The implant (0.1% typical failure, 3 years, upper arm) and IUDs (0.1 to 0.8%, 3 to 10 years, uterus) are the two most effective reversible methods, and the real differences are placement, periods, and hormones.
The implant is a small rod inserted under arm skin with local anesthetic, releasing progestin; its main downside is unpredictable bleeding patterns that some users never settle into. IUDs sit in the uterus: hormonal versions lighten or stop periods and last 3 to 8 years; the copper version is hormone-free, lasts up to 10 years, and can worsen cramps and flow. Placement is usually easier for the implant (arm, numbed, quick) than the IUD (through the cervix, brief but often painful). Both are forget-about-it effective once placed, both are reversible on removal, and neither protects against STIs. Choose the implant for the easiest placement; a hormonal IUD for period control; the copper IUD for hormone-free coverage. If irregular spotting would drive you away, ask specifically about the implant's bleeding profile before choosing it.
What to do
Common questions
Implant vs IUD: how do they compare?
The implant and the IUD are the two most effective reversible contraceptives, and on pregnancy prevention they are effectively tied: the implant fails 0.1% in a typical year, hormonal IUDs 0.1 to 0.4%, and the copper IUD 0.8%. The differences are about where the device lives and how it treats your periods. The implant is a matchstick-sized rod placed under the skin of your upper arm in a quick office procedure with local anesthetic. It releases progestin and lasts 3 years. Its most common complaint is unpredictable bleeding: some people get lighter or no periods, others get irregular spotting that does not settle. The IUD sits in the uterus instead. Hormonal versions last 3 to 8 years and usually lighten or stop periods; the copper version is hormone-free, lasts up to 10 years, and can make periods heavier. Insertion experience differs: the arm implant is generally quick and mild, while IUD placement through the cervix is brief but can be sharply painful. Choose the implant if you want the simplest, least invasive placement and are fine with progestin and possible irregular bleeding. Choose a hormonal IUD if period suppression is the goal, or copper if you want hormone-free. Both are removable anytime, and neither protects against STIs.