The following advice applies to both Nexplanon^® and Implanon^® [FSRH, 2010d].

• Advantages:
• The implant is very effective: over 3 years, fewer than 1 in 1000 women will become pregnant:
• No pregnancies have been reported in clinical trials, but pregnancies have occasionally occurred in practice, usually because of operator error or method failure [National Collaborating Centre for Women's and Children's Health, 2005].
• Users do not have to think about contraception for 3 years.
• Sex need not be interrupted to use contraception.
• Can be used when breastfeeding.
• Normal fertility returns as soon as the implant is removed.
• Can be used in women in whom combined oral contraceptives (and other medicines with oestrogens) are not recommended, such as migraine without aura or history of migraine with aura.
• May reduce the risk of endometrial cancer.
• Not associated with any serious adverse effects. There is evidence that contraceptive implants have no adverse effects on [National Collaborating Centre for Women's and Children's Health, 2005]:
• Blood pressure.
• Venous thromboembolism.
• Risk factors for cardiovascular disease.
• Bone mineral density.
• Diabetes.
• Effective in women of all weights [National Collaborating Centre for Women's and Children's Health, 2005].
• However, the manufacturer advises earlier replacement of the implant in 'heavier women' [ABPI Medicines Compendium, 2006].
• Disadvantages:
• Most women will have changes in menstrual bleeding, and bleeding patterns are likely to remain irregular [National Collaborating Centre for Women's and Children's Health, 2005]:
• 20% of women will have no bleeding, and almost 50% of women will have infrequent, frequent, or prolonged bleeding.
• Bleeding problems result in almost 33% of women having their implant removed within 2 years.
• Irregular bleeding associated with implant-use can be treated with mefenamic acid or ethinylestradiol.
• Acne may develop (but it may also improve) in some women [National Collaborating Centre for Women's and Children's Health, 2005].
• Contraceptive efficacy likely to be reduced in women using liver enzyme–inducing drugs [FFPRHC, 2006a].
• An implant does not protect against sexually transmitted infections.
• Fitting and removing the implant requires a minor surgical procedure and may cause some pain, bruising, itching, or irritation.
• The surgical procedure can rarely (less than 1 in 100 women) cause such problems as an abscess, scarring, and migration or expulsion of the implant [National Collaborating Centre for Women's and Children's Health, 2005].
• Changes in weight, mood, libido, or headaches are commonly reported by women using progestogen-only implants. However, research has not shown that these problems, which are common in the general population, are associated with the implant [National Collaborating Centre for Women's and Children's Health, 2005].
• Other problems cause about 6% of women to have their implant removed within 2 years [National Collaborating Centre for Women's and Children's Health, 2005].
• Risks:
• No association with any serious adverse effects. In particular:
• There is no evidence that the risk of acquiring a sexually transmitted infection (including HIV) is increased.
• There is no evidence of a teratogenic effect; however, if a woman becomes pregnant and continues with the pregnancy, the implant should be removed [National Collaborating Centre for Women's and Children's Health, 2005].