Contraceptive injection

The contraception jab protects you from pregnancy for up to three months. But does the injection hurt? Can it screw up your periods? And can you un-do it if you don’t like it? Here’s what you need to know.

a picture of a syringe

Is the contraceptive injection for you?

What is the contraceptive injection?

It’s an injection of hormones that works in the same way as the progestogen-only pill: it stops the ovaries releasing eggs and thickens the cervical mucus making it virtually impossible for sperm to get through. It also thins the lining of the womb, so if a sneaky sperm manages to fertilise an escapee egg it has nothing to hold onto.

There are two brands available in the UK: Depo-Provera, which lasts for three months, and Noristerat, which lasts for two months. Both methods are over 99% effective.

Does the injection hurt?

Unless you have skin like a rhinoceros it stings a bit and you may feel a bit bruised afterwards, but that’s it. It’s injected into the muscle – usually on your bum or upper arm. Your bum is supposed to be less painful, so speak up if you have a preference.

You can have one at any time. If you have it during the first five days of your period you’re protected straight away. If you have it any other time of the month, however, you’ll still need to use condoms for at least seven days.

Will the injection make my periods worse or stop them?

As with any hormonal contraception, it’s likely to throw a spanner in your menstrual works. You could get irregular and possibly heavy bleeding, to lighter or non-existent periods. Unfortunately there’s no way of knowing how the injection will affect yours until you try it.

Annoying as this period lottery sounds, your cycle should settle down after a few months. After a year’s use your period could stop all together. This may seem a bit freaky, but it happens to roughly 70% of users and is completely normal, so there’s no need to panic.

Will I put on weight if I’m on the injection?

We’re not going to lie to you, for some unexplained reason the answer is yes, it probably will. But you’re unlikely to gain LOADS.

“When you look at the average weight gain we’re talking about small numbers (7lbs over 2 years), but no one’s come up with a sensible evidence-based reason for it,” says Lynn Hearton at FPA. “It’s often down to where you are on the weight scale before you start using it, so it’s a question of considering the pros and the cons and working out what’s best for you.”

What if I hate it?

Unfortunately there’s no antidote for the contraceptive injection. So if you’ve turned into the Wicked Witch from the West with a perma-period then it will last until the jab wears off – and possibly for some time afterwards.

How long before my fertility returns?

It varies from woman to woman, but for most you’re talking between five to six months after the last injection. Rarely, it can take up to two years before fertility returns.

Are there any risks?

There’s a small risk of an infection at the site of the injection and, rarely, some women may have an allergic reaction.

Other long-term risks, such as links to breast cancer and osteoporosis, are speculative and research is ongoing.

Anything else to worry about?

You have to remember to get the shot every two to three months. If you forget, or can’t make an appointment, you’ll lose your protection.

And remember, this won’t protect you against STIs. So make sure you’re both tested before you chuck the condoms in the bin.

Can anyone have the injection?

Most women can have the injection, but your GP or nurse at the family planning clinic will go through your medical history to make sure it’s suitable for you. There are a few reason why it may be unsuitable, these include:

  • If you think you’re pregnant
  • If you have breast cancer or undiagnosed breast lump
  • If you have liver disease

Next Steps

  • FPA give sexual health advice. For Northern Ireland helpline call 0345 122 8687.
  • Brook's Contraception tool helps you work out best contraceptive method for you.
  • Chat about this subject on our Discussion Boards.
  • Need help but confused where to go locally? Download our StepFinder iPhone app to find local support services quickly.

By Nicola Scott

Updated on 29-Sep-2015