Contraceptive Implant: Complete Guide to Effectiveness & Side Effects

What Is a Contraceptive Implant?

A contraceptive implant is a small, flexible plastic rod about 4 cm long and 2 mm wide (similar to a matchstick) that is inserted just under the skin of your upper arm. It continuously releases a progestogen hormone called etonogestrel to prevent pregnancy for up to 3-5 years. The most common brand is Nexplanon.

The contraceptive implant represents one of the most significant advances in modern birth control, offering women a highly effective, long-acting, and reversible method of pregnancy prevention. Unlike daily pills or monthly injections, the implant works continuously once inserted, requiring no ongoing attention or compliance from the user. This "fit and forget" approach has made implants increasingly popular worldwide, with millions of women choosing this method for its convenience and reliability.

The implant belongs to a category of birth control methods known as long-acting reversible contraceptives (LARCs), which also includes intrauterine devices (IUDs). These methods are recommended by major medical organizations, including the World Health Organization (WHO) and the American College of Obstetricians and Gynecologists (ACOG), as first-line contraceptive options due to their exceptional effectiveness and ease of use.

The current generation of contraceptive implants uses a single rod design, representing an improvement over earlier versions that used multiple rods. This single-rod design makes insertion and removal simpler and quicker, while maintaining excellent contraceptive efficacy. The implant is radiopaque, meaning it can be seen on X-ray imaging, which helps healthcare providers verify its location if needed.

How the implant differs from other contraceptives

Unlike combined hormonal contraceptives (such as the pill, patch, or ring) that contain both estrogen and progestogen, the implant contains only progestogen. This makes it suitable for women who cannot use estrogen due to medical conditions such as a history of blood clots, migraine with aura, or while breastfeeding. The steady hormone release from the implant also provides more consistent blood hormone levels compared to the daily fluctuations seen with oral pills.

The effectiveness of the implant is not affected by factors that can reduce the reliability of other methods. Vomiting, diarrhea, or forgetting doses – common issues with oral contraceptives – have no impact on the implant's ability to prevent pregnancy. Similarly, unlike the contraceptive injection, there is no grace period or timing concerns with the implant; it works continuously from the moment it starts until it is removed or expires.

How Does the Contraceptive Implant Work?

The contraceptive implant works through three main mechanisms: it stops ovulation (release of an egg), thickens cervical mucus to prevent sperm from reaching an egg, and thins the uterine lining. The primary mechanism is preventing ovulation, which it does in approximately 97-99% of menstrual cycles.

The contraceptive implant provides pregnancy protection through multiple complementary mechanisms, which together create an extremely effective barrier against conception. Understanding how these mechanisms work can help women feel more confident in their contraceptive choice and better understand any changes they might experience while using the implant.

The primary mechanism of action is the suppression of ovulation. The etonogestrel hormone released by the implant signals to the brain's pituitary gland to reduce the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones are normally responsible for stimulating the ovaries to develop and release an egg each month. By suppressing these hormones, the implant prevents ovulation from occurring in the vast majority of menstrual cycles – studies show ovulation is suppressed in 97-99% of cycles during the first two years of use.

The second mechanism involves changes to the cervical mucus. The progestogen in the implant causes the mucus at the entrance to the uterus (cervix) to become thicker and more viscous. This creates a physical and chemical barrier that makes it extremely difficult for sperm to travel through the cervix and reach an egg. Even on the rare occasions when ovulation might occur, this thickened cervical mucus provides an additional layer of protection against pregnancy.

The third mechanism relates to changes in the uterine lining (endometrium). The progestogen causes the endometrium to become thinner than it would be in a normal menstrual cycle. While the implant prevents pregnancy primarily by stopping ovulation, this thinning of the uterine lining provides yet another safeguard. These changes to the endometrium are also responsible for the alterations in menstrual bleeding patterns that many implant users experience.

Hormone release pattern

The implant releases etonogestrel at a controlled rate that varies slightly over time. In the first year, the release rate is approximately 60-70 micrograms per day. This gradually decreases to about 35-45 micrograms per day by the end of the first year, and continues to decline to approximately 25-30 micrograms per day by the end of the third year. Despite this decline, the hormone levels remain sufficient to maintain contraceptive effectiveness throughout the approved duration of use. Recent research suggests that effectiveness may extend beyond three years, with some studies indicating continued protection for up to five years.

How Effective Is the Contraceptive Implant?

The contraceptive implant is over 99.95% effective at preventing pregnancy, making it one of the most reliable forms of birth control available. This means fewer than 1 in 2,000 women using the implant will become pregnant in one year. Unlike pills, its effectiveness is not reduced by user error.

When discussing contraceptive effectiveness, it is important to understand the difference between "perfect use" and "typical use" effectiveness rates. For methods like the pill, these rates differ significantly because typical use accounts for human error – forgotten pills, incorrect timing, or drug interactions. The contraceptive implant, however, is unique in that its perfect use and typical use effectiveness rates are virtually identical, both exceeding 99.95%.

