy periods. (It can be removed earlier than this if required.) If you have had Mirena fitted as part of your HRT you should have it removed after four years, because there are only limited data on its womb protective effect after this time.
- This IUS will not protect you against sexually transmitted infections, so you may still need to use condoms as well.

Use with caution in

.

- History of migraine or severe headaches
- Known or suspected cancers in which growth of the cancer is stimulated by sex hormones, such as breast cancer
- Leukaemias or other malignancies affecting the blood that are in remission (use only after specialist consultation)
- Women receiving long-term treatment with oral or injected corticosteriods, eg prednisolone, hydrocortisone
- History of ovarian cysts
- Women with risk factors for disease of the arteries, eg high cholesterol levels
- Angina
- High blood pressure
- Diabetes
- Smokers
- Jaundice
- Women with a blood clot in a vein of the leg (deep vein thrombosis) or in the lungs (pulmonary embolism), or a past history of these conditions
- Blood disorders that increase the risk of blood clots in the blood vessels, eg antiphospholipid syndrome, factor V Leiden
- Epilepsy
- Postmenopausal women whose wombs have shrunk significantly as a result of the menopause

Not to be used in

- Known or suspected pregnancy
- Vaginal bleeding of unknown cause
- Abnormalities of the womb (uterus)
- Uterine fibroids that distort the uterus
- Uterine cancer
- Cervical cancer
- Inflammation of the cervix (cervicitis)
- Abnormal tissue in the cervix (cervical dysplasia)
- Genital infections
- Current or recurrent pelvic inflammatory disease
- Inflammation of the womb lining following birth of a child (postpartum endometritis)
- Infection following an abortion in the last three months
- Recent pregnancy with abnormal placental tissue that produces large amounts of the pregnancy hormone hCG (trophoblastic disease) - unless the hCG levels are back to normal
- Current or previous severe disease of the arteries, eg that has caused a stroke or heart attack
- Women with artificial heart valves or structural heart defects, who have previously had an infection of the heart valves and sac surrounding the heart (bacterial endocarditis), or severe pelvic infection
- Acute or severe liver disease
- Liver cancer
- People whose immune systems have a decreased ability to fight infection and disease, eg due to conditions such as AIDS or immunodeficiency syndromes or treatment with medicines such as chemotherapy or immunosuppressants
- Leukaemias or other malignancies affecting the blood, unless they are in remission.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. . If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

- This IUS should not be inserted if you are or could be pregnant. If you do fall pregnant while the IUS is in place, you should consult your doctor immediately and the IUS should be removed. There may be an increased risk of miscarriage or premature labour if the pregnancy then continues. Seek further medical advice from your doctor.
- Levonorgestrel can pass into breast milk, but only in small amounts, particularly with the dose released from Mirena in the womb. This does not seem to have any adverse effects on a nursing infant, and Mirena can be used to provide contraception for women who are breastfeeding. It should not be inserted until six weeks after the birth of the child. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine.

Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

- Change in menstrual bleeding, such as frequent, prolonged or heavy bleeding, spotting, lighter bleeding, irregular bleeding or stopping of bleeding
- Development of fluid filled sacks (cysts) in the ovaries
- Excessive fluid retention in the body tissues, resulting in swelling (oedema)
- Weight gain
- Headache
- Depression
- Nervousness
- Mood swings
- Nausea
- Lower abdominal pain
- Back pain
- Breast pain
- Painful menstrual bleeding
- Acne
- Vaginal discharge
- Inflammation of the cervix
- Hair loss or hair growth
- Skin reactions such as rash or itching
- Genital infections, including pelvic inflammatory disease
- Decreased sex drive
- Migraine
- Abdominal bloating

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. . For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care or attention by a qualified practitioner. The materials in this web site cannot and should not be used as a basis for diagnosis or choice of treatment. Conditions for use

© Copyright 1998 - 2009 NetDoctor.co.uk - All rights reserved