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How treatment with Zoladex works

To understand how Zoladex works, you first need to understand the simple steps behind the growth of prostate cancer itself:

  • Prostate cancer cells need the male hormone ‘testosterone’ to grow1
  • A substance called ‘luteinising hormone releasing hormone’ (LHRH) causes the
    release of another substance, luteinising hormone (LH), from the pituitary gland in the brain2
  • This in turn causes the testes to release testosterone (which prostate cancer needs to grow)2

Zoladex works by reducing the amount of testosterone produced by the testes.
This is described here in 3 steps:

  1. Zoladex mimics LHRH, causing an initial increase in the levels of LH and hence testosterone2
  2. However, after a while, the body quickly becomes ‘desensitised’ to the artificial Zoladex LHRH, and the level of LH falls dramatically, and so does the level of testosterone2
  3. Without testosterone, prostate cancer cells are “starved” of a vital ingredient for growth2

Zoladex will not make the cancer go away completely, but it can shrink the prostate tumour, relieving symptoms of the cancer and halting or slowing the growth of the tumour.2

Reporting of side effects

Like all medicines, Zoladex can cause side effects, although not everybody gets them.

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the Yellow Card Scheme, Website: By reporting side effects you can help provide more information on the safety of this medicine.

  1. Cancer Research UK: About hormone therapy for prostate cancer:
    (Accessed July 2017).
  2. Gomella Vol 11 No 2009 pg 52-60.

GB-6242. Date of Preparation: Sept 2017