*5.6.1 Side-effects*

Contraceptive implants may cause changes in menstrual bleeding in the first several months to 1 year of use, including lighter bleeding, fewer days of bleeding, prolonged bleeding, irregular bleeding, and even no bleeding. After about 1 year of use, the pattern of bleeding becomes more regular. Changes in bleeding patterns as a result of implants are not harmful but are a common drawback of this contraceptive method. Amenorrhea occurs in approximately 20% of women in the first year of use, although this rates declines with duration of use to 13% by year 3 [113].

Unscheduled bleeding was reported as the reason for discontinuation of this method among 14.8% of users in the U.S. and Europe and 3.7% in Southeast Asia, Chile, and Russia [114]. About 90% of women who discontinued the implant experienced frequent or prolonged bleeding/spotting versus 22% of those who continued using the device [115].

Like other progestogen-only forms of contraception, other possible-side effects of contraceptive implants include headaches, abdominal pain, mood changes, nausea, breast tenderness, dizziness, acne (either improvement or exacerbation), weight change, and possibly enlarged ovarian follicles [78, 110].

### *5.6.2 Risks*

Complications are reported in 0.3–1% of implant insertions and 0.2–1.7% of removals [116]. Uncommon insertion/removal complications include infection, hematoma formation, and local irritation and rashes at the insertion site; these occur mostly within the first 2 months of insertion. Clinician training and experience, and the use of a stringent, aseptic technique reduces the incidence of such complications.

In addition, rare complications can occur, including expulsion of the implant (occurring within the first 4 months of insertion) and migration of the implants over time a short distance (<2 cm) from the site of insertion [78, 117]. Nerve injuries have also been reported with implants, including injury to the branches of the medial antebrachial cutaneous nerve during placement and the medial antebrachial cutaneous nerve [118, 119].
