The following adverse reactions reported with the use of hormonal contraception are discussed elsewhere in the labeling:

• Changes in Menstrual Bleeding Patterns [see WARNINGS AND PRECAUTIONS]
• Ectopic Pregnancies [see WARNINGS AND PRECAUTIONS]
• Thrombotic and Other Vascular Events [see WARNINGS AND PRECAUTIONS]
• Liver Disease [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In clinical trials including 942 women who were evaluated for safety, change in menstrual bleeding patterns (irregular menses) was the most common adverse reaction causing discontinuation of use of IMPLANON (11.1% of women).

Adverse reactions that resulted in a rate of discontinuation of ≥ 1% are shown in Table 3.

Table 3: Adverse Reactions Leading to Discontinuation of Treatment in 1% or More of Subjects in Clinical Trials of IMPLANON

Other adverse reactions that were reported by at least 5% of subjects in clinical trials of IMPLANON are listed in Table 4.

Table 4: Common Adverse Reactions Reported by ≥ 5% of Subjects in Clinical Trials with IMPLANON

Implant site complications were reported by 3.6% of subjects during any of the assessments in clinical trials. Pain was the most frequent implant site complication, reported during and/or after insertion, occurring in 2.9% of subjects. Additionally, hematoma, redness, and swelling were reported by 0.1%, 0.3%, and 0.3% of patients, respectively [see WARNINGS AND PRECAUTIONS].

Postmarketing Experience

The following additional adverse reactions have been identified during post-approval use of IMPLANON. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Gastrointestinal disorders: constipation, diarrhea, flatulence, vomiting.

General disorders and administration site conditions: edema, fatigue, implant site reaction, pyrexia.

Infections and infestations: rhinitis, urinary tract infection.

Investigations: clinically relevant rise in blood pressure, weight decreased.

Metabolism and nutrition disorders: increased appetite.

Musculoskeletal and connective tissue disorders: arthralgia, musculoskeletal pain, myalgia.

Nervous system disorders: convulsions, migraine, somnolence.

Pregnancy, puerperium and perinatal conditions: ectopic pregnancy.

Psychiatric disorders: anxiety, insomnia, libido decreased.

Renal and urinary disorders: dysuria.

Reproductive system and breast disorders: breast discharge, breast enlargement, ovarian cyst, pruritus genital, vulvovaginal discomfort.

Skin and subcutaneous tissue disorders: (aggravation of) angioedema and/or aggravation of hereditary angioedema, alopecia, chloasma, hypertrichosis, pruritus, rash, seborrhea, urticaria.

Vascular disorders: hot flush.

Complications related to insertion or removal of the implant reported include: bruising, slight local irritation, pain or itching, fibrosis at the implant site, paresthesia or paresthesia-like events, scarring and abscess.

Read the Implanon (etonogestrel implant) Side Effects Center for a complete guide to possible side effects »

Changes in Contraceptive Effectiveness Associated with Coadministration of Other Products

Drugs or herbal products that induce enzymes, including CYP3A4, that metabolize progestins may decrease the plasma concentrations of progestins, and may decrease the effectiveness of IMPLANON. In women on long-term treatment with hepatic enzyme inducing drugs, it is recommended to remove the implant and to advise a contraceptive method that is unaffected by the interacting drug.

Some of these drugs or herbal products that induce enzymes, including CYP3A4, include:

• barbiturates
• bosentan
• carbamazepine
• felbamate
• griseofulvin
• oxcarbazepine
• phenytoin
• rifampin
• St. John's wort
• Topiramate

HIV Antiretrovirals

Significant changes (increase or decrease) in the plasma levels of progestin have been noted in some cases of co­administration with HIV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors. Consult the labeling of all concurrently-used drugs to obtain further information about interactions with hormonal contraceptives or the potential for enzyme alterations.

Increase in Plasma Concentrations of Etonogestrel Associated with Coadministered Drugs

CYP3A4 inhibitors such as itraconazole or ketoconazole may increase plasma concentrations of etonogestrel.

Changes in Plasma Concentrations of Coadministered Drugs

Hormonal contraceptives may affect the metabolism of other drugs. Consequently, plasma concentrations may either increase (for example, cyclosporin) or decrease (for example, lamotrigine). Consult the labeling of all concurrently-used drugs to obtain further information about interactions with hormonal contraceptives or the potential for enzyme alterations.

Last reviewed on RxList: 2/28/2012
This monograph has been modified to include the generic and brand name in many instances.