This exceptional reliability occurs because the implant removes the possibility of user error. Once inserted by a trained healthcare provider, the implant requires no action from the user to maintain its effectiveness. There are no pills to remember, no devices to insert before sex, and no appointments to keep for repeat injections. The implant simply works continuously, day and night, for up to 3-5 years.

To put this effectiveness rate in perspective, consider that among 2,000 women using the contraceptive implant for one year, fewer than one would be expected to become pregnant. Compare this to 90 pregnancies among 1,000 women using no contraception, 60-90 pregnancies among 1,000 women using the pill with typical use, or 180 pregnancies among 1,000 women using condoms with typical use. The implant's effectiveness is comparable to surgical sterilization, yet it is completely reversible.

Factors that might affect effectiveness

While the implant's effectiveness is exceptionally high, certain medications may potentially reduce its efficacy by increasing the rate at which the hormone is metabolized by the liver. These include some anti-epileptic medications (such as phenytoin, carbamazepine, and phenobarbital), rifampicin and rifabutin (antibiotics used primarily for tuberculosis), and the herbal supplement St. John's Wort. If you are taking any of these medications, discuss alternative contraceptive options with your healthcare provider.

Importantly, commonly prescribed antibiotics (such as amoxicillin, azithromycin, or ciprofloxacin) do NOT affect the implant's effectiveness. This is a common misconception that persists from outdated information about older contraceptive formulations.

How Is the Contraceptive Implant Inserted?

The contraceptive implant is inserted in a simple procedure that takes only 3-5 minutes. After applying local anesthetic to numb your upper arm, the healthcare provider uses a special applicator to place the implant just under the skin. Most women describe feeling only a small pinch and report minimal discomfort.

The insertion of a contraceptive implant is a straightforward outpatient procedure performed by trained healthcare providers. The entire process typically takes less than five minutes, with the actual insertion itself taking only seconds. Understanding what to expect can help reduce any anxiety about the procedure.

Before insertion, your healthcare provider will discuss your medical history, explain the procedure, and confirm that you understand how the implant works, its potential side effects, and how long it will remain effective. They will also determine the optimal timing for insertion based on your menstrual cycle and current contraceptive use.

The insertion procedure step by step

Step 1: Preparation. You will typically lie on your back with your non-dominant arm (usually the left arm if you are right-handed) bent at the elbow and positioned near your head. The inner side of your upper arm, about 8-10 cm from the elbow crease, is cleaned with an antiseptic solution.

Step 2: Local anesthesia. A small amount of local anesthetic is injected into the skin at the insertion site. This causes a brief stinging sensation that lasts only a few seconds. The area then becomes numb, ensuring you won't feel pain during the insertion.

Step 3: Insertion. Using a specially designed applicator (similar to a large injection device), the healthcare provider inserts the implant just beneath the skin. You may feel a sensation of pressure but should not feel pain. The applicator is designed to place the implant at the correct depth – deep enough to be under the skin but shallow enough to be easily felt and removed later.

Step 4: Verification. After insertion, both you and your healthcare provider will feel the implant under the skin to confirm it has been correctly positioned. You should be able to feel the rod as a small, firm line under the skin surface. The insertion site is covered with a small adhesive bandage, and a pressure bandage may be applied to minimize bruising.

After the insertion

After the procedure, it is normal to experience some bruising, tenderness, or swelling at the insertion site. These effects typically resolve within 1-2 weeks. To minimize bruising, keep the pressure bandage on for 24 hours and the adhesive bandage for 3-5 days. Avoid heavy lifting or strenuous arm activities for a few days after insertion.

Contact your healthcare provider if you notice signs of infection (increasing redness, warmth, pus, or fever), cannot feel the implant under your skin, or experience severe or worsening pain at the insertion site.

What Are the Side Effects of the Contraceptive Implant?

The most common side effect of the contraceptive implant is a change in menstrual bleeding patterns. About 1 in 5 women stop having periods entirely (amenorrhea), while others experience irregular, prolonged, or infrequent bleeding. Other possible side effects include headaches, acne, breast tenderness, mood changes, and weight changes. Most side effects improve over time.

Like all medications and medical devices, the contraceptive implant can cause side effects. However, many women experience minimal or no significant side effects, and for most users, the benefits of highly effective contraception outweigh any temporary discomfort. Understanding the range of possible side effects can help you make an informed decision and know what to expect.

Changes to menstrual bleeding

The most common and often most noticeable effect of the contraceptive implant is a change in menstrual bleeding patterns. This is a normal response to the continuous progestogen hormone and affects most implant users to varying degrees. The changes are not harmful to health, though they can be inconvenient for some women.

