contraceptive injection
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How a contraceptive injection works?


What is contraceptive injection?

The contraceptive injection is a shot of hormones containing either only progestin or a combination of progestin and estrogen, which stops the release of eggs by the body and thickens the mucus at the cervix. A shot per month or every three months from a healthcare provider is all that’s required. It is, however, irreversible once injected; that is, should side effects arises, it cannot be stopped. 

Why is it used?

The contraceptive injection is simply used to prevent pregnancies and manage medical conditions related to the menstrual cycle. It is also used in place of a birth control pill.

Types of contraceptive injection 

There are about 3 types of contraceptive injections. 

  • Depo Provera: A contraceptive injection that prevents pregnancy for 13weeks. The injection is repeated after expiration and it’s important to get it on time. 
  • Sayana Press: This contains the same hormone as Depo Provera but given under the skin rather than into the muscle. It also lasts for 13 weeks. 
  • Noristerat: This contraceptive injection contains different progesterone than Depo Provera. This, however, only offer protection for 8 weeks, after which it has to be repeated. Therefore, it is not as commonly prescribed.

How a contraceptive injection works 

A contraceptive injection prevents pregnancy in three different ways:

  • It prevents ovulation: A contraceptive injection gradually releases the hormone progesterone into the bloodstream. This stops the ovaries from the release of eggs each month. By so doing, there is no egg for the sperm to fertilize.
  • It thickens the mucus in the cervix (the neck of the womb): It thickens the cervical mucus. This thickness makes the mucus partially block the entrance to the womb (uterus). This makes it harder for sperm to penetrate and fertilize an egg.
  • It thins the lining of the womb: This makes it less likely for a fertilized egg to implant itself into the womb to create a pregnancy.

How the contraceptive injection is given 

  • The injection is given in the muscle of the buttock or the upper arm.
  • The best period to take the injection is during the first 5 days of a period. This prevents pregnancy straight away.

Who uses a contraceptive injection?

Most women can use a contraceptive injection. However, it may not be suitable if;

  • You think you might be pregnant.
  • You don’t want your periods to change.
  • You plan to have a baby soon.
  • You experience unexplained bleeding in between periods or after sex.
  • You have arterial disease or a history of heart disease or stroke.
  • You have liver disease.
  • You have breast cancer or have a history.
  • You are at risk of osteoporosis.

Advantages of a contraceptive injection

  • It is long-lasting, up to 3 months.
  • It doesn’t cause sex interruption.
  • It offers an alternative for those that can’t use estrogen-based contraception.
  • You don’t stress remembering to take a pill every day.
  • It’s safe for use during breastfeeding.
  • It’s unaffected by other medicines.
  • It may help to reduce heavy, painful periods and help with premenstrual symptoms for some women.
  • Its use can’t be detected by other people

Disadvantages of a contraceptive injection 

  • It may change and alter the regularity of periods; such as becoming heavier, shorter, lighter or stop altogether.
  • It doesn’t offer protection against STIs.
  • It may take up to 1 year after stoppage before normalcy returns to period and pregnancy can take place.
  • Unnecessary weight gain, especially if Depo-Provera or Sayana Press contraceptive injections are used.
  • It may lead to headaches, acne, hair loss, decreased sex drive, and mood swings.
  • Loss of bone density may occur if the shot is taken for more than 2 years in a row.
  • It entails keeping track of the number of months used.


Where can I get a contraceptive injection

A contraceptive injection can be gotten from your local doctor or from a Family Planning clinic.

How well does a contraceptive injection work? 

A contraceptive injection is highly effective at preventing pregnancy. It offers up to 99.8% effectiveness if taken at the correct time every 12 weeks, but if otherwise, it can be around 96%.

What if I want to get pregnant after using a contraceptive injection? 

If you want to get pregnant after using the contraceptive injection, then you will need to stop taking the contraceptive injection immediately as it usually takes about 6-9 months for periods to go back to normal, and before fertility can occur.

Are there any contraceptive injection side effects? 

Some contraceptive injection side effects include;

  • Headaches.
  • Bloating.
  • Skin problems; such as acne.
  • Sore or tender breasts.
  • Mood changes.
  • Abdominal pain.
  • Weight gain.
  • Nausea and dizziness.
  • Fluid retention.
  • Weakness.
  • Decreased interest in sex.
  • Depression.
  • Irregular periods and breakthrough bleeding
  • Nervousness.
  • Weakness and fatigue.

Are there any contraceptive injection complications?

Possible contraceptive injection complications are;

  • There’s a minor risk of infection at the site of the injection. 
  • Although in very rare cases, some people may develop an allergic reaction to the injection.
  • Delay in returning to fertility. 
  • It might have an effect on bone mineral density.

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