Approved by the Food and Drug Administration (FDA) in 2006, Implanon is a birth control method that offers continuous protection against pregnancy for up to three years. The matchstick-sized rod is implanted just under the surface of your skin.

What is Implanon?
Implanon is a hormonal form of birth control that prevents pregnancy. Made of soft medical polymer, an Implanon implant is  1.5 inches long and 0.08 inches wide. Because Implanon is placed underneath the surface of your skin, your body receives a steady dose of progestin (specifically etonogestrel). This helps to make the contraception much more effective, as your body never misses a dose. While this type of birth control is long term, fertility will typically return once the implants are removed. Although Implanon is relatively new to the U.S., about 2.5 million women have used it worldwide since 1998.

How is Implanon Implanted?
Insertion of Implanon is a fairly straightforward procedure that is performed in your doctors office. First, the area on the underside of your upper arm will be sterilized and a local anesthetic may be used to numb the area. Using a special applicator, your doctor will then insert the Implanon rod into your skin. Once the rod has been implanted, you should not be able to see it. However, both you and your doctor should feel the area to make sure it has been inserted properly.

Before you receive Implanon, your doctor may have you take a pregnancy test. You will also need to read over and sign a consent form before the implant can be placed in your arm. Once the procedure is finished, your doctor will give you a User Card that states the date the implant was put in and the date at which it should come out. Although Implanon has shown to be effective for three years, you can have the implant removed before this time. An Implanon rod should not be left in for more than three years.

Women who are not currently using other hormonal birth control methods will likely have Implanon inserted between the first and fifth day of menstrual bleeding. If you are using the birth control pill, a birth control ring, or the birth control patch, Implanon will be inserted the first day of your seven-day hormone free period.

How Does Implanon Work?
Each Implanon rod contains 68mg of etonogestrel. This hormone is steadily released into your system while you have the implant. During the first year of use, about 60 to 70 micrograms are released into your system daily. However, this amount decreases over time until, in the third year, you are only receiving 25 micrograms a day.

Similar in function to birth control pills, the increase of hormones in your system initially works to prevent pregnancy by stopping ovulation. Implanon also protects against pregnancy by changing your cervical mucus, which may hinder sperm from reaching an egg. Additionally, Implanon appears to change the uterine lining, which may stop a fertilized egg from implanting.

How Effective is Implanon?
Because of the steady dose of hormone, the effectiveness of Implanon is quite high with less than one woman in 100 getting pregnant a year. However, women who were overweight or obese were not included in Implanon studies. Just how effective Implanon is in these women is not known.

Complications and Side Effects

While Implanon is a simple and effective birth control, it has a number of side effects and complications associated with it, many similar to Implanon’s predecessor Norplant.

Side Effects
The most common side effects reported during studies of Implanon included:

  • Weight gain
  • Acne
  • Menstrual disturbances
  • Clinical depression
  • Mood swings
  • Headaches

In addition to the side effects listed above, common side effects reported in clinical trials included:

  • Breast tenderness
  • Abdominal or period pain
  • Viral infections (i.e. sore throat, cold)
  • Vaginitis
  • Anxiety
  • Nausea
  • Dizziness
  • Back pain
  • Change in libido
  • Pain at site of injection
  • Pain

Menstrual disturbances were quite a nuisance for many women and resulted in one in 10 women discontinuing the use of Implanon during studies. A variety of menstrual problems were experienced by women using Implanon, such as amenorrhea, spotting, irregular periods or prolonged bleeding. In fact, menstrual problems are so common, manufacturers of Implanon write in their patient information leaflet that women should anticipate their periods becoming irregular and unpredictable while they are using this contraceptive. In other words, unlike other side effects, menstrual disturbances do not eventually subside.

Other, rare side effects were also reported during studies on Implanon and included:

  • Increased hair growth on face and body
  • Vision problems and irritation in contact lens wearers
  • Darkening spots of skin, mainly affecting the face

Complications During Insertion and Removal
Some complications may occur when insertion of Implanon takes places. This can include some tenderness, swelling, redness and bruising of the implant area. In rare instances, the implant may fail to be inserted, either because the rod has fallen out of the applicator or because it was inserted improperly. It is also possible for the body to expel the implant, but again this is rare.

Other problems that may occur when Implanon is inserted or removed include:

  • Scarring
  • Formation of scar tissue around the implant
  • Infection
  • Need for surgical removal in hospital (rare)

Being unable to feel the implant, having a broken or damaged implant, experiencing troubles locating the implant or having an implant that has migrated slightly contributed to 1.7% of study participants having greater difficulty when their doctor removed their implant.

Recommendations for Use
Not every woman is suited to this contraception method. Women who prefer not to use hormonal contraceptives, either for personal or religious reasons, may want to consider other birth control options, such as a diaphragms or cervical caps.

Like other hormonal contraceptive methods, Implanon increases your risk of blood clots and other cardiovascular problems. Therefore, women who smoke are discouraged from using Implanon. This contraceptive is also not recommended for women who:

  • Are or may be pregnant
  • Have an allergy to the material or hormones used in the rod implant
  • Have a personal history of serious blood clots
  • Have a personal history of breast cancer
  • Have liver disease
  • Experience unexplained vaginal bleeding

While it is not thought that Implanon causes birth defects, it is recommended that you have the implant removed if you discover that you are pregnant. Implanon increases your risk of having an ectopic pregnancy. It can also increase your blood pressure, so it is important to go for regular check-ups with your doctor while using implanon to make sure your blood pressure remains at a healthy level.

Certain medications, like barbiturates, as well as herbal treatments, such as St. John’s Wort, can interfere with the effectiveness of Implanon. If you are being prescribed any medications or herbal remedies, be sure to tell your health care provider that you are using Implanon.

Implanon offers no protection against HIV or other STDs. In order to protect against STDs, it is important to correctly use condoms each time you have sex.

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