Contraception: hormone implant

by | Babies and Pregnancy

A contraceptive hormone implant is a device that is used to prevent pregnancy. The implant is a small rod that is inserted beneath the skin, usually on the inside of the upper arm. It provides very reliable contraception for up to 3 years. The brand name of the hormone implant available in Australia is Implanon NXT.

How does Implanon NXT work?

Implanon NXT is a small plastic rod 40 mm long and 2 mm thick (about the size of a matchstick). It contains etonogestrel, a synthetic progestogen, which is steadily released into the bloodstream over time. This hormone mimics the natural female sex hormone progesterone.

It works by stopping ovulation (the release of an egg from your ovaries). It also thickens the cervical mucus (mucus made in the cervix – the lower part of the uterus) so that sperm can’t penetrate it and enter the uterus.

Effectiveness at preventing pregnancy

Hormone implants are extremely effective at preventing pregnancy. Once the implant is in place, you don’t need to remember to do anything, so there are no problems relating to incorrect use. The failure rate of hormone implants during the first year of use is 0.05 per cent. 

The failure rate of hormone implants during the first year of use is 0.05 per cent. That means that less than one woman in every 100 will become pregnant in the first year of using a hormone implant.

Advantages of the hormone implant

Some of the advantages of the contraceptive hormone implant are that it:

  • is highly effective at preventing pregnancy;
  • provides long-term contraception (implants last for up to 3 years);
  • is cost-effective;
  • allows fertility to return quickly after removal;
  • offers immediate protection against pregnancy if inserted in the first 5 days of the menstrual cycle (when you have your period);
  • can be used while breast feeding;
  • does not interfere with sexual spontaneity; and
  • can help with painful periods and premenstrual syndrome, and periods may stop altogether in some women.


Some of the disadvantages of the hormone implant are that it:

  • is only available on prescription;
  • can only be inserted (and removed) by a specially-trained doctor or nurse;
  • may cause irregular vaginal bleeding or/and spotting;
  • does not help protect against sexually transmitted infections (STIs);
  • may cause bruising or soreness of the arm after insertion;
  • may cause a small scar;
  • cannot be used by certain women, including those with severe liver disease, breast cancer, unexplained uterine bleeding or blood clots (deep vein thrombosis); and
  • should not be used by women taking certain medicines (including anti-seizure medicines, certain antibiotics and St John’s wort) that reduce the effectiveness of the implants.

How is it used?

The hormone implant should be put in between the first and fifth day of your menstrual cycle (day one is the first day of bleeding). When inserted during day 1-5 of your cycle (while you have your period), you are protected against pregnancy straight away. If the implant is inserted at another time in your cycle, you will need to use a back-up form of contraception (such as condoms) for 7 days.

Your doctor will want to be sure that you are not pregnant before inserting an implant, so may ask you to do a pregnancy test before insertion to confirm you are not pregnant.

Who can insert the implant?

You can have Implanon NXT inserted by a general practitioner (GP) who is trained in the use of this device. Alternatively, a doctor or nurse at a Family Planning Clinic can put the implant in for you.

Having the hormone implant inserted

Implanon NXT is inserted under the skin of the inside of your upper arm (your left arm if you are right-handed, and vice versa) using a special applicator.

Before inserting the implant, your doctor may give you a small injection of local anaesthetic. They will then use the applicator to insert the implant under the skin. A bandage will be applied after insertion, but no stitches are needed. The area may be a little sore and bruised for a few days after insertion.

Once the implant is in place, you should be able to feel it under the skin.

A follow-up appointment at 3 months is usually arranged to check the implant and whether you are experiencing any side effects. Health checks at least once a year will be recommended after that.

If you decide at any time that you want to try to get pregnant, the implant can be removed by your doctor and your periods should return quickly.

Having the hormone implant removed or replaced

Hormone implants should be removed or replaced within 3 years. A new implant can be inserted at the same site if you wish to continue using hormone implants for contraception.

Before removal, your doctor will inject some local anaesthetic in the skin near the implant. A small incision (cut) in the skin will be made to remove the implant. No stitches are needed. Sometimes a small scar forms on the skin.

Implants are usually easily removed but in rare circumstances removal can be difficult. If this is the case, may need to see a specialist for removal.

Side effects

Implanon NXT may be associated with side effects such as:

  • unpredictable bleeding patterns (including frequent periods, prolonged periods, light or no periods);
  • breast tenderness;
  • acne;
  • headaches;
  • mood changes; and
  • weight gain.

Unpredictable bleeding and spotting is very common, especially in the first few months of use. Your doctor may prescribe another medicine (such as the combined pill) in the short term to help reduce this side effect.

Bleeding may become more predictable after the first 3-4 months of use. However, up to a quarter of women request removal of their hormone implant within 12 months due to unpredictable bleeding.

Talk to your doctor if side effects are a problem for you.

Implanon and other medicines

There are some medicines that can reduce the effectiveness of hormone implants. St John’s wort (a herbal preparation) and some medicines used to prevent seizures should generally not be taken if you have a contraceptive implant. Antiviral medicines used to treat HIV/AIDS and hepatitis C can also be a problem. Talk to your doctor about any medicines you are taking.

Hormone implants: should I get one?

A hormone implant may be a good choice for you if you want extremely effective contraception that you don’t have to think about. But there are some side effects, so you should talk to your doctor about the pros and cons of the hormone implant to help you decide if it’s a good choice for you.