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WTF Is Zoladex Anyway?

This is one of the questions that I get asked on a regular basis and it's not difficult to understand why. Wherever you look on social media, I guarantee there is a post about the horrors of Zoladex and why it shouldn't be considered as a treatment option for those of us who have endometriosis.

So why am I adding fuel to the fire? I'm fed up of the misinformation and blatant lies that get spread about Zoladex and now that I've been taking it for 7 months, I feel confident that I can give an honest opinion on how it has helped me and my endometriosis.

Now I fully appreciate, accept and understand that of course there's going to be individuals who have had negative experiences with Zoladex (what medication doesn't?!) and it's incredibly important for that to be shared but that's different to people spreading information that is utter bull crap. But the idea of an individual making a medical decision based on incorrect information isn't okay, hence this post.

So, most importantly: WTF is Zoladex?

Zoladex is the brand name of the drug Goserelin (pronounced goo-sir-relin), is part of a family of medicines called Gonadotrophin Releasing Analogues (GnRHa) and is a type of hormone therapy. In short, GnRha's essentially temporarily stop the ovaries from producing oestrogen (University College Hospitals London, 2020).

The longer explanation is that within our hypothalamus we create gonadotrophin-releasing hormones, these are carried to the pituitary gland and stimulate the production of two more hormones – follicle stimulating hormone and luteinising hormone (Society for Endocrinology, 2018). The latter is known as a gonadotropic hormone which controls the function of the ovaries and testes - also known as gonads, hence where the name 'gonadotrophin' stems from (Endocrine Society, 2018). Zoladex works by interfering with those hormone signals and switches off the production of the luteinising hormone which it turn stops your ovaries from producing oestrogen.

As a result it's often used in patients who have prostate or breast cancer, individuals with uterine fibroids or individuals with fertility issues.

I've heard that Zoladex is actually a chemotherapy drug, is that true?

NOPE. I would apologise for the capitals but this is the most dangerous misconception that seems to circulate when Zoladex is brought into the conversation. Zoladex is a hormone therapy drug, not a chemotherapy drug. In fact, Zoladex can and often is administered alongside chemotherapy treatments but they are not the same thing (MacMillan, 2020).

The information pamphlet that comes with a Zoladex injection specifically states: 'Zoladex 3.6 mg is indicated as an alternative to chemotherapy in the standard of care for pre/perimenopausal women with oestrogen receptor (ER) positive early breast cancer' (Electronic Medicines Compendium, 2020). Whilst this isn't specific to endometriosis, I hope you get the point.

So I repeat, whilst Zoladex is used to treat some cancers it is NOT a chemotherapy drug.

I've heard that Zoladex is the same as Lupron, is that true?

Similar, yes. The same, no. Lupron (generic name, Leuprolide) is part of the same family of GnRHa's but it's a different man-made hormone. Both work in the same way by stopping the ovaries producing oestrogen but from my research it seems that Lupron has a much higher list of side-effects than Zoladex does (Cunha, 2019)(, 2020).

Why is it recommended to help individuals with endometriosis?

Endometriosis is a oestrogen fed condition and Zoladex stops the production of oestrogen in your ovaries. Whilst endometriosis creates its own oestrogen, Zoladex can help slow the growth of it by cutting off the supply from the ovaries and/or potentially shrink the existing endometriosis that has grown in your body (University College Hospitals London, 2020). Zoladex can also be administered in preparing for a laparoscopic surgery as it thins the lining of the uterus and can reduce the inflammation caused by endometriosis (Electronic Medicines Compendium, 2020). In either situation, Zoladex can reduce endometriosis pain and the associated flares it causes.

From a personal point of view, I've now been taking Zoladex for 7 months and will continue to do so until my next laparoscopy goes ahead (19/10/2020). I was recommended to start taking it in prep for the aforementioned surgery to thin the lining of my uterus and reduce any inflammation my endometriosis has caused. This wasn't a decision I took lightly but I trusted my gynaecologist and her medical advice.

How is it taken?

The Zoladex injection is a depot injection, meaning that it the drug is slowly released into your body over a period of time, in the case of Zoladex, this is 28 days. It comes as an implant (it's very small) in a pre-filled syringe which is then injected subcutaneously (into the fatty layer of our skin) of your abdomen; I was provided with a numbing cream and you're well within your rights to ask for this too.

It is taken every 28 days, usually for up to 6 months depending on your circumstances. However, this doesn't mean it's unsafe if you need to take it longer. Breast cancer patients can and will have it administered for up to 5 years but can be taken indefinitely (Breast Cancer Now, 2020). As aforementioned, at the time of this blog post, I've been on it for 7 months.

I've heard that it can affect my fertility, is that true?

With any drug that interferes with your reproductive hormones, there is a very rare risk that it could effect your fertility in the long run. However, Zoladex is often prescribed to individuals as a way of preserving their fertility whilst under going chemotherapy because it temporarily shuts down the ovaries. As highlighted by the Moore et. al (2018), their study on Zoladex and infertility in breast cancer patients showed that individuals treated with Zoladex in addition to chemotherapy before surgery were much less likely to be infertile after chemotherapy ended.

Once you stop taking Zoladex your ovaries will start to produce oestrogen again and most individuals state that their periods return within three to twelve months (Breast Cancer Now, 2020). At this point I'll also mention that even though Zoladex puts you into a temporary menopause, it is not a contraceptive; so continue to practise safe sex - whatever that means for you!

How does it feel to be on it?

Much better than not being on it! The first three weeks it's normal to expect your hormone levels to increase before decreasing to that of a someone who is post-menopausal (WebMD, 2020). For said three weeks I just felt like I was PMSing, my emotions were rocky but it was easy to deal with as I expected that to happen. Once my body had adjusted to the Zoladex I found that my pain was minimal and that I flared less often and with less intensity.