Possible bleeding patterns include:

• No periods (amenorrhea): Approximately 20% of women stop having periods entirely after one year of use. This is medically safe and does not affect future fertility.
• Infrequent bleeding: Some women have fewer periods than before, perhaps only every few months.
• Frequent or irregular bleeding: Especially in the first 6-12 months, some women experience irregular spotting or more frequent bleeding. This often improves with time.
• Prolonged bleeding: Some women have bleeding episodes that last longer than a typical period.
• Regular bleeding: A minority of women continue to have relatively regular monthly bleeding.

Research shows that bleeding patterns in the first three months often predict longer-term patterns. If you have favorable bleeding (infrequent or no bleeding) in the first three months, you are more likely to continue with that pattern. If you experience problematic bleeding, it often improves after 6-12 months, though some women continue to have irregular bleeding throughout use.

Other possible side effects

Headaches are reported by approximately 10-20% of implant users. For most women, these are mild and can be managed with standard over-the-counter pain relievers. If you experience severe or persistent headaches, particularly with visual disturbances, consult your healthcare provider.

Acne and skin changes can occur in some women. The implant may cause acne to develop or worsen in some users, while others may see improvement in their skin. These changes are related to the hormonal effects of progestogen and typically stabilize after the first few months of use.

Breast tenderness is experienced by some women, particularly in the first few months after insertion. This usually resolves as the body adjusts to the steady hormone levels.

Mood changes have been reported by some implant users, including feelings of anxiety, depression, or mood swings. Research on this topic shows mixed results, and it can be difficult to distinguish between effects of the implant and other life factors. If you experience significant mood changes, discuss them with your healthcare provider.

Weight changes are a concern for many women considering hormonal contraception. Studies on the implant show that average weight change is similar to that seen in women not using hormonal contraception. Some individuals may gain or lose weight, but the implant does not cause significant weight gain in most users.

What Are the Benefits of the Contraceptive Implant?

The contraceptive implant offers numerous benefits including exceptional effectiveness (>99.95%), convenience of 3-5 years of protection with no daily action required, immediate fertility return after removal, reduced period pain for many users, and suitability for women who cannot use estrogen. It can also be used while breastfeeding.

The contraceptive implant offers a range of advantages that make it an attractive option for many women. Beyond its exceptional effectiveness at preventing pregnancy, the implant provides several additional benefits that can improve quality of life and simplify contraceptive management.

Convenience and reliability

Perhaps the greatest advantage of the implant is its "fit and forget" nature. Once inserted, you don't need to remember to take a pill every day, apply a patch weekly, or attend appointments for injections. This convenience factor contributes directly to the implant's real-world effectiveness – there is simply no opportunity for user error once the implant is in place.

The implant is also discreet. While you can feel it under your skin if you press on the area, it is not visible and does not interfere with daily activities, exercise, or intimate contact. Most women find they quickly forget the implant is there, only remembering it when asked about their contraception.

Health benefits beyond contraception

Many women experience additional health benefits while using the implant:

• Reduced menstrual pain: Many users report significant improvement in period pain (dysmenorrhea)
• Lighter periods: For women who continue to have periods, they are often lighter than before
• No periods: About 1 in 5 women stop having periods entirely, which some find liberating
• May reduce endometriosis symptoms: The continuous progestogen can help manage endometriosis-related pain
• Protection against ectopic pregnancy: By preventing ovulation, the implant reduces the risk of ectopic pregnancy

Flexibility and reversibility

Unlike permanent sterilization, the implant is completely reversible. If your circumstances change – whether you want to try for pregnancy, experience intolerable side effects, or simply prefer a different method – the implant can be removed at any time. Fertility returns immediately upon removal, with most women who wish to conceive becoming pregnant within a few months, similar to rates seen in women who have not used hormonal contraception.

The implant is also suitable for women in a variety of situations where other methods might be contraindicated or less practical. It can be used by women who:

• Cannot take estrogen-containing contraceptives
• Are breastfeeding (can be inserted from 6 weeks postpartum)
• Have difficulty remembering daily pills
• Experience nausea or vomiting with oral contraceptives
• Travel frequently across time zones
• Take medications that interfere with absorption of oral contraceptives

Who Can Use the Contraceptive Implant?

Most women can safely use the contraceptive implant. It is particularly suitable for those who want long-term, highly effective contraception without daily attention. The implant is safe for breastfeeding mothers, women who cannot use estrogen, and most women with chronic health conditions. However, certain conditions require careful assessment or may preclude use.

The contraceptive implant is suitable for a wide range of women, from those who have never been pregnant to mothers of several children, from teenagers to those approaching menopause. The World Health Organization's Medical Eligibility Criteria provide guidance on who can safely use different contraceptive methods, and the implant has relatively few contraindications compared to combined hormonal methods containing estrogen.

