Contraceptive Implant: How It Works and What to Expect

✓ This content has been medically reviewed by an obstetrician and gynaecologist
Written & medically reviewed by: Op. Dr. Ayşet Jane Özcan, Obstetrics & Gynaecology Specialist
Istanbul Faculty of Medicine · Medical Park Bahçelievler · TJOD and TSRM member
Last updated: 24 October 2026 · Last medical review: 24 October 2026

The contraceptive implant is a small, soft plastic rod, roughly the size of a matchstick, that sits just under the skin of your inner upper arm and slowly releases a progestogen hormone. Once it is in place there is nothing to take, nothing to remember and nothing to do until it is due to be changed or you decide you want it out. That is the whole appeal of it, and it is why the implant is grouped with the coil as long-acting reversible contraception.

It is also a method people tend to have strong feelings about, usually because of one thing: what it does to bleeding. I want to set that expectation honestly rather than leave you to discover it. Below I go through what the implant is, exactly how it is fitted and removed, whether it hurts, how long it lasts, the bleeding patterns you may get and which of them settle, the other side effects worth knowing about, who it suits and who it does not, how quickly fertility returns afterwards, and how it compares with the coil, the injection and the pill.

What the contraceptive implant is

The implant is a single flexible rod about 4 cm long and 2 mm wide, placed in the fatty layer directly under the skin of the inner upper arm, usually the arm you do not write with. It contains a progestogen called etonogestrel, which is released at a slow, steady rate for the whole time the implant is in place. It contains no oestrogen at all, which is one of the main reasons it is an option for people who cannot use the combined pill, patch or ring.

It sits under the skin, not in muscle and not in a blood vessel. In most people it is not visible, but it should be possible to feel it as a firm line if you run a fingertip over the area. It also contains a small amount of barium, which means it shows up on an X-ray if it ever needs to be located. People call it the arm birth control implant, the rod, or simply the implant, and in clinic notes you will often see it written as a subdermal implant.

Why it is called long-acting reversible contraception

Long-acting means that one short appointment covers you for years rather than days. Reversible means exactly that: it can be taken out whenever you want, and the hormone leaves your body within days of removal. That is the key difference between the implant and sterilisation. You do not need a reason to have it removed and you do not need to justify changing your mind.

• It is one single rod, not several pellets or a cluster of rods.
• It does not travel around the body; it stays in the arm where it was placed.
• It contains no oestrogen, so the oestrogen-related cautions do not apply to it.
• It gives no protection whatsoever against sexually transmitted infections.
• It can be removed at any point, including the week after it was fitted.

How the implant prevents pregnancy, and how reliable it is

The implant works mainly by preventing ovulation. A steady background level of progestogen suppresses the hormonal surge from the pituitary gland that would normally release an egg each month, so in most cycles no egg is released at all. On top of that, it thickens the mucus at the neck of the womb, making it harder for sperm to get through, and keeps the lining of the womb thin.

The reason the hormone level matters so much is that the implant releases it continuously. There is no daily peak and trough the way there is with a tablet, and no window in which the level drops low enough for an egg to escape. That steadiness is also why the dose can be so low compared with older progestogen methods.

How reliable it is

I am not going to quote you a figure, because figures get repeated out of context. What matters practically is this: the implant sits in the most reliable group of contraceptive methods available, alongside the intrauterine device. Pregnancy while a correctly placed, in-date implant is in the arm is uncommon.

The reason is simple and worth understanding, because it is the real argument for this method. With the pill, how well it works depends on you taking it at roughly the same time every day, on not vomiting an hour after it, and on not running out of packets on holiday. With the implant, none of that applies. There is no user error to make. The gap between perfect use and real life, which is where most unplanned pregnancies come from, essentially closes.

There is one genuine exception, and it is important. Certain medicines speed up the liver enzymes that break the hormone down, which lowers the blood level enough to matter. The implant is unusual among long-acting methods in being affected this way; a copper or hormonal coil is not. I cover which medicines these are below. Ordinary antibiotics for a chest infection or urine infection are not among them and do not stop the implant working.

Hormone levels do fall slowly across the life of the implant, and there has been long-running discussion about whether higher body weight lowers them further. Current guidance does not routinely recommend changing the implant early for this reason, but it is a fair question to raise at your appointment rather than wonder about silently.

How the implant is fitted, and does it hurt

Having the implant fitted is a short outpatient procedure done under local anaesthetic, and the sting of the local anaesthetic is usually the only part that actually hurts. The insertion itself takes about a minute. The whole appointment, including the conversation beforehand and the dressing afterwards, is normally fifteen to twenty minutes.

