The Contraceptive Implant -- Implanon™

Implanon™ is a thin, flexible plastic implant about the size of a cardboard matchstick.  It is inserted under the skin of the upper arm. 

How the Implant Works

The implant contains progestin.  Progestin is a synthetic hormone similar to the progesterone made by a woman's ovaries.  It works in two ways.  It keeps the ovaries from releasing eggs (ovulation).  It also thickens the cervical mucus, preventing sperm from joining with an egg.  In theory, it could prevent implantation of a fertilized egg, but it has not been proven that it does.                         

How Well the Implant Works

Results of long-term studies will not be available for some time, but researchers estimate that Implanon will be up to 99.9 percent effective for up to three years. 

Certain medicines and supplements, including the antibiotic rifampin, St. John’s wort, certain anti-fungal drugs that are taken orally for yeast infections, and certain drugs used to treat mental illness, seizures, or HIV, may reduce the effectiveness of the implant.

How the Implant is Used

After taking your medical history and giving you a physical exam, the clinician will numb a small area of your arm with a painkiller.  The implant is inserted under the skin.  Insertion takes only a few minutes.  Protection against pregnancy is immediate if you get the implant during the first five days of your period.  Otherwise, use an additional method of contraception for the first seven days.

Do not have the implant inserted if there is a chance that you are pregnant.  Be sure to tell your clinician if you think there is any chance that you are.  After insertion, be sure to tell any health care provider you may see that you are using Implanon.

The implant should be removed when it is no longer effective (three years after insertion) because although it stops working, it may interfere with menstrual cycles.  It can also be removed anytime earlier.  The clinician will numb the area with a painkiller and will usually make one small cut to remove the implant.  Removal usually takes just a few minutes, but it generally takes longer than insertion.  A new implant may be inserted at this time.  Pregnancy can happen anytime after the implant is removed.

Advantages of the Implant

• ability to become pregnant returns quickly when use is stopped
• can be used while breastfeeding 
• can be used by women who cannot take estrogen
• gives continuous long-lasting birth control without sterilization
• no medicine to take every day
• nothing needs to be put in place before vaginal intercourse

A woman should not use the implant if she

• cannot tolerate irregular bleeding

• cannot put up with loss of her period 

• has a sensitivity to the ingredients in it 

• has had or might have breast cancer

• is or might be pregnant

Some implant users may need close medical supervision if they have

• blood clots in the arteries or veins 
• a history of liver disease, such as hepatitis, abnormal results on liver function tests, or benign or malignant liver tumors
• a history of severe depression
• unexplained bleeding from the vagina

Possible Disadvantages of the Implant

Irregular bleeding is the most common side effect for women using the implant.  Periods become fewer and lighter for most women — in time, they may stop altogether.  Some women will have longer and heavier periods.  Some may have increased light spotting and breakthrough bleeding.

However, these side effects are more common in the first six to 12 months of use.  The longer a woman uses the implant, the more likely she will stop having menstrual periods.  About one out of three implant users have no periods after one year of use.

Less common side effects include

• acne
• change in appetite
• change in sex drive
• cysts on the ovaries
• depression
• discoloring or scarring of the skin over the implant
• dizziness
• hair loss
• headache
• nausea
• nervousness
• pain at the insertion site
• sore breasts

The implant cannot reduce the risk of sexually transmitted infections.  Latex and female condoms can.

Warning Signs for the Implant

Serious problems are rare.  Tell your clinician immediately if

• You have arm pain.
• You have bleeding, pus, and increasing redness or pain at site insertion.
• You have a migraine or other severe headache. 
• You have a new lump in your breast.
• You have severe pain in the stomach or abdomen.
• You have unusually heavy or prolonged vaginal bleeding.
• The implant comes out.

Information on this website is for educational and reference purposes only and should not be interpreted as specific medical advice.

Copyright © 2006

Women Physicians

Ob-Gyn Medical Group

650.988.7550