The implant may be particularly suitable if you:

• Want highly effective, long-lasting contraception
• Prefer a "set and forget" method with no daily requirements
• Have difficulty remembering to take daily pills
• Cannot use estrogen due to medical conditions or personal preference
• Are breastfeeding
• Experience significant side effects with estrogen-containing contraceptives
• Have heavy or painful periods
• Are seeking contraception after an abortion or miscarriage

Conditions requiring assessment

Some conditions do not prevent implant use but require careful consideration and monitoring. Your healthcare provider will discuss your individual circumstances if you have:

• A history of cardiovascular disease or stroke
• Multiple risk factors for arterial disease
• Migraine headaches
• Diabetes with complications
• Active liver disease
• A history of depression
• High blood pressure

When the implant should not be used

The implant is not recommended if you:

• Have or have had breast cancer
• Have unexplained vaginal bleeding that has not been investigated
• Have severe liver disease or liver tumors
• Are allergic to any component of the implant
• Are taking certain medications that significantly reduce implant effectiveness

Always discuss your complete medical history with your healthcare provider before starting any new contraceptive method. They can help you weigh the benefits and risks based on your individual circumstances.

How Is the Contraceptive Implant Removed?

Implant removal is a brief procedure performed under local anesthetic. The healthcare provider makes a small incision and uses specially designed instruments to gently extract the implant. The procedure takes 3-5 minutes for straightforward removals. A new implant can be inserted through the same incision if you wish to continue using this method. Fertility returns immediately after removal.

The contraceptive implant should be removed after its approved duration of use (3-5 years depending on guidance in your country), or earlier if you wish to become pregnant, experience intolerable side effects, or prefer to switch to a different contraceptive method. Unlike insertion, which can be performed by trained nurses and healthcare assistants, removal typically requires a more experienced provider, though the procedure itself is still straightforward.

The removal procedure

Before removal, your healthcare provider will locate the implant by feeling your upper arm. In most cases, the implant can be easily felt as a firm line under the skin. Local anesthetic is applied to numb the area around the implant. A small incision (about 2-3 mm) is made at one end of the implant, and the device is gently pushed toward the incision and extracted. The small wound is closed with adhesive strips and covered with a bandage.

Most removals take 3-5 minutes and are straightforward. However, if the implant is not easily palpable (can't be easily felt), additional techniques such as ultrasound or X-ray imaging may be needed to locate it before removal. This is one reason why verification of correct positioning at insertion is important.

After removal

After the procedure, you may experience mild bruising or tenderness at the removal site, similar to after insertion. This typically resolves within 1-2 weeks. The small scar from the incision usually fades over time and becomes barely noticeable.

If you wish to continue using the implant for contraception, a new implant can typically be inserted through the same incision immediately after the old one is removed. This approach minimizes the number of procedures and maintains continuous contraceptive protection.

How Does the Implant Compare to Other Contraceptive Methods?

The contraceptive implant compares favorably to most other methods in terms of effectiveness and convenience. It is more effective than pills, patches, rings, and injections. Unlike IUDs, it doesn't require a pelvic exam for insertion. Unlike pills, its effectiveness isn't reduced by vomiting or forgetting doses. However, unlike IUDs, it cannot be used as emergency contraception.

Choosing a contraceptive method is a personal decision that depends on many factors including effectiveness needs, lifestyle, health conditions, future pregnancy plans, and personal preferences. Understanding how the implant compares to other options can help you make the best choice for your circumstances.

Implant vs. contraceptive pill

Both methods use hormones to prevent pregnancy, but they differ significantly in effectiveness and convenience. The pill requires daily action and has a typical-use failure rate of about 7% (70-90 pregnancies per 1,000 women per year), compared to less than 0.05% for the implant. The pill's effectiveness is reduced by vomiting, diarrhea, and interactions with certain medications – factors that don't affect the implant. However, the pill may offer better cycle control, with more predictable periods, and is easier to stop if you experience side effects.

Implant vs. IUD (coil)

Both the implant and IUDs are long-acting reversible contraceptives with high effectiveness. Hormonal IUDs (such as Mirena) and copper IUDs both have failure rates of about 0.2%, slightly higher than the implant but still excellent. IUDs require a pelvic examination and insertion into the uterus, which some women find uncomfortable or anxiety-provoking. The implant insertion is simpler, requiring only an arm procedure. However, IUDs can be used as emergency contraception if inserted within 5 days of unprotected sex, while the implant cannot.

Implant vs. injection (Depo-Provera)

Both methods use progestogen only and have similar side effect profiles, including effects on menstrual bleeding. The injection requires visits to a healthcare provider every 12-13 weeks, while the implant is inserted once and lasts 3-5 years. The injection has a slightly higher typical-use failure rate (about 4%) due to late injections. One notable difference is that fertility return after stopping the injection can be delayed by several months, whereas fertility returns immediately after implant removal.