The Pros and Cons of the Contraceptive Injection: Is It Right for You?

The contraceptive injection is a type of birth control that slowly allows progestogen hormone into your bloodstream to stop pregnancy. It is often known by trade names such as Depo-Provera,  Noristerat or Sayana Press.

What is the Contraceptive Injection?

Depo-Provera, the most widely used contraceptive injection in this country, lasts for 13 weeks. Sometimes, Noristerat may be prescribed, which lasts for 8 weeks. Sayana Press, a newer form of the injection, is also available at some clinics and lasts for 13 weeks.

How Effective is the Contraceptive Injection?

If used correctly, the contraceptive injection is more than 99% effective in preventing pregnancy. It is effective for either 8 or 13 weeks, depending on the type of injection, so you needn’t worry about contraception everyday or each time you decide to have sex during this time.

How Does the Contraceptive Injection Work?

The jab releases a slow dose of progesterone hormone into your bloodstream, which stop ovulation, and the release of an egg, each month. It also makes the cervical mucus thicker, making it near impossible for sperm to swim through the cervix, and it also thins the lining of the womb, which makes it a lot or difficult for a fertilised egg to get implanted.

When Does the Contraceptive Injection Start Working?

You can have the injection at any time during your menstrual cycle, as long as you’re not pregnant. If you have the injection in the first 5 days of a menstrual cycle, you’ll be protected against becoming pregnant immediately. If you have the injection on any other day of your cycle, you’ll need to use extra contraception, such as condoms, for 7 days.

Who is the Contraceptive Injection Suitable For?

Nearly all women are able to receive the contraceptive injection. However, it may not be right for you if you suspect that you could be pregnant, don’t want your periods to change, are considering trying for a baby in the next year, have bleeding in between periods that is unexplained or post sex, have liver disease, have disease of the arteries or a history of stroke or heart disease, have breast cancer or a history of having it, or are at risk of osteoporosis.

Advantages and Disadvantages of the Contraceptive Injection


  • Each injection lasts for either 8 or 13 weeks.
  • It allows sex without interruption.
  • It’s a choice if you are unable to use oestrogen-based contraception.
  • You don’t have to remember to take a pill every day.
  • It’s safe to use while you’re breastfeeding.
  • It’s not affected by other medicines.
  • It can lessen heavy, painful periods and help with premenstrual symptoms for some women.


  • Your periods may change. They might become irregular, shorter, heavier, lighter, or stop altogether – this can carry on for some months after you stop the injections.
  • It does not protect you against sexually transmitted infections (STIs).
  • There can be a delay of up to 1 year before your periods return to normal and you can become pregnant.
  • Depo-Provera or Sayana Press contraceptive injections can cause weight gain in some women
  • You may experience side effects like acne, hair loss, headaches, lowered sex drive, and mood swings.
  • Any potential side effects can carry on for as long as the injection lasts (8 or 13 weeks) and for some time after.


There’s a small risk of infection in the area of the injection. In some very rare cases, some women may have an allergic reaction to the injection. Using Depo-Provera changes the natural oestrogen levels in your body. This can cause thinning of the bones, but it does not increase your risk of breaking a bone. Sometimes, the doctor may recommend that you stop after 2 years to prevent any long-term effect on your bones.

Where Can You Get the Contraceptive Injection?

You can obtain the contraceptive injection for free, even if you’re under the age of 16, from genitourinary medicine (GUM) clinics, contraception clinics and GP surgeries, and some young people’s services. Sayana Press is available in some clinics, and you’ll be shown how to give yourself the injection, rather than needing a doctor or nurse give it to you.

If you’re under 16 years old, contraception services are free and confidential, including for people under the age of 16. Doctors and nurses follow strict guidelines when dealing with people under 16 and will not tell your parents (or carer) as long as they believe you fully understand the information you’re given and the decisions you’re making.

In conclusion, the contraceptive injection is a highly effective, long-lasting solution for birth control, offering several advantages but also some potential disadvantages and risks. It’s essential to weigh the pros and cons carefully and discuss with a healthcare professional to determine if it’s the right choice for you.

Photo credit; “Injection” by Anthony Cunningham for Zoom Baby

Zoom Baby is a leading supplier of Pregnancy Tests and Ovulation Test Kits

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