Goserelin (Zoladex)

Pronunciation: GOSS-er-eh-lin.

Generic name
goserelin (as goserelin acetate)
Drug class
Gonadotropin-releasing hormone (GnRH/LHRH) agonist
Form
Biodegradable cylindrical implant, 3.6 mg (every 28 days) or 10.8 mg (every 12 weeks, prostate cancer only), inserted via a purpose-designed applicator syringe
Route
Subcutaneous implant
Legal status
Prescription-only medicine in every market confirmed this session (United States, United Kingdom, European Union, Canada, Australia, New Zealand); always check your own country and product label.

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Zoladex (SAFESYSTEM) (5) · Full directory

What goserelin (as goserelin acetate) is and how it works

Goserelin is a gonadotropin-releasing hormone (GnRH) agonist, given as a small biodegradable implant placed just under the skin of the abdomen. Over time it suppresses the body's production of testosterone (in men) or oestrogen (in women), which is useful in certain hormone-sensitive cancers and gynaecological conditions. (1) (2) (4)

Goserelin's approved uses genuinely differ by country: every market checked covers prostate cancer, breast cancer, endometriosis, and endometrial thinning before a procedure, but the UK, Australian, and New Zealand labels additionally cover uterine fibroids and pituitary down-regulation for assisted reproduction, which the US and Canadian labels do not include. The single most important safety fact for anyone starting goserelin is the 'tumour flare' effect: before goserelin lowers your hormone levels, it first causes a brief, temporary RISE in testosterone or oestrogen, which can make cancer-related symptoms feel worse for the first few weeks -- including, in men with prostate cancer that has spread to the bones or spine, a real risk of spinal cord compression or urinary blockage that requires close monitoring during the first month.

Mechanism of action: how goserelin (as goserelin acetate) works

Goserelin is a synthetic decapeptide analogue of gonadotropin-releasing hormone (GnRH/LHRH). Continuous administration initially stimulates, then paradoxically suppresses, pituitary gonadotropin secretion, reducing testosterone (men) or oestradiol (women) to castrate/postmenopausal-equivalent levels after several weeks of treatment. (5)

What goserelin (as goserelin acetate) is used for

Prostate cancer

Used for hormone-dependent advanced or metastatic prostate cancer, and for locally advanced prostate cancer alongside radiotherapy or an anti-androgen medicine, or as adjuvant therapy after external beam radiation. (1) (4) (5)

Breast cancer

Used to treat advanced breast cancer, or as an alternative to chemotherapy for early breast cancer, in pre- and perimenopausal women whose tumour contains hormone receptors. (1) (2) (4)

Endometriosis

Used for pain relief and to reduce the size and number of endometriosis lesions, typically for up to six months. (1) (2) (4) (5)

Endometrial thinning before a procedure

Used to thin the lining of the womb before endometrial ablation for heavy or dysfunctional uterine bleeding. (1) (2) (4) (5)

Uterine fibroids (UK, Australia, New Zealand)

Used to shrink fibroids, reduce related symptoms including pain, and improve anaemia caused by heavy fibroid-related bleeding before surgery -- confirmed on the UK, Australian, and New Zealand labels reviewed for this dossier, but not on the US or Canadian labels checked. (2) (5) (6)

Assisted reproduction (UK, Australia, New Zealand)

Used to temporarily switch off the pituitary gland's own hormone signals before controlled ovarian stimulation for fertility treatment -- confirmed on the UK, Australian, and New Zealand labels reviewed for this dossier, but not on the US or Canadian labels checked. (2) (5) (6)

Before taking goserelin (as goserelin acetate)

Do not take / not appropriate for

  • Do not have a goserelin implant if you have a known hypersensitivity to GnRH, GnRH agonist analogues, or any component of the implant. (all countries) (1) (5)
  • Do not use goserelin during pregnancy, and it is not recommended during breastfeeding. Non-hormonal contraception should be used during treatment if pregnancy is possible. (all countries) (1) (4)
  • Women with undiagnosed abnormal vaginal bleeding should not start goserelin until this has been investigated. (Canada) (4)

Tell your clinician about

  • If you have prostate cancer that has spread to the bones or spine (vertebral metastases), or a history of urinary tract blockage -- you will need close monitoring during your first month of treatment.
  • If you have a low body mass index (BMI under 18.5) or are fully anticoagulated (on blood thinners) -- extra care is needed when the implant is inserted.
  • If you have diabetes, risk factors for diabetes, or heart disease, since goserelin can affect blood sugar control and cardiovascular risk.
  • If you have a history of long QT syndrome, congestive heart failure, or take other medicines that affect heart rhythm.
  • If you have risk factors for osteoporosis, such as a family history, smoking, or low calcium intake.
  • If you have depression or a history of mood disorders, since GnRH agonists can increase the risk of new or worsening depression.
  • Any other medicines you take.
(1) (2) (4) (5)

