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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.

A contraceptive implant is a small, flexible rod about the size of a matchstick. The implant contains a progestogen hormone which provides contraception without you having to take a daily pill.

The rod is put under the skin on your arm. The only contraceptive implant currently available in the UK is Nexplanon® (there are other devices available elsewhere in the world).

Nexplanon® is 40 mm long and 2 mm wide. That is, about the size of a normal matchstick.

The contraceptive implant is over 99% effective. Only around 1 in 2,000 sexually active women using the implant will become pregnant each year, often because they were actually pregnant at the time of insertion.

If an implant is put in during the first five days of your period, you are protected against pregnancy immediately.

If an implant is put in at any other time during your cycle, you are not protected until seven days have passed. You will need to use additional contraception if you wish to have sexual intercourse during this time.

You should only have an implant put in if it is certain that you are not already pregnant. You will still need to use contraception such as condoms to protect against sexually transmitted infections (STI's).

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. It also thickens the cervical mucus which forms a 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 (implantation).

In order for you to get pregnant you need all of these things to be working (ovulation, sperm getting through the cervix, and implantation). The contraceptive implant blocks all three stages.

The contraceptive implant is fully effective for three years, but it stops being effective if it is removed. After three years, if you want to continue using this method of contraception, you will need a new implant.

The contraceptive implant is about the size of a matchstick and is placed under the skin of the inner side of your upper arm. A trained doctor or nurse will put the implant in.

  • An injection of local anaesthetic is used to numb the skin.
  • A special device is used to place the implant under the skin. The wound is dressed and will soon heal just like any other small cut.

The procedure only takes a few minutes. The area around the implant may be bruised and tender for a few days.

A trained doctor or nurse must take your implant out. The procedure is similar to putting the implant in.

  • An injection of local anaesthetic is used to numb the skin.
  • A tiny cut is made in your skin the implant is gently pulled out.
  • A dressing will be put on your arm which should be left in place for a few days. You may also have Steristrips® (paper stitches)

Implanon v

Implanon - contraceptive implant
Vera de Kok, CC BY-SA 4.0 , via Wikimedia Commons

Occasionally, an implant is difficult to feel under the skin, in which case you may be referred to a specialist centre to have it removed with the help of an ultrasound scan. If you want to carry on using an implant, the doctor or nurse can put a new one in at the same time. If you do this there will be no break in your contraceptive protection.

The implant can be taken out at any time if you request removal. It loses its effect immediately after being removed.

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You can have an implant fitted at any time in your menstrual cycle if it is certain that you are not pregnant.

  • If the implant is put in during the first five days of your period you will be protected against pregnancy immediately.
  • After day 5 and if you haven't had unprotected sexual intercourse (UPSI) since your last period, the implant can be inserted immediately but you should avoid sexual intercourse or use a barrier method of contraception (such as condoms) for 7 days.
  • If you have had unprotected sexual intercourse since your last period you may need a pregnancy test and emergency contraception. You should discuss this with your clinician.

If you have recently had a baby the implant can be put in at any time after the birth. If the implant is inserted on or before day 21, your contraceptive protection starts straightaway. (You can't become pregnant in the first 21 days after delivery, so as long as you have it inserted any time up to day 21 you are protected.)

If it is fitted later than this and you have had unprotected sexual intercourse, you may need a pregnancy test and emergency contraception. You should discuss this with your clinician.

If you have had a termination of pregnancy or a miscarriage the implant can be put in at the same time, or in the first five days, and is effective immediately.

Most side-effects caused by the contraceptive implant occur when you first start using the implant. They are not usually severe.

The most common side-effects are:

  • Changes in your periods (see below).
  • Fluid retention and breast tenderness.
  • Acne: your skin may temporarily worsen, although it can also improve.
  • Itching or bruising after implant insertion.
  • Mood swings or low mood.
  • Weight gain.
  • Breast tenderness.

The contraceptive implant does not usually cause altered sex drive (libido), but some women who have experienced other side-effects also say that their sex drive was reduced.

Most women experience changes in their periods with a contraceptive implant.

