This page gives you advice and information about Prostap® or Zoladex® treatment for non-cancerous gynaecological conditions such as fibroids, endometriosis and severe Premenstrual Syndrome (PMS) or Premenstrual Dysphoric Disorder (PMDD). Please see below for explanations of these conditions.

How does this treatment work?

Prostap® or Zoladex® are gonadotrophin-releasing hormone (GnRH) agonists. They temporarily stop your ovaries from functioning and therefore stop the hormone oestrogen being produced.

By temporarily reducing oestrogen levels, fibroids or endometriotic deposits can shrink over a period of time. The treatment also prevents the regrowth of the endometrium (lining of the womb). As Prostap® or Zoladex® also stops the normal ovarian hormone cycle, related cyclical symptoms such as PMS and PMDD can improve.

When is the medication used?

  • Fibroids – this treatment can reduce their size and improve symptoms. Reducing the size can make some surgery easier and reduce surgical blood loss. This treatment is not generally recommended prior to abdominal myomectomy (removing fibroids through the abdomen).
  • Endometriosis – this treatment can reduce the extent of endometriotic deposits, which helps prior to surgery. It can provide symptom relief. In severe cases of pelvic pain, it can also be useful in establishing if this is related to ovarian function, and perhaps that removing the ovaries would be of benefit.
  • PMS/PMDD – the treatment can help diagnose and treat (shorter-term) severe premenstrual symptoms, particularly when other medications have been unsuccessful or are not appropriate.
  • To help diagnose the cause of gynaecological symptoms – as the medication stops most natural production of oestrogen and the normal hormonal cycle, it can be used to see which symptoms are likely to be related to a patient’s hormones/cycle.
  • To keep the lining of the womb thin/stop bleeding – occasionally the treatments are used to stop menstrual bleeding or to thin the womb lining prior to a specific type of endometrial ablation.

What are the side effects?

Most of the side effects are due to the temporary menopausal symptoms brought on by the medication. These include:

  • Hot flushes
  • Sweats
  • Vaginal inflammation/dryness
  • Headaches
  • Reduced sex drive
  • Emotional changes
  • Depression
  • Acne
  • Decreased bone density (thinning of the bones) if used for a long period of time, especially without HRT

Your consultant will discuss additional medication that can reduce these menopausal symptoms.

In addition, some symptoms such as irregular vaginal bleeding and a flare up of symptoms such as pelvic pain can occur after the first injection. These usually completely settle by the second injection.

As the medication is an injection, bruising and redness around the injection site may occasionally happen.

How long can this treatment be given?

Generally patients can use the medication for up 6 months without any significant issues around thinning of bone (ostepaenia/osteoporosis).

It is however possible to use the medication for longer, for example, more than 12 months when no other suitable treatment options are available. If this is the case your consultant will discuss the pros and cons with you. They will also talk about any additional monitoring that may be required such as bone scans, and give general advice regarding bone health including Vitamin D and calcium supplements.

How are the injections given?

They are usually started within a week or so after your period has finished. This can reduce the amount and duration of irregular bleeding experienced after the first injection.

The injections are given under the skin (sub-cutaneous) in the lower part of your tummy every 4 weeks. Your consultant will discuss with you if it is appropriate for you to have a 3 monthly injection of the same medication instead.

Does Prostap® or Zoladex® provide contraception?

Although most women stop having periods during treatment, the medication does not provide effective contraception, so you will need to continue with alternative methods. Generally speaking, these should not contain the oestrogen hormone such as the combined oral contraceptive pill. The mini-pill (progesterone only) can be used.

Will the treatment affect my fertility?

No. Once the course has been completed, your fertility will return to your pre-treatment level, depending on what other treatments you have.

Who cannot have this treatment?

Women who are:

  • Pregnant
  • Trying to conceive
  • Breastfeeding

What happens when the injections are stopped?

The medication wears off after 5 to 6 weeks at which stage your ovaries begin to start working again. Symptoms which the injections have helped with may start to gradually return.

What are the alternatives to this treatment?

There may be alternatives to this treatment, such as hormonal medications. Your consultant will discuss this with you.


Royal College of Obstetricians and Gynaecologists


Endometriosis UK


Printable version of this page

Prostap® and Zoladex® injections GHPI1710_02_22 Department: Gynaecology Review due: February 2025 PDF, 162.3 KB, 4 pages
Reference number GHPI1710_02_22
Department Gynaecology
Review due February 2025