How to take goserelin (as goserelin acetate)

  • Goserelin is given as a small implant inserted just under the skin of the lower abdomen by a trained healthcare professional -- it is not a medicine you take yourself at home.
  • The 3.6 mg implant is given every 28 days; the 10.8 mg implant (prostate cancer only, where available) is given every 12 weeks.
  • Do not delay or miss your scheduled implant appointment, as your hormone levels may rise again if a dose is delayed.
  • For prostate cancer treated alongside radiotherapy, your prescriber may add a short course of an anti-androgen medicine beforehand to help prevent tumour flare.
  • Never attempt to remove, adjust, or manage your own implant or dosing schedule -- always follow your care team's instructions.
(1) (5)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

Contact your clinic as soon as possible to reschedule if you miss or are unable to attend a scheduled implant appointment -- do not wait until your next routine visit, since a delay can allow your hormone levels to rise again.

Overdose

This dossier's sources did not detail specific overdose symptoms or management for goserelin implants, given the controlled, clinician-administered dosing schedule. Contact your care team or seek urgent medical attention if you have concerns about receiving an incorrect dose.

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Hot flushes/hot flashes.

What to notice: Hot flushes/hot flashes.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Sweating (hyperhidrosis).

What to notice: Sweating (hyperhidrosis).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Decreased libido / sexual dysfunction, including erectile dysfunction.

What to notice: Decreased libido / sexual dysfunction, including erectile dysfunction.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Injection site reactions.

What to notice: Injection site reactions.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Bone pain.

What to notice: Bone pain.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Breast swelling/tenderness in men (gynaecomastia).

What to notice: Breast swelling/tenderness in men (gynaecomastia).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Weakness/fatigue (asthenia).

What to notice: Weakness/fatigue (asthenia).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Lower urinary tract symptoms.

What to notice: Lower urinary tract symptoms.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Tumour flare -- temporary worsening of symptoms when starting treatment — canada_serious_warnings_box; high caution elsewhere

Symptoms: New or worsening bone pain, difficulty passing urine, or new weakness/numbness, usually within the first few weeks of starting treatment.

Action: This is expected and usually temporary, caused by a brief initial rise in testosterone or oestrogen before goserelin's suppressive effect takes hold. Tell your care team promptly about any new or worsening symptoms so they can monitor you closely and manage symptoms if needed -- this is confirmed as a real, well-documented effect across every market checked (US, UK, France/EU, Canada, Australia, New Zealand). (1) (2) (4) (5)

Spinal cord compression (men with prostate cancer that has spread to the spine) — high caution

Symptoms: New weakness, numbness, or tingling in the legs, or loss of bladder or bowel control.

Action: Seek urgent medical attention immediately -- this is a medical emergency. If you have prostate cancer that has spread to the spine, your care team will monitor you closely during your first month of treatment because of this risk. (1) (2) (4) (5)

Urinary tract/ureteric obstruction (men with a history of urinary blockage) — high caution

Symptoms: Difficulty or inability to pass urine, reduced urine output, or flank/back pain.

Action: Seek urgent medical attention -- this can lead to kidney damage if untreated. Your care team will monitor you closely during your first month of treatment if you have a history of this problem. (1) (2) (4) (5)

Injection site or vascular injury — canada_serious_warnings_box; high caution elsewhere

Symptoms: Severe pain, swelling, bruising, or bleeding at the implant site, or signs of internal bleeding (light-headedness, abdominal pain).

Action: Seek urgent medical attention for severe or worsening symptoms. Your implant will be given by a healthcare professional experienced in this procedure; tell them if you have a low body weight or take blood-thinning medicines. (1) (4) (5)

Heart rhythm changes (QT prolongation) — important safety information

Symptoms: Palpitations, dizziness, or fainting.

Action: Tell your prescriber if you have a history of heart rhythm problems, since goserelin (like other androgen deprivation therapy) may prolong the QT interval on an ECG; your prescriber will weigh the benefits and risks and may monitor your heart rhythm. (1) (2) (4) (5)

New or worsening high blood sugar / diabetes — moderate caution

Symptoms: Increased thirst, frequent urination, or fatigue.

Action: Your prescriber may monitor your blood sugar periodically, especially if you already have diabetes or risk factors for it. (1) (2) (5)

Heart attack, stroke, or cardiac risk — moderate caution

Symptoms: Chest pain, shortness of breath, sudden weakness, or difficulty speaking.

