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The implant
Revisado: 4 de octubre de 2026
Solo en inglés por ahoraThe implant is a small rod placed under the skin of your arm. It releases a hormone that prevents pregnancy for years, with nothing to remember day to day.
What the implant is
The contraceptive implant is a small plastic rod, about 4 cm long, roughly the length of a matchstick. A doctor or nurse places it under the skin of your arm. It slowly releases progestogen, a hormone that acts like the body's own progesterone. This stops the ovaries from releasing an egg each month, so there is no egg for sperm to reach. The implant does not contain oestrogen.
How well it works
The implant is over 99% effective, as long as it is replaced on time. Because there is nothing to remember, the result is the same with perfect use and typical use: fewer than 1 in 100 people using it get pregnant in a year. That makes it one of the most effective methods there is. How long it lasts depends on local guidance. The NHS says 5 years, and the US Office on Women's Health says up to 3 years. The clinic that fitted yours will tell you when to replace it.
Changes to your bleeding
Irregular bleeding is a known side effect of the implant. Your bleeds may come at different times, or be different from what you are used to. Other possible side effects include headaches, sore breasts and weight gain. If the changes bother you, a doctor or nurse can talk through your options. Logging your bleeding in Ciclo can help you see the pattern and describe it clearly at an appointment.
Removal and your fertility
A doctor or nurse can take the implant out when you want to stop using it or when it needs replacing. Once it is removed, your chance of getting pregnant goes straight back to what it was before it was fitted. The implant does not protect against sexually transmitted infections (STIs), so condoms are still worth using if STIs are a concern.
When to talk to a doctor or nurse
Talk to a doctor or nurse if side effects or bleeding changes bother you, or if your implant is close to its replacement date. Bleeding after sex should always be checked. Without regular bleeds, it can be harder to notice a pregnancy. If you have possible signs such as feeling sick, sore breasts or unusual tiredness, take a pregnancy test or talk to a doctor or nurse.
This is general information. A doctor or nurse can tell you whether the implant suits you and when yours needs replacing.