Implanon is a birth control (contraceptive) implant for women. Implanon is a flexible plastic rod about the size of a matchstick that is placed under the skin of the upper arm. It releases a low, steady dose of a progestational hormone to thicken cervical mucus and thin the lining of the uterus (endometrium). Implanon typically suppresses ovulation as well.

A newer version of Implanon also is available. It's called Nexplanon and it's radio opaque. This means it can be seen on X-ray, which is useful for checking the location of the implant. Implanon and Nexplanon are the only contraceptive implants with Food and Drug Administration (FDA) approval available in the U.S.

Implanon offers effective, long-term contraception. Among various benefits, Implanon:

  • Can be removed at any time, followed by a quick return to fertility
  • Eliminates the need to interrupt sex for contraception or seek partner compliance
  • Provides relief from menstrual pain (dysmenorrhea) and pelvic pain caused by endometriosis

Implanon isn't appropriate for everyone, however. Your health care provider may discourage use of Implanon if you:

  • Are allergic to any components of the implant
  • Are overweight or obese
  • Have had serious blood clots, a heart attack or a stroke
  • Have hepatic tumors or liver disease
  • Have known or suspected breast cancer or a history of breast cancer
  • Have undiagnosed abnormal genital bleeding

Although the label for Implanon says it shouldn't be used by women with a history of blood clots, it isn't clear whether Implanon affects the risk of blood clots. The warning comes from studies of combination birth control pills that contain the same progestin as is used in Implanon.

Many experts believe progestin-only contraceptives have a significantly lower risk of these types of complications. However, the progestin in Implanon is a metabolite of desogestrel, which when used in oral contraceptives, appears to be associated with an increased risk of blood clots compared with pills with other formulations. Once again, it is not clear if this risk would be significant when the progestin is used alone as in Implanon, as opposed to when it's used with estrogen in an oral contraceptive.

In addition, tell your health care provider if you have a history of:

  • An allergic reaction to anesthetics or antiseptics
  • Depression
  • Diabetes
  • Gallbladder or kidney disease
  • Headaches
  • High blood pressure
  • High cholesterol or triglycerides
  • Seizures or epilepsy

Implanon doesn't offer protection from sexually transmitted infections (STIs).

Less than 1 out of 100 women who use Implanon for one year will get pregnant. If you do conceive while using Implanon, there's a higher chance that the pregnancy will be ectopic — when the fertilized egg implants outside the uterus, usually in a fallopian tube.

Side effects associated with Implanon include:

  • Abdominal or back pain
  • Acne
  • An increased risk of noncancerous ovarian cysts
  • Changes in vaginal bleeding patterns, including absence of menstruation (amenorrhea) — although irregular bleeding may lessen within three to nine months
  • Decreased sex drive
  • Dizziness
  • Hair loss
  • Headaches
  • Mild insulin resistance
  • Mood swings and depression
  • Nausea or upset stomach
  • Potential interaction with other medications
  • Sore breasts
  • Vaginal inflammation or dryness
  • Viral infections
  • Weight gain

Your health care provider will evaluate your overall health and do a pelvic exam before inserting Implanon. He or she will determine the appropriate timing for the insertion of Implanon based on your menstrual cycle and your previous birth control method. You may need to take a pregnancy test and use a nonhormonal backup method of contraception for one week.

A backup method of contraception may not be necessary if you previously:

  • Used no contraception and have Implanon inserted during the first five days of your menstrual cycle, even if you're still bleeding
  • Used combination birth control pills and have Implanon inserted within seven days of taking your last active pill
  • Used the minipill and have Implanon inserted while taking active pills
  • Used a contraceptive injection (Depo-Provera) and have Implanon inserted the day your next injection is due
  • Used Implanon or an intrauterine device (IUD) and have Implanon inserted the day your previous device is removed
  • Used a vaginal ring (NuvaRing) and have Implanon inserted during the seven-day ring-free period
  • Used a skin patch (Ortho Evra) and have Implanon inserted during the seven-day patch-free period

Implanon insertion is typically done in a health care provider's office. The actual procedure takes just a couple of minutes, though preparation will take about 15 minutes.

During the procedure

You'll lie on your back with the arm that will receive the implant bent at the elbow and positioned near your head. Your health care provider will locate a groove between the biceps and triceps muscles on the inner side of your upper arm. He or she will inject a local anesthetic and then use an applicator to insert the device just beneath your skin, above your large blood vessels and nerves. Inserting the device too deeply will make removal difficult.

After the procedure

Your health care provider will feel your arm to confirm the presence of Implanon and have you do the same. If necessary, he or she may also use an ultrasound to confirm that the device has been inserted. Your health care provider will cover the insertion site with a small bandage. He or she may also apply a pressure bandage to minimize bruising. You can remove the pressure bandage in 24 hours. Keep the small bandage clean and in place for three to five days.

It's common to experience some degree of bruising, pain, scarring or bleeding at the insertion site.

Contact your health care provider if you have:

  • Breast lumps
  • Heavy, prolonged vaginal bleeding
  • Signs or symptoms of a blood clot in your leg, such as persistent pain and swelling in your calf
  • Signs or symptoms of a stroke, such as a sudden severe headache, problems with vision or speech, or numbness in an arm or leg
  • Signs or symptoms of jaundice, such as yellowing of the skin or whites of the eyes, especially with fever, fatigue, loss of appetite, dark urine or light-colored bowel movements
  • Signs or symptoms of an infection at the insertion site, such as tenderness, redness, swelling or discharge
  • Symptoms of depression, such as trouble sleeping, fatigue or feeling sad
  • Signs or symptoms of pregnancy at any time after Implanon is inserted

Removal

Implanon can prevent pregnancy for up to three years. It must be removed and replaced at the three-year point to continue offering pregnancy protection.

Your health care provider may recommend removing Implanon earlier if you:

  • Develop jaundice
  • Experience significant depression

To remove the device, your health care provider will inject a local anesthetic in your arm beneath the implant. He or she will make a small incision in your skin and will push the implant toward the incision until the tip is visible and can be grasped with forceps. Your health care provider will then pull out the implant, close the incision and apply a pressure bandage. Implanon removal typically takes less than five minutes.

If you choose, a new device can be implanted as soon as the original device is removed. Be prepared to use another type of contraception right away if you don't have a new device inserted.

Jan. 21, 2012