Action: Seek emergency medical attention for these symptoms. Men on GnRH agonist therapy have an increased reported risk of myocardial infarction, sudden cardiac death, and stroke; your prescriber will consider your individual cardiovascular risk factors. (1) (2) (5)

Loss of bone density — moderate caution

Symptoms: Usually no symptoms until a fracture occurs.

Action: Tell your prescriber about any osteoporosis risk factors. Bone density loss (around 6-11% over 2 years in some reported cases) is partially reversible after stopping treatment; your prescriber may recommend monitoring or bone-protective measures for longer courses. (2) (5) (4)

New or worsening depression — important safety information

Symptoms: Persistent low mood, loss of interest in activities, or thoughts of self-harm.

Action: Tell your prescriber promptly about any mood changes -- GnRH agonists have been associated with an increased risk of depression, which may be severe. (2)

Interactions

  • Medicines that affect heart rhythm (QT-prolonging drugs): tell your prescriber about all other medicines you take, since combined use may increase the risk of heart rhythm problems. (1) (4)
  • Anticoagulant (blood-thinning) medicines: tell your care team, since this affects the safety of implant insertion. (4) (5)
  • Fertility medicines (gonadotrophins), if goserelin is used for assisted reproduction: your specialist will monitor closely for ovarian hyperstimulation syndrome. (5)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Goserelin must not be used during pregnancy. Pregnancy should be excluded before starting treatment, and non-hormonal contraception should be used during therapy if pregnancy is possible. (1) (2) (3) (4) (5) (6)

Children

Not indicated for use in children; safety and effectiveness in children have not been established. (1) (2) (3) (4) (5) (6)

Elderly

No dosage adjustment is necessary in the elderly, per the Australian and New Zealand labels reviewed. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

No dosage adjustment is necessary for patients with hepatic impairment, per the Australian and New Zealand labels reviewed. (1) (2) (3) (4) (5) (6)

Renal_impairment

No dosage adjustment is necessary for patients with renal impairment, per the Australian and New Zealand labels reviewed. (1) (2) (3) (4) (5) (6)

Source_ids

US-DAILYMED-ZOLADEX-36-2026,AU-TGA-ZOLADEX-PI-2026,NZ-MEDSAFE-GOSERELIN-TEVA-2026 (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Pregnancy test where relevant.
  • Assessment of prostate cancer metastasis pattern (spine, urinary tract) to identify tumour-flare risk.
  • Cardiovascular risk factors and baseline ECG if you have risk factors for QT prolongation.
  • Bone density risk factors, especially for longer courses of treatment for benign conditions.

During treatment

  • Close monitoring during the first month of therapy for signs of tumour flare, spinal cord compression, or urinary obstruction, especially in men with metastatic prostate cancer.
  • Periodic blood glucose monitoring if you have diabetes or risk factors for it.
  • Attend every scheduled implant appointment on time -- do not delay.
(1) (4) (5)

Storage

Store at room temperature as directed on the packaging; use the implant immediately after opening the sterile pouch, and do not use if the pouch is damaged.

Professional information

Clinician-facing context only, sourced from the current US DailyMed prescribing information, UK EMC SmPC, France's ANSM database, Health Canada product monograph, Australia's TGA-approved PI, and New Zealand's Medsafe data sheet reviewed for this dossier; verify against the current full label for the specific product before prescribing.

United States, Canada

Indication: Prostate cancer, breast cancer, endometriosis, endometrial thinning (narrower indication set; no uterine fibroids or assisted reproduction)

Dose summary: 3.6 mg SC implant every 28 days; 10.8 mg SC implant every 12 weeks (US, prostate cancer only).

Renal context: Sources reviewed for this dossier did not detail US/Canada-specific renal dosing guidance beyond the general absence of a required adjustment noted on the Australian/NZ labels. (1) (4)

United Kingdom, Australia, New Zealand

Indication: Broadest indication set: adds uterine fibroids and assisted-reproduction pituitary down-regulation

Dose summary: 3.6 mg SC implant every 28 days; benign gynaecological conditions typically limited to 6 months without a bone-density risk assessment.

Renal context: No dosage adjustment necessary for renal or hepatic impairment, or in the elderly. (2) (5) (6)

Mechanism of action

Hepatic guidance

No dosage adjustment necessary for patients with hepatic impairment, per the Australian and New Zealand labels reviewed.

Overdose note

Sources reviewed for this dossier did not detail specific overdose management guidance for goserelin implants. (5)

Frequently asked questions

Is Zoladex/goserelin available in the US, UK, EU, Canada, Australia, and New Zealand?

Yes, confirmed authorised via direct regulator sources in all six markets: the United States (DailyMed), United Kingdom