What are the side effects?

As with any medication, there are of course side effects. For the most part, Zoladex can trigger post-menopausal symptoms such as hot flushes, a drop in libido, vaginal dryness, mood changes, vaginal bleeding, etc. The biggest factor for me was that prolonged use of Zoladex can decrease your bone density and therefore your changes of getting osteoporosis; as I've been on it for over 6 months I was recommended to take HRT alongside it to prevent this from happening. The worst side effect for me was the hot flushes but I have always been prone to them due to my under-active thyroid.

Personal experience aside, Zoladex can cause your bone density to decrease on average by 1% per month during a six month treatment period (AstraZeneca, 2020). However, what doesn't get discussed is that individuals who are going through the menopause will naturally lose up to 20% of their bone density (National Osteporosis Foundation, 2021). So whilst Zoladex can speed this process up, it's not causing the body to go through a process that wouldn't naturally happen anyway. With that in mind, this is why both menopausal individuals AND individuals who are on Zoladex are offered to take HRT (to add back the oestrogen) as research shows that when individuals are offered both in combination there is 'no significant change in bone density' in comparison to individuals who are on Zoladex alone (Leather, Studd & Holland, 1993).

I've also had quite the rainbow bruise after the actual injection but I think that's pretty minor and some tenderness afterwards is normal.

What would you suggest to someone who has been recommended to take Zoladex?

Do your research and don't just listen to the information that is shared via social media. There is a wealth of information out there linked to Zoladex and all of my listed references were found very quickly via google. Only you know what is right for your body and if you think that you do/don't want to take Zoladex for whatever reason that is your choice. Likewise, remember that you are always entitled to a second (or third, even fourth!) opinion.

Regardless of your opinion on Zoladex, I hope that this post has been useful to you.

Final disclaimer: I am in no shape or form a medical professional and the opinions expressed are my own. Whilst this post is intended to be educational, please consult your doctor regarding any decisions linked to your health. For my full disclaimer, click here. For more information regarding Zoladex, see my references below, click here to go to the Zoladex website or here for the Zoladex pamphlet .



  1. AstraZeneca (2020) Zoladex. [Online] Available from: [Accessed 4 October 2020].

  2. Breast Cancer Now (2020) Goserelin (Zoladex) [Online] Available from: [Accessed 4 October 2020].

  3. Cunha, J. (2019) Zoladex Vs. Lupron. [Online] Available from: [Accessed 4 October 2020].

  4. (2020) Comparing Goserelin vs Leuprolide. [Online] Available from: [Accessed 4 October 2020].

  5. Electronic Medicines Compendium (2020) Zoladex 3.6mg Implant [Online] Available from: [Accessed 4 October 2020].

  6. Endocrine Society (2018) What is Luteinizing Hormone? [Online] Available from: [Accessed 4 October 2020].

  7. Leather, A., Studd, J. & Holland, E. (1993) The prevention of bone loss in young women treated with GnRH analogues with "add-back" estrogen therapy. Obstet Gynecol. [Online] 81 (1), 104-107. Available from: [Accessed 20 July 2021].

  8. MacMillan (2020) Goserelin For Men (Zoladex) [Online] Available from: [Accessed 4 October 2020].

  9. Moore, H., Unger, J., Phillips, K., Boyle, F., Hitre, E., Moseley, A., Porter, D., Francis, P., Goldstein, L., Gomez, H., Vallejos, C., Partridge, A., Dakhil, S., Garcia, A., Gralow, J., Lombard, J., Forbes, J., Martino, S., Barlow, W., Fabian, C., Minasian, L., Meyskens, F., Gelber, R., Hortobagyi, G., & Albain, K.. (2019). Final Analysis of the Prevention of Early Menopause Study (POEMS)/SWOG Intergroup S0230. JNCI: Journal of the National Cancer Institute. [Online] 111 (2), 210-213. Available from: [Accessed 4 October 2020].

  10. National Osteoporosis Foundation (2021) What Women Need To Know. [Online] Available from: [Accessed 20 July 2021].

  11. Society for Endocrinology (2018) Gonadotrophin-Releasing Hormone. [Online] Available from: [Accessed 4 October 2020].

  12. University College Hospitals London (2020) Medical Treatment For Endometriosis. [Online] Available from: {Accessed 4 October 2020].

  13. WebMD (2020) Zoladex Inplant. [Online] Available from: [Accessed 4 October 2020].


  1. Breast Cancer Org (2020) Zoladex Helps Preserve Fertility in Women With Early-Stage, Hormone-Receptor-Negative Breast Cancer Treated With Chemotherapy. [Online] Available from: [Accessed 4 October 2020].

  2. Cancer Research UK (2020) Goserelin (Zoladex) for Breast Cancer. [Online] Available from: [Accessed 4 October 2020]

  3. Medical News Today (2020) Zoladex (Goserelin) [Online] Available from: [Accessed 4 October 2020].

  4. National Institute for Health and Care Excellence (2020) Goserelin [Online] Available from: [Accessed 4 October 2020].

  5. TerSera Theraputics (2020) Prescribe Zoladex® For Your Appropriate Patients With Endometriosis. [Online] Available from: [Accessed 4 October 2020].

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Feb 23, 2021

Great piece- thank you, also have been on Zoladex for a while and found it beneficial. I felt like I should go hide in a corner for admitting to even using it- feeling reassured now. hoping you laparoscopy went well

The Endo Monologues
The Endo Monologues
Mar 04, 2021
Replying to

Thank you so much for your kind words. It's weird how ashamed we are made to feel when this treatment actually works for some individuals. Sending hugs.

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