What happens step by step

First there is a consultation: your medical history, any medicines or herbal remedies you take, your bleeding pattern, and a check that you are not already pregnant. No blood tests or scans are needed for this method.

Then you lie on your back with the chosen arm bent at the elbow and your hand up near your head. The site is marked on the inner upper arm, roughly eight to ten centimetres above the bony point on the inside of the elbow, and about three to five centimetres behind the groove between the biceps and triceps - over the back of the arm rather than in the groove itself, which is where the main nerves and blood vessels run. That position is chosen to keep well away from those nerves and vessels.

The skin is cleaned and a small amount of local anaesthetic is injected under it. This stings for a few seconds and then the area goes numb. The implant comes pre-loaded in a single-use applicator, so there is no cut: the needle of the applicator is slid just under the skin, almost parallel to it, and the rod is left behind as the needle is withdrawn.

Your clinician will then feel both ends of the implant through your skin, and should ask you to feel it too. Do take that moment seriously. Knowing where your implant is, and being able to find it yourself, makes removal in three years straightforward and means you will notice quickly if anything changes.

Finally a small dressing goes on, with a firm pressure bandage over the top to reduce bruising.

Does it hurt, honestly

The local anaesthetic stings briefly. After that, most people describe pressure or a pushing sensation rather than pain, and many are surprised how quickly it is over. Afterwards the arm is commonly tender for a few days and bruised for one to two weeks. The bruise can look dramatic and spread down the arm with gravity; that is not a sign that something went wrong.

• Bring a list of all your medicines, including anything herbal such as St John's wort.
• Say which hand you write with, so the implant goes in the other arm.
• Mention any previous problem with local anaesthetic.
• Mention if you bruise very easily or take a blood thinner.
• Write down the date it was fitted, or photograph the card you are given.

Looking after your arm in the first week

• Keep the pressure bandage on for about twenty-four hours, then remove it.
• Keep the small dressing underneath clean and dry for three to five days.
• Expect tenderness and bruising; simple over-the-counter painkillers are enough if you need them.
• Once the dressing is off, check that you can feel the implant yourself.
• Avoid heavy lifting or sustained pressure on that arm for the first day or two.

When the implant starts working

Whether you are protected immediately depends on when in your cycle the implant goes in. If it is fitted within the first five days of your period, you are covered straight away and need nothing extra. If it is fitted at any other point in the cycle, you need condoms, or to avoid sex, for the following seven days while the hormone level builds.

The logic behind those two rules is worth a sentence, because it makes them easier to remember rather than easier to get wrong. In the first few days of a period, no egg has yet begun to mature, so suppressing ovulation from that point is enough on its own. Later in the cycle, an egg may already be on its way, and the implant needs roughly a week of steady hormone before it can be relied on to hold things back.

If you have had sex without contraception in the days before your appointment, say so plainly rather than hoping the implant will cover it retrospectively. It will not. A pregnancy test is done first, emergency contraception may need to be considered, and depending on what is used your clinician may advise either fitting the implant that day with extra precautions and a repeat test, or coming back. None of that is a reason to cancel the appointment; it just needs saying out loud.

Switching from another method, and other timings

The implant can be fitted after childbirth, including while you are breastfeeding, and after a miscarriage or abortion, often at the same appointment. If you are switching from the pill, patch, ring, injection or a coil, the overlap rules differ depending on what you were using, how consistently you used it, and where you are in the packet or the injection interval. Sometimes no extra cover is needed at all; sometimes you are asked to keep taking the old method for a few days, or to use condoms for a week.

Because those rules genuinely vary, the only sensible approach is to ask specifically, at the appointment, what applies to you and for how many days, and to write the answer down rather than relying on memory on the way home. If a coil is being removed at the same visit, ask too about whether you need to avoid sex in the days beforehand, which is a detail people are commonly not told.

One more practical point: nothing about the implant protects against sexually transmitted infections, at any point in the cycle. If that is a possibility for you, condoms stay part of the picture permanently, not just for the first seven days.

How long the contraceptive implant lasts

In the UK the implant is licensed for three years, and licensed duration can differ between countries, so check what applies where your implant was fitted. At the end of that time it is removed, and if you want to carry on with the method a new one is fitted, usually at the same appointment and often through the same tiny incision. You do not have to wait three years: it can come out at any point before that, for any reason.

Protection does not stop abruptly on the anniversary, but you should not rely on it beyond its licensed life unless your own clinician has specifically advised otherwise for your situation. This is where the date matters. Put a reminder somewhere you will actually see it, three years ahead, and add a second reminder a couple of months earlier so you have time to book.

