Health Centres - Implanon
How does it work?
Implanon is a long-acting progesterone-only contraceptive implant that contains the active ingredient etonogestrel. Etonogestrel is a synthetic form of the naturally occurring female sex hormone, progesterone. It prevents pregnancy in two ways.
In a woman's normal menstrual cycle, an egg matures and is released from the ovaries (ovulation). The ovary then produces progesterone, preventing the release of further eggs and priming the lining of the womb for a possible pregnancy. If pregnancy occurs, progesterone levels in the body remain high, maintaining the womb lining. If pregnancy does not occur, progesterone levels in the body fall, resulting in a menstrual period.
Etonogestrel tricks the body processes into thinking that ovulation has already occurred, by maintaining high levels of the synthetic progesterone. This prevents the release of eggs from the ovaries and is the main way in which etonogestrel prevents pregnancy.
Etonogestrel also affects the natural mucus at the neck of the womb (cervix). It increases the thickness of this mucus, making it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of an egg, leading to pregnancy, is less likely.
Implanon is a small plastic implant containing etonogestrel that is inserted under the skin of the upper arm. (The area will be numbed first using a local anaesthetic.) The plastic implant slowly releases etonogestrel into the bloodstream.
Implanon will prevent pregnancy from the time it is inserted. It will provide contraception for three years if left in place, but can be removed at any time by your doctor or family planning nurse, for example if you decide you want to have a baby, or if you have unacceptable side effects. The implant doesn't dissolve in the body and should not be left in place any longer than three years. After the implant is removed you are no longer protected against pregnancy and your normal menstrual cycle will rapidly return.
If you have not been using another hormonal contraceptive, the implant should be inserted between days one to five of your menstrual cycle (day one is the first day of your period). If you are changing from another hormonal contraceptive to Implanon, your doctor or family planning nurse will tell you when the implant needs to be inserted.
What is it used for?
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Contraception in women aged 18 to 40 years.
Warning!
- After your implant is inserted, your doctor should, together with you, feel for the actual presence of Implanon in your arm. In case of doubt you will have to use a condom until the doctor and you are absolutely sure that the implant has been inserted.
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