  • Most commonly, the periods will be lighter and less regular.
  • Some women find that their periods stop altogether with the implant (amenorrhoea).
  • A few women have longer, irregular periods, which can be heavy.
  • Some women experience mood swings at first, which can be like pre-menstrual mood swings (PMS).

If you have prolonged bleeding with the contraceptive implant your doctor or nurse can prescribe extra hormone tablets to suppress the bleeding until it settles by itself. This way you keep the contraceptive cover, and the periods will usually settle down over time. This usually happens within three months of having the implant inserted.

There is no strong evidence that the contraceptive implant makes women put on weight. Progesterone can do this, but more so when taken in higher doses than you receive from the contraceptive implant. It can also cause fluid retention initially - which will make your weight go up - but this is usually due to fluid rather than fat.

Women who use some forms of hormone-based contraception appear to have a small increase in long-term risk of being diagnosed with breast cancer compared to women who don't use hormonal contraception. It is not known if this is also true of the contraceptive implant. There is not enough evidence to know whether the contraceptive implant causes any change in the risk of ovarian, endometrial or cervical cancer.

Apart from bruising and soreness, it is possible, although very unusual, to get a localised infection in your arm when the implant is put in. Insertion of the implant can leave a small scar.

It is important to be able to feel the implant under the skin after insertion. There is a small risk of insertion error in which the implant is not actually inserted by the procedure.

After taking levonorgestrel (Levonelle®) as emergency contraception the implant can be inserted immediately. You should avoid sex or use a barrier method of contraception (such as condoms) for 7 days. In addition you should take a pregnancy test 3 weeks or so after the time you had unprotected sex.

If you took ulipristal acetate (ellaOne®) the implant should be inserted 5 days after taking the tablet. You should avoid having unprotected sex or use a barrier method of contraception (such as condoms) until the implant is inserted and for 7 days after. You should also take a pregnancy test no sooner than 3 weeks after the last time you had unprotected sex.

Yes, an implant can be used when breastfeeding. The implant will not affect your milk production and will not harm your baby.

Although breastfeeding does slightly reduce the chance of another pregnancy, it is not a reliable contraceptive and it is possible to become pregnant whilst breastfeeding.

Some medicines may make an implant less effective. This includes some medicines used in epilepsy, HIV and tuberculosis, and St John's wort (a herbal remedy often used to treat headaches, mood disturbances and premenstrual syndrome).

These medications reduce the effectiveness of the implant by increasing the rate at which your body disposes of the hormone in the blood. If you are using one of these medicines you will need to consider a different or additional contraceptive method.

The implant is not affected by common antibiotics, or by an attack of diarrhoea or being sick (vomiting).

Most women can have an implant fitted but there are a few exceptions. You should not have a contraceptive implant put in if you think you might be pregnant, or if you don't want to use a contraceptive method that might affect your periods.

You also should not use the contraceptive implant if:

  • You are taking medicines which might interfere with the implant.
  • You have some types of severe heart or liver disease.
  • You have breast cancer. If you have had breast cancer in the past then the implant would usually also not be recommended.
  • You are currently experiencing unexplained vaginal bleeding.
  • You have a hereditary blood disorder called porphyria.

There are some conditions which, if you have them, mean that you could use the contraceptive implant, but a different method might be more suitable for you. These include:

If you want to try for a baby, you need to have the implant removed. Your periods will return to normal, although it can be up to three months before you get back to your old rhythm. However, it is possible to get pregnant before you have your first period.

Start pre-pregnancy care such as taking folic acid, stopping smoking and considering any regular medication you take beforehand. You can ask your doctor or nurse for further advice.

The contraceptive implant has to be fitted by a specially trained nurse or doctor. This service may be offered at your local GP surgery and, if it is, how to arrange it will probably be explained on their website. Alternatively, a family planning, sexual health or community gynaecology clinic will do this for you. You can find details of services in your area in the UK online.

In the UK the contraceptive implant is free of charge.

All contraceptive services are completely confidential. You will not need an internal examination, a breast examination or a smear before you can have a contraceptive implant. In some cases you may need a pregnancy test to be certain that you are not already pregnant.

Dr Mary Lowth is an author or the original author of this leaflet.

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