If you genuinely do not know when yours was fitted, or you have moved country or changed clinic and the records are gone, do not simply assume it is still working. Get it reviewed, and use condoms in the meantime. The same applies if you are approaching the end of its licensed life and cannot get an appointment immediately.

Bleeding pattern changes: what to actually expect

Almost everyone's bleeding pattern changes on the implant, and the change is unpredictable. This is the single most common reason people decide to stop using it. It is not dangerous and it does not mean anything is going wrong, but it can be genuinely inconvenient, and you are better off deciding in advance how much unpredictability you are prepared to live with than discovering it in month two.

The patterns you may get

• No bleeding at all. Common, and safe. The lining of the womb stays thin, so nothing is building up inside waiting to come out.
• Lighter, shorter or less frequent bleeds than you used to have.
• Frequent light spotting that comes and goes with no obvious pattern.
• Prolonged bleeding: light bleeding or spotting that drags on for days or a couple of weeks.
• Less commonly, bleeding that is heavier than your usual period.

The first three to six months are the most unsettled. For many people the pattern quietens down after that and either settles into something infrequent or stops altogether. But a proportion of people continue to have irregular spotting for as long as the implant is in, and there is no test and no feature of your history that reliably predicts in advance which group you will be in. Anyone who tells you otherwise is guessing.

Irregular bleeding is not automatically the implant

Before accepting troublesome bleeding as a side effect, it is worth excluding other causes, particularly if the bleeding starts after months of a settled pattern. That means a pregnancy test, testing for chlamydia and other infection where relevant, checking your cervical screening is up to date, and considering fibroids or polyps. Bleeding that comes with pelvic pain, abnormal discharge or bleeding after sex needs looking into rather than attributing to the rod in your arm. The same reasoning applies to irregular periods from any cause: the method you are using is one explanation among several, not the default one.

What can be done about it

If nothing else is found, there are three broad routes. The first is to wait, because many patterns improve with time. The second is a limited course of additional treatment to settle the bleeding: options include taking a combined hormonal preparation alongside the implant for a short period if you are medically suitable for oestrogen, or an anti-inflammatory medicine taken during bleeding episodes. Which, and for how long, is an individual decision to make with your own clinician, so I am not going to put doses on a web page. The third route is to have the implant removed and change method.

My usual advice is not to abandon the implant in the first few weeks unless the bleeding is heavy or really distressing. Give it a fair run of three to six months. Equally, if you have given it six honest months and the bleeding is still ruling your life, that is a perfectly good reason to stop, and you do not have to keep going to prove something.

Other side effects, and what tends to settle

Beyond bleeding, the side effects of the implant are hormonal, usually mild, and often settle within the first few months as your body adjusts. These are the ones patients ask about most.

Skin and acne

Acne can appear or get worse on the implant, and in some people it improves. Progestogen-only methods do not contain the oestrogen that helps acne in the combined pill, which is why skin is a more common complaint here. For most people it is manageable with ordinary skin care; if it becomes severe and persistent, it is a reasonable reason to reconsider the method.

Headaches and breast tenderness

Both are common in the first few months and usually fade. Breast tenderness in that early window is nearly always hormonal, but do not let the implant become an explanation for everything: a new discrete lump, persistent one-sided pain or any nipple discharge should be examined rather than assumed, and the usual approach to working out what is causing breast pain still applies.

Mood

Some people report feeling flat, low or more irritable on the implant. Studies across large populations have not shown a consistent effect on mood, but population averages are not much comfort if it is happening to you. If your mood clearly changed after the implant was fitted and has stayed changed, that is a legitimate reason to have it removed, and you should say so plainly rather than wait to be asked. If mood changes are severe, or you have any thoughts of harming yourself, seek help the same day rather than at your next routine appointment.

Weight

There is no consistent evidence that the implant causes meaningful weight gain. Some people notice appetite changes. It is also true that weight drifts over three years for all sorts of reasons that have nothing to do with contraception, which makes it very easy to attribute a change to the implant after the fact. If this matters to you, note your weight at the time of fitting so you have something real to compare with later.

Ovarian cysts

Because ovulation is interrupted part-way through, follicles in the ovary can keep growing and persist for a while. On a scan these look like simple fluid-filled cysts. They are usually harmless, resolve on their own and need no treatment, though occasionally they cause brief one-sided pelvic discomfort.

The arm itself

Bruising and tenderness are expected. You will be left with a very small scar at the insertion site. Infection at the site is uncommon and treatable. The main technical problem is an implant placed deeper than intended, which makes later removal more difficult; very rarely, insertion that is too deep can injure a nerve or vessel in the arm. The implant may feel as though it has shifted slightly from where it started, which is usually of no consequence; movement out of the arm altogether is very rare.

