Contraception – Hormonal Implants
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The hormonal implant (aka Implanon after a commonly used brand) is a form of contraception that involves placing a rod-shaped device subcutaneously, typically in the skin of the upper arm, which then slowly releases progesterone, providing effective contraception for 3 years.


  • Efficacy:
    • 99.5% effective
    • 1 woman in 200 will get pregnant in the course of a year when used as the sole form of contraception
  • LARC – long-acting reversible contraception
    • LARC methods tend to be more effective (‘set and forget’) than other methods (e.g. pill or condoms)
  • Lasts up to 3 years
  • Simple procedure to insert and remove with local anaesthetic
  • Does not effect bone density (unlike injectable progesterone)
  • Quick to reverse when removed


  • Unpredictable bleeding patterns – 20% will have amenorrhoea, 60% have irregular periods, 20% will have frequent or prolonged bleeding – most of these will improve within 3 months. This can be alleviated with:
    • Tranexamic acid – 1g/6-8h for up to 5 days – an antifibrinolytic, can reduce menorrhagia by 50%
    • Mefanamic acid – 500mg/8h – an NSAIDantiprostaglandin – taken during periods of heavy bleeding, can reduce menorrhagia by 30%. Is also useful for dysmenorrhoea. Contraindicated in peptic ulcer disease
    • Other NSAIDs may also be beneficial
    • Removal of the implant
    • Use of the COCP for 3 months in conjunction with the implant
  • Additional training required by practitioner for insertion and removal – can restrict access to the method
  • Breast tenderness, headache, mood changes


Quoted as: >99% effective
Described as: over the three year duration of treatment, <0.1% of women will become pregnant

  • In obese women, the level of etongestrel (the active ingredient) is reduced during the third year, and there may be a risk of pregnancythus replacement or alternative contraception should be sought after 2 years


  • Progesterone released slowly
  • Prevents ovulation
  • Thickens cervical mucous
  • Prevents proliferation of the endometrium, making implantation difficult.

Side effects

  • Acne
  • Breast tenderness
  • Mood swings
  • Changes in libido
  • Infection
    • Small risk of local infection at the implant site
  • Affect on periods – can make them shorter, longer, heavier or lighter, and the response is unpredictable. If bleeding is particularly heavy or persistent, it can be treated with…

Benefits over oral POP

More likely to inhibit ovulation, thus:

  • Less likelyhood of periods
  • Recued risk of ovarian cysts and ectopic pregnancy

Also, no interaction with non-enzyme inducing antibacterials

Prescribing and Administration

Can be fitted at any point during the menstrual cycle

  • If fitted in the first 5 days is immediately effective
  • If fitted at any other time, another form of contraception (e.g. condoms) will need to be used for the first 7 days after implanting

Fitting the implant

  • Fitted on the medical aspect of the upper arm
  • Goes just under the skin (subcutaneous)
  • Local anaesthetic given to numb the area
  • Feels similar to an injection
  • Area may be sore for 2-3 days after. The implant can be felt under the skin
Omplanon insertion device
Example of an Implanon insertion device. Note that the device itself is within the needle to facilitate an easy insertion. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Implanon insertion device
Another example of a more modern Implanon insertion device

Removing the implant

  • Can be removed at any time, should be removed after 3 years
  • Normally done in clinic by a GP
  • Local anaesthetic used, a small incision is made, and the implant removed
  • In some patients, the implant may be difficult to feel, and these patients will need to be referred to have it removed via guided USS.
  • If the patient intends to carry on using implants as contraception, a further implant can be fitted at the same time as the old one is removed.
  • After permanent removal – fertility returns quickly. Advise the patient pregnancy can occur before periods have returned to normal.
Implanon during removal.
Implanon during removal – note the small incision and the tip of the device poking through the incision. At this point, the device should be grabbed (usually with forceps) and is typically easily removed. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Implanon after removal
Implanon after removal. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

After pregnancy

  • Can be fitted on or before day 21 after to birth to provide immediate protection
  • If fitted after 21 days, additional contraception (e.g. condoms) will have to be used for 7 days

After abortion / miscarriage

  • Can be fitted immediately for immediate protection

Drug Interactions

Enzyme inducting drugs

  • E.g. St John’s Wort
  • TB, epilepsy and HIV medications
  • If the patient also takes any of these, it is recommended to use additional contraception (e.g. condoms) for the duration of the treatment and for 4 weeks after

Unlike some other forms of contraception, the implant is not affected by diarrhoea, vomiting or antibiotics.


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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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