The contraceptive implant is a small, flexible rod placed under the skin of the upper arm that steadily releases progestogen to prevent pregnancy. It's more than 99% effective, lasts up to about 3 years, and — like the IUD — needs nothing to remember day to day. The most common side effect is a change in bleeding pattern.
How it works
According to the NHS and ACOG, the implant releases a steady low dose of progestogen, which:
- Stops ovulation (no egg is released),
- Thickens cervical mucus so sperm can't get through, and
- Thins the lining of the uterus.
It's a long-acting reversible contraceptive (LARC) — the same category as the IUD — meaning it works for years with no daily effort.
One underrated advantage follows from where it sits: because the hormone is absorbed through the skin rather than the gut, the NHS notes the implant keeps working normally even if you vomit or have diarrhoea, which is not true of the pill.
How effective is it?
The implant is over 99% effective. Because there's no daily pill to miss or per-act step, its real-world (typical-use) effectiveness matches perfect use — one of the reasons LARCs outperform the pill day to day. See the full methods comparison.
Protection doesn't necessarily start the moment it's fitted. The NHS explains that if the implant is inserted during the first five days of your menstrual cycle, you're protected straight away; at any other point in the cycle you need additional contraception, such as condoms, for seven days.
What to expect at the appointment
Insertion is a short outpatient procedure, and knowing the sequence takes most of the anxiety out of it.
- Before: a provider checks your medical history and medicines, and confirms you're not pregnant. You'll usually be asked which arm you use less — the implant goes in the non-dominant upper arm.
- Numbing: a small area of the inner upper arm is numbed with local anaesthetic. This is the part most people describe as a brief sting.
- Insertion: the rod is placed just under the skin with an applicator. It takes only a few minutes, and no stitches are needed.
- After: the arm is covered with a dressing and often a pressure bandage for the first day. Bruising, tenderness, or swelling for a few days is normal.
- Learn to feel it: you should be able to feel the rod under the skin. Being shown how at the appointment means you can check it yourself later.
Removal is a similarly short procedure under local anaesthetic, through a tiny incision. You can ask for it at any time, for any reason.
Side effects
The most common change is to your bleeding pattern:
- Periods may become irregular, lighter, or stop altogether.
- Some people have more frequent or prolonged bleeding, especially in the first months.
Bleeding changes are not a sign that something is wrong, and periods stopping is not harmful. They are, however, the most common reason people ask for early removal — so it's worth deciding in advance how you'd feel about an unpredictable pattern. If irregular bleeding persists beyond the first few months, a provider can discuss options, since it sometimes settles and sometimes doesn't.
Other common effects include headaches, acne (which can improve or worsen), breast tenderness, and mood changes — often settling within a few months. Less common issues include a small area of infection, bruising, or scarring at the insertion site.
Who it suits — and who it doesn't
The implant is a strong fit if you want top-tier effectiveness with no daily routine, you can't take estrogen, or you simply don't want to think about contraception for years at a time. It's progestogen-only, so it avoids estrogen-related risks, making it suitable for many people who can't take the combined pill, including many who are breastfeeding.
It's a weaker fit if:
- You want predictable periods. If a regular, expected bleed matters to you, the combined pill, patch or ring offer far more predictability.
- You take enzyme-inducing medicines. The NHS notes that some medicines — including certain epilepsy and tuberculosis treatments, and the herbal supplement St John's wort — can make the implant less effective, and additional contraception may be advised.
- You have certain medical conditions. The NHS lists unexplained bleeding between periods or after sex, some liver conditions, and a history of breast cancer among the reasons the implant may not be suitable.
- You're uncomfortable with a minor procedure. Insertion and removal are quick, but they are procedures, and some people prefer to avoid them.
Like most methods, the implant is not reliably linked to weight gain for most people — see does birth control cause weight gain.
How it compares to the alternatives
Against the hormonal IUD, the implant is easier to insert and remove and involves no pelvic procedure, but the IUD often lasts longer and is more likely to reduce heavy bleeding. Against the injection, the implant wins clearly on return to fertility: implant users typically conceive soon after removal, while the injection can take considerably longer to wear off. Against the pill, it removes the entire problem of daily timing, which is why its real-world effectiveness is so much higher.
Cost and access
Availability varies by country. In the UK, the NHS provides the implant free of charge at GP surgeries and sexual health clinics, though not every practice fits them, so you may be referred. In the United States, Planned Parenthood notes that most health insurance plans cover the implant, with reduced-cost options through community and publicly funded clinics. Because one appointment buys several years of protection, a LARC is often less expensive over time than a recurring supply of pills — worth factoring in if you're paying out of pocket.
What it doesn't do
The implant prevents pregnancy only — it offers no STI protection. Use condoms to reduce STI risk.
The bottom line
The implant is a "fit and forget" option: highly effective, long-lasting, estrogen-free, and quickly reversible. The main trade-off is unpredictable bleeding, particularly early on, and the practical hurdle of two short procedures. If a low-maintenance, top-tier-effective method appeals, it's worth discussing with a provider — and comparing against the other long-acting options in our contraception guide. This article is general education and is not a substitute for individualized medical advice.