Who the implant suits, and who it does not

In short: the implant suits people who want highly reliable contraception without a daily routine and who can accept an unpredictable bleeding pattern. It does not suit people who need predictable periods, or who have particular medical conditions or take particular medicines. Deciding which group you are in is most of the consultation, and it is the sort of thing worth raising at a general women's health review rather than in a rushed five minutes.

It often suits you if

• You want contraception you do not have to think about day to day.
• You cannot use oestrogen, or would rather avoid it: migraine with aura, a previous blood clot, high blood pressure, or smoking over the age of 35.
• You are breastfeeding; the implant is compatible with breastfeeding.
• A coil is not acceptable to you, or an internal examination is difficult or distressing, for example with vaginismus or after a previous bad experience.
• You have a medical condition that makes pregnancy risky and you want something dependable.
• You might want to try for pregnancy in the next year or two and want a method you can stop quickly.
• You have struggled to take a pill consistently, for any reason at all. That is information, not a failing.

It is not the right choice if

• You have breast cancer now or have had it recently; progestogen methods are generally avoided and this needs to be discussed with your oncology team.
• You have unexplained vaginal bleeding that has not yet been investigated. Find the cause first, then choose contraception.
• You have severe active liver disease.
• You take an enzyme-inducing medicine. The usual ones are some anti-epileptic drugs such as carbamazepine, phenytoin and primidone, the antibiotics rifampicin and rifabutin, certain HIV medicines, and the herbal remedy St John's wort. These lower the hormone level, and a coil or the injection is usually preferred instead.
• You might already be pregnant.
• You need predictable, countable periods, whether for personal, religious or practical reasons. This is a real and valid reason to choose something else.
• You need protection from sexually transmitted infections. Nothing about the implant provides that, so condoms are still needed.

Age is not in itself a barrier at either end of reproductive life, and never having been pregnant is not a barrier either. Having had the implant before and disliked it is, reasonably, a good argument against trying it again.

How the implant is removed

Removal is a short procedure under local anaesthetic through an incision of two to three millimetres, and it usually takes a few minutes. Most people find it comparable to insertion or easier, partly because they know what to expect.

Your arm is positioned the same way as for insertion. Your clinician feels for both ends of the implant, injects local anaesthetic underneath the end nearest your elbow, and makes a tiny cut there. The implant is then pushed gently towards the cut and lifted out with forceps. Sometimes a thin layer of tissue has formed around the tip and needs to be opened first, which adds a minute. The cut is closed with an adhesive strip or small dressing, occasionally a single stitch, and a pressure bandage goes on again to limit bruising. The resulting scar is small.

If you want to continue with the method, a new implant can usually be inserted through the same incision at the same visit, so it is one appointment rather than two.

If the implant cannot be felt

Occasionally an implant cannot be felt clearly, most often because it was placed deeper than intended. This is not an emergency, but it does mean two things: do not rely on it for contraception until its position and timing are confirmed, and do not let anyone go hunting for it blindly. The correct next step is imaging, with a high-frequency ultrasound probe or an X-ray, since the implant contains barium and is visible on film. Occasionally an MRI is used. Removal is then arranged with someone who has specific experience of difficult removals, sometimes in a hospital setting. This is precisely why careful insertion technique, and your own ability to feel your implant, matter.

Reasons to have it removed

Whenever you want is a complete answer. The common specific reasons are: bleeding you are not willing to continue with, side effects that have not settled, reaching the end of its licensed life, wanting to try for a pregnancy, or a new medical diagnosis that makes a progestogen less suitable.

Return to fertility after the implant is removed

Fertility returns quickly after the implant is removed. The hormone clears from the blood within a few days, and ovulation usually resumes within a few weeks. There is no washout period, no need to wait a given number of cycles before trying, and no evidence that the implant affects long-term fertility, however many years you used it for.

That has two practical consequences, pulling in opposite directions.

If you do not want to be pregnant, you need another method starting the day the implant comes out, not the following week. Pregnancy is possible before your first period returns, and people are caught out by this surprisingly often. Plan the next method before the removal appointment, not after it.

If you do want to conceive, you can start trying immediately. Many people ovulate in the first cycle after removal, and the usual signs that you are ovulating become useful again once the implant is out. Your own cycle pattern may take two or three months to reassert itself, particularly if you had no bleeding at all while the implant was in. That settling-in period is the cycle re-establishing itself, not a problem to be treated.

Two situations deserve a review rather than patience. If your periods have not returned at all within about three months of removal, have it looked into. And if you have been trying for a year without conceiving, or six months if you are over 35, start the usual fertility assessment rather than continuing to blame the implant, which by then is not the explanation.

