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Implanon® (Implant)

This is new on the market and can only be administered by doctors and nurses who have been trained to insert it. Effectiveness rates are difficult to asses because of its newness. To date, however, no women taking part in the research trials has become pregnant. A check up 3 months after the insertion of the implant should be undertaken and the implant should not be left in place for longer than 3 years.

Implanon’s active ingredient is Etonogestrel Organon, which is a synthetic form of the naturally occurring female sex hormone, progesterone. In a woman’s normal menstrual cycle, an egg matures and is released from the ovaries (ovulation), which 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.

The etonogestrel implant is injected under the skin of the arm to slowly release the hormone into the body, maintaining a high level of the hormone in the blood. It provides contraception for 3 years but can removed at any time by your doctor or family planning nurse.

Etonogestrel works by tricking the body into thinking that ovulation has already occurred, by maintaining high levels of the synthetic progesterone which prevents the release of eggs from the ovaries. It also increases the thickness of this mucus by affecting the natural mucus at the neck of the womb (cervix) making it more difficult for sperm to cross from the vagina into the womb.

This medicine will not protect you or your partner from sexually transmitted diseases, so you should use a condom to provide this protection. In women who are heavier than normal, the contraceptive effect of this implant may not last for 3 years. Also consult your doctor if you are to be immobilized for a long time due to surgery or illness.

Implanon should be used with caution in people with a history of:

  • blood clots in the blood vessels (thromboembolism)
  • breast cancer
  • decreased liver function
  • diabetes
  • high blood pressure (hypertension)
  • a tendency to suffer from irregular yellowish-brown skin patches on the face and other areas often due to pregnancy or the use of oral contraceptives (chloasma) – avoid exposure to the sun or ultraviolet radiation whilst using this implant

Implanon should not be used in:

  • a type of cancer affected by progestogens
  • blood clots in the blood vessel (thrombosis) that may travel through the vessels (thromboembolism)
  • current or previous severe liver disease
  • pregnancy or suspected pregnancy (may be present in breast milk)
  • vaginal bleeding of unknown cause
  • allergy to one or any of its ingredients (stop using this medicine and inform your doctor or pharmacist immediately if you feel you have experienced an allergic reaction)
no interruption between foreplay and intercourseSide effects*
no inconvenience of a pillimplants may be slightly visible
implant site is comfortable and barely visible
effective within 24 hours after insertion
effectiveness rates high

*Side effects include:


  • abdominal pain
  • abnormal or irregular menstrual bleeding
  • acne
  • breast tenderness or pain
  • bruising at site of implant
  • changes in sex drive
  • depression
  • difficult and painful menstruation (dysmenorrhea)
  • hair loss (alopecia)
  • headache
  • increased risk of breast cancer
  • irritation, pain or itching at site of implant
  • rise in blood pressure
  • weight gain

The etonogestrel implant’s contraceptive effectiveness may be reduced if taking the following medicines:

  • Rifamycins such as Rifabutin and Rifampicin
  • antiepileptic medicines such as Carbamazepine, Phenytoin, Phenobarbital and Primidone
  • Griseofulvin

Inform your doctor if you are taking any of these medicines as a barrier method of contraception such as condoms may be required. “Hormonal Contraception: Pills, Implants & Injections” by Joseph W. Goldzieher is a useful and informative book for any woman considering or using hormonal contraceptive methods.

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