2017, Responses from: Prof Neil Johnson

How does the Zoladex injection affect my period? For instance, I thought it would stop my periods but that hasn’t happened.

Prof Neil Johnson: It can sometimes take a cycle or two for Zoladex – which is a GnRH agonist and works by switching off the pituitary gland releasing the hormonal drive to the ovaries – to stop menstrual bleeding, although most women’s periods have stopped by the second cycle of treatment.

My doctor has suggested I start a course of Zoladex but from what I have read, it’s a pretty gross drug with awful side effects. Wouldn’t it be better to excise my endometriosis properly as I have only had a diagnostic laparoscopy?

Prof Neil Johnson: Zoladex does have potential side effects, including hot flushes, sweating episodes, vaginal dryness and mood swings or low mood, and if used longer term also loss of bone mass – in other words, menopause-type side effects – but some women experience little in the way of side effects. When given to treat pain symptoms, Zoladex is usually administered with add-back hormone therapy, usually involving estrogen and progestin hormone, which means that most women will not have any Zoladex-related side effects. When given to assist fertility outcomes, such as in the lead in to IVF, Zoladex is usually given without add-back hormone therapy, but the duration of the treatment course is usually short, typically only three months.

Is Zoladex the same as that horrible drug Lupron that they talk about in the U.S.?

Neil Johnson: Both Zoladex and Lupron are GnRH (gonadotrophin releasing hormone) agonists (or analogues). However both, if used properly as described in reponse to query (b), in most cases, neither tends to be horrible. They can both have side effects, but even if this is the case, often this is quite manageable. If not, then there are other treatment options.


ENZ does not give advice on any medical therapies or drugs to treat endometriosis. There are no drugs which cure endometriosis but women often find their symptoms are controlled or improve taking certain drugs. Our recommendation is that you research the drugs being recommended to you. Ask your doctor why that particular drug is being recommended and the options available. Any treatment you are offered is about YOUR INFORMED CONSENT.

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