If pregnancy is the plan, the standard pre-conception advice applies from the moment the implant is out: folic acid, a review of any long-term medicines for suitability in pregnancy, and making sure your rubella and other vaccinations are in order.

Implant, coil, injection or pill: how the choice is made

The choice between the implant, a coil, the injection and the pill usually comes down to four practical questions: how much you want to think about contraception day to day, what you want your bleeding to do, whether a pelvic procedure is acceptable to you, and how soon you might want to be pregnant. Effectiveness is rarely the deciding factor between the long-acting methods, because they are all in the dependable group.

Implant or coil

Both are fit-and-forget. The difference is the location, the bleeding and the procedure. A coil goes into the womb and lasts longer per device. A hormonal coil usually makes periods lighter and is often considered first when heavy or painful periods are the main problem, while a copper coil is hormone-free but typically makes periods heavier and more crampy. Fitting a coil involves an internal examination and passing a device through the cervix, which some people find difficult or unacceptable. Coils are also unaffected by enzyme-inducing medicines. The implant avoids any pelvic procedure altogether, but gives you less predictable bleeding. If you are weighing these two seriously, read the detail on how coils are fitted, how they feel and how they differ before your appointment.

Implant or the injection

The injection is given every eight to thirteen weeks depending on the type. The crucial practical difference is that once an injection is given it cannot be taken back out: if it does not agree with you, you have to wait for it to wear off, whereas an implant can be removed this week. Return of fertility after stopping the injection can also be delayed by several months, and long-term use is discussed in terms of its effect on bone density. The implant has neither of those issues, which is why it is often preferred for people who want a long-acting method but are not certain they will get on with it.

Implant or the pill

The pill keeps you in control day to day and can be stopped without a procedure, which some people value a great deal. A combined pill usually gives predictable, often lighter and less painful bleeding, and can help acne, but it contains oestrogen and so is not suitable for everyone. The progestogen-only pill has a bleeding profile much like the implant's, with the added requirement of taking it on time every day. The honest question to ask yourself is not whether you could remember a daily pill in principle, but whether you have actually managed it before.

What usually tips the decision

• Heavy or painful periods as the main complaint: a hormonal coil is often considered first.
• No pelvic procedure, under any circumstances: the implant.
• Enzyme-inducing medicines: a coil, or the injection.
• A predictable cycle you can plan around: a combined hormonal method.
• Possible pregnancy within the year: the implant or the pill, both of which stop quickly.
• Any risk of sexually transmitted infection: condoms as well, whichever method you choose.

And it is worth saying clearly: choosing a method is not a commitment to it. If it does not suit you, you change it. That is a normal part of contraceptive care, not a failure of the decision you made last year.

When to seek medical advice

Most things that happen after an implant is fitted are bruising and unpredictable spotting, and both are expected. The following are not, and should be assessed rather than waited out.

Your arm

• Spreading redness, increasing pain, warmth, swelling or any discharge at the site, especially with a temperature. This suggests infection and needs same-day review.
• You cannot feel the implant, or you can feel only one end. Use condoms and get it checked.
• The implant feels as though it is poking out, or the skin over it is breaking down.
• Numbness, pins and needles, or weakness in that arm or hand.

Bleeding and pain

• Bleeding heavy enough to soak through protection every hour, or bleeding with dizziness, breathlessness or fainting.
• New bleeding after months of a settled pattern, particularly with pelvic pain, abnormal discharge or bleeding after sex.
• Severe one-sided lower abdominal pain, with or without pain at the tip of the shoulder, feeling faint or collapsing. Pregnancy with an implant in place is uncommon, but when it does happen an ectopic pregnancy has to be excluded, and the early warning signs of an ectopic pregnancy are worth knowing whatever contraception you use. This is an emergency, not a next-week appointment.
• Pregnancy symptoms such as nausea, breast changes or unusual tiredness. Do a test; any positive test with an implant in place needs prompt assessment.

Other reasons to be seen

• A new lump in the breast or armpit.
• Yellowing of the eyes or skin, or severe pain in the upper abdomen.
• A severe headache unlike your usual ones, or visual aura with a migraine for the first time.
• Low mood that is affecting your daily life, or any thoughts of harming yourself. Ask for help the same day.

None of this is meant to make a straightforward method sound alarming. The implant is a well-established, low-maintenance form of contraception that a great many people use without difficulty for years. But it is a method whose main drawback, unpredictable bleeding, is best discussed before it happens rather than afterwards. Bring your questions, your medicine list and your own priorities to the appointment, and the decision usually makes itself.