The contraceptive implant is a very effective, convenient and safe form of contraception. A small operation under local anaesthetic is needed to insert the implant under the skin. Each implant lasts three years.
What is the contraceptive implant?
A contraceptive implant is a device that is put under the skin in order to offer you an even dose of contraception without you having to take a daily pill. It contains a progestogen hormone. Nexplanon® is the only contraceptive implant that you can be prescribed in the UK at present. However, there are other devices available elsewhere in the world. Nexplanon® is a small tube 40 mm long and 2 mm wide (about the size of a hair grip).
How does the contraceptive implant work?
The progestogen hormone in the implant is called etonogestrel. It is released into the bloodstream at a slow, steady rate. The progestogen works mainly by stopping the release of the egg from the ovary (ovulation). It also thickens the mucus which forms a mucous plug in the neck of the womb (cervix). This stops sperm getting through to the womb (uterus) to fertilise an egg. It also makes the lining of the womb thinner. This means that if an egg were to fertilise, it would not be likely to be able to attach to the womb.
How effective is the contraceptive implant?
Around 1 in 3,000 sexually active women using the implant will become pregnant each year. When no contraception is used, more than 2,400 in 3,000 sexually active women become pregnant within one year. This 'failure rate' is similar to but even lower than that of the intrauterine contraceptive device (IUCD), the intrauterine system (IUS) and sterilisation, which also have very low failure rates. In fact in most studies of the implant no women became pregnant at all.
What are the advantages of using a contraceptive implant?
- You do not have to remember to take a pill every day.
- You only have to think about contraception every three years.
- It does not interfere with having sex (intercourse).
- It can be used when breast-feeding.
- Period pain is usually reduced and periods are usually lighter.
- It can usually be used by women who cannot take pills that contain oestrogen.
- It may help to protect against pelvic infection, as it makes the mucous plug in the neck of the womb (cervix) thicken. This may help to prevent bacteria from travelling into the uterus.
What are the disadvantages of using a contraceptive implant?
- Insertion and removal with local anaesthetic are required.
- The release of progestogen will usually cause changes to the pattern of periods.
- During the first year, irregular bleeding is common. Periods usually settle back into a regular pattern after the first year, but may remain irregular.
- In some women periods can be heavier and/or more frequent, particularly in the first year following insertion.
- In some women periods become infrequent and light, or even stop all together. One in five women with the implant have no bleeding.
- If you do develop irregular bleeding or bleeding after having sex (intercourse) after having the implant inserted then you should inform your doctor. Irregular bleeding can occasionally be due to another reason - for example, an infection, which may need to be treated.
Who cannot have a contraceptive implant?
Your doctor or family planning nurse will discuss any current and past diseases. Some diseases may mean you cannot use progestogen-based contraceptives such as Nexplanon®, but this is uncommon.
Are there any side-effects with the contraceptive implant?
- If side-effects do occur they tend to develop in the first few months only. They often go after 3-6 months if the implant remains in.
- As with all hormonal contraceptives, some women report side-effects such as breast discomfort, fluid retention and increase in acne. However, some women actually find an improvement in their acne.
- As with all small cuts to the skin, there is a slight risk of a wound infection.
- The possible effects on periods are mentioned above.
- There is no evidence that women with an implant gain weight.
- The implant is not associated with an altered sex drive or mood changes.
- The implant does not cause any thinning of your bones.
How is the contraceptive implant put under the skin?
- It is put in the inner side of the upper arm.
- It is usually first inserted within five days of a period starting, to ensure that you are not pregnant. It is effective immediately.
- An injection of local anaesthetic is used to numb the skin. A special needle is used to place the implant under the skin. The wound is dressed and will soon heal just like any other small cut.
- The area around the implant may be bruised and sore for a few days, but this soon goes.
Do I need to be seen again after the contraceptive implant is inserted?
You do not need to be routinely seen by your doctor or nurse after having your implant inserted. However, you can return at any time to discuss any problems. You should see your doctor or nurse if any of the following occur:
- You cannot feel your implant.
- Your implant appears to have changed shape.
- You notice any change in your skin or have any pain in the area around the implant.
- You become pregnant.
- You develop irregular bleeding or bleeding after intercourse.
When is the contraceptive implant taken out?
A replacement is needed every three years if you wish to continue with this form of contraception. It requires a small operation under local anaesthetic to remove the old device and put in a new one.
The implant can be taken out at any time if you request removal. It loses its effect immediately after being removed. So, if you do not want to become pregnant, you must use another form of contraception immediately afterwards.
There is no delay in your fertility returning after the implant is removed.
Do other medicines interfere with the contraceptive implant?
Some prescribed medicines may interfere with the progestogen (mainly some used for epilepsy and tuberculosis). Tell the doctor or pharmacist that you have a progestogen implant if you are prescribed another medicine. It is unlikely that a medicine bought without the need for a prescription will interfere with the effectiveness of Nexplanon®. If in doubt, ask the pharmacist.
St John's wort
The herbal remedy St John's wort is available without prescriptions from pharmacies and health food stores. It is commonly used for headaches, anxiety, low mood and pre-menstrual syndrome. Unfortunately taking St John's wort decreases the effectiveness of hormonal contraceptives, including nexplanon. It does so by increasing the breakdown of the contraceptives hormones by your body. This could result in an unplanned pregnancy, so women using hormonal contraceptives to prevent pregnancy should not take St John's wort.
You should always tell your doctor if you are taking over the counter medications or health food preparations before being prescribed anything, as interactions between these compounds and prescribed medication are not uncommon.
Further help & information
Dr Tim Kenny
Dr Mary Lowth
Prof Cathy Jackson