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Contraceptive injection

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What is the contraceptive injection?

The contraceptive injection releases the hormone progestogen into your blood stream which prevents pregnancy. In the UK there are three brands of injection Depo-Provera, Sayana Press and Noristerat, however Depo-Provera is the most commonly used. The Depo-Provera and Noristerat injections are usually injected into your bottom, however you can have them in your upper arms. Whereas Sayana Press is injected into your abdomen (tummy) or thigh, you may be able to do this yourself after being shown how to do so.

How does the contraceptive injection work?

The injection usually lasts for 8 or 13 weeks, the most commonly given is the depo injection which lasts for 13 weeks. During this time it slowly releases the hormone progesterone into your body. This hormones prevents your body from releasing an egg every month, this is known as ovulation. The hormone also thickens the cervical mucus within your cervix making it difficult for sperm to reach an egg. The womb lining is also thinned so that a fertilised egg finds it difficult to implant itself onto the wall of your womb.

How long does it take the contraceptive injection to work?

As long as you’re not pregnant you can have the injection at any time during your menstrual cycle, although in order to be immediately protected you need to have the injection during the first five days of your cycle. If you have the injection on any other day of your menstrual cycle you’ll need to use additional contraception for seven days afterwards.

If you are planning to get pregnant and have stopped using the injection it can take a year or so for you to get pregnant. There may be a delay of up to a year before your periods return to normal and you start ovulating again.

How effective is the injection?

When used correctly the contraceptive injection is more than 99% effective.* It’s important that you have your next injection at the right time, if you are late or miss the next one you may not be protected against pregnancy. The injection also does not protect against STIs (sexually transmitted infections), you may wish to use a barrier method of contraception such as condoms to reduce your risk of catching an STI.

What are the side effects of injectable contraceptives?

Many women chose to have the injection because it may help to reduce heavy and painful periods as well as ease premenstrual symptoms. However as with any method of birth control there are side effects that you should consider before you make a decision.

Side effects can include:

  • Periods – you periods may become irregular, heavier, shorter, lighter or stop altogether. These changes can carry on for some months after you discontinue using the injection
  • Spotting  you may continually bleed when you’re not on your period
  • Weight – you may put on weight due to a change in appetite. This is one of the side effects of the depo injection and is connected to the sayana Press too
  • Headaches
  • Acne
  • Breast tenderness
  • Hair loss
  • Sex drive – you may lose interest in sex
  • Mood swings

These side effects can last as long as the injection does and they can continue for some time after you have stopped using the contraceptive injection. Once you have come off of the injection it can take a year for your periods to go back to normal.

Where can I get the injection?

You can get the injection for free at your local sexual health clinic, contraception clinic, GP surgery as well as young people’s services. You can use the NHS search tool to find your nearest sexual health clinic, you may want to book an appointment or attend a drop-in session. You will need to keep going back to the same clinic or doctor’s surgery every time that you have the injection.

Are there any risks associated with the contraceptive injection?

Similarly to the implant there is a small risk that the site of the injection becomes infected, however this is very rare. As long as you keep the wound clean and dry you should not have any problems with the injection. In some cases women can have an allergic reaction to the injection, if this occurs speak to your healthcare practitioner who will be able to advise you and help you to find another contraceptive method.

Who can get the injection?

Most women will be able to have the injection as their chosen method of birth control, however if you have a fear of needles or do not like having injections it is probably not the best option for you. Your doctor or nurse will be able to talk you through the injection and discuss if it is suitable for you, for example if you don’t want your periods to change you may need to consider other contraception.