• Works for up to 13 weeks (depending on type used).
  • You don’t have to prepare for or interrupt sex.
  • You don’t have to remember to take a pill everyday.
  • Not affected by other medicines.
  • May provide some protection against cancer of the womb and pelvic inflammatory disease.
  • Suitable for women who can’t take oestrogen.
  • May help with premenstrual symptoms.
  • May reduce heavy or painful periods.
  • Fertility returns to normal after the injection wears off.

The contraceptive injection contains the hormone progestogen and offers medium term prevention of pregnancy. It is the fifth most popular method of contraception in the UK.

Lasts for
8,12 or 13 weeks
Period cycle**
Side effects

*for typical use (effectiveness for perfect use 99%)

**lighter over time (70% people won’t bleed at all by the end of the first year)

How it works

How to use it

There are 3 types of injection available in the UK:

  • Depo Provera is the most common and lasts for 13 weeks;
  • Sayana Press lasts for 13 weeks;
  • Noristerat lasts for 8 weeks.

A doctor, nurse or clinician will inject you, either in the muscle of your bottom or upper arm (Depo Provera/Noristerat), or into the skin of the thigh or abdomen (Sayana Press). Sayana Press may be administered by a healthcare professional (HCP) or, when considered appropriate by the HCP, self-injected by the patient, with medical follow-up as necessary in accordance with local clinical guidance.

Once you’ve had the injection, you don't have to think about contraception for the specified period, though you should make a note of when it will wear off.

Why it works

The injection prevents pregnancy by:

  • Preventing the ovaries from releasing an egg each month (ovulation)
  • Thickening the mucus in the neck of the womb, so it is harder for sperm to penetrate the womb and reach an egg
  • Thinning the lining of the womb, so there is less chance of a fertilised egg implanting into the womb.

Things to consider

The contraceptive injection does not protect you from STIs. You should use a condom as well if you think you are at risk of an STI.

It can take up to one year for your fertility and periods to return to normal after the injection wears off, so it may not be suitable if you want to have a baby in the near future.


Most women can use the contraceptive injection, but your clinician will ask about your family and medical history to determine whether or not it is the best method for you.

The injection is not suitable for women who:

  • are pregnant;
  • want to become pregnant within the next year;
  • want regular periods;
  • have bleeding in between periods or after sex;
  • are at risk of osteoporosis.

It may not be suitable for women who have or have had certain health conditions.

Side effects & risks


Short term:

Weight gain, headaches, mood swings, breast tenderness and irregular bleeding.

Long term:

Periods may become more irregular or longer, or stop altogether. By the end of the first year of injection use 70% of women are having no bleeding at all.


Short term:

Allergic reaction to the injection is possible but rare.

Risk of a small infection at the site of the injection is rare.

Long term:

Using Depo Provera affects your natural oestrogen levels, which can cause thinning of the bones if used for an extended time.

Irregular bleeding may continue for some months after you stop the injections.


Why does the injection affect my periods?

The hormone in the injection prevents you ovulating and going through a normal menstrual cycle.

How quickly will the injection start to work?

If you have the injection during the first 5 days of your period, you will be immediately protected against becoming pregnant.

If you have the injection on any other day of your cycle, you will not be protected against pregnancy for up to 7 days. Use condoms or another method of contraception during this time.

What happens if I get the injection late?

If you think your next injection is late, use condoms until you know that your injection is definitely protecting you again.

If you have had unprotected sex and are worried you may need to use emergency contraception.

What is the difference between the contraceptive injections?

There are 2 types of injections available from Sexual Health Dorset: Depo Provera and Sayana Press. With Depo Provera you need to see us every 13 weeks to have a new injection. With Sayana Press you can manage these at home for up to a year after a full assessment.

What if I have the injection and then do not find it suitable?

Once it is inserted you cannot remove the injection but its effects will wear off after 8-13 weeks, depending on the type used.

Will the contraceptive injection affect my future fertility?

It can take up to one year for your fertility and periods to return to normal after the injection wears off, so it may not be suitable if you want to have a baby in the near future.

Irregular bleeding may also continue for some months after you stop the injections.

Does getting the contraceptive injection hurt?

It is similar to getting any other injection such as pre-travel vaccinations.

I am approaching menopause; can I have the Injection?

Women over the age of 50 should consider alternative methods of contraception. Women approaching the menopause should discuss their risk of osteoporosis with their healthcare provider.

Will there be any long-term effects on my health?

Some research has shown Depo Provera is associated with a small loss in bone mineral density, which then returns to normal within a few years of stopping the injection.

Can I have the injection after having a baby?

Yes, the injectable contraception can be used after having a baby.

Can I have the injection while breastfeeding?

Yes, the injectable contraception can be used safely while you are breastfeeding and will not affect your milk supply.

I’ve had a serious health condition; can I use the contraceptive injection?

The injection may not be suitable if you have or have had any of the following:

  • liver disease;
  • risk factors for osteoporosis;
  • breast cancer;
  • systemic lupus erythematosus;
  • if you are under 18 or over 50 years.

Speak to your clinician about whether it is suitable for you.

To make an appointment or for further advice, please call:

0300 303 1948

Phoneline open 08:15-16:45 Monday-Friday

(closed 12:30-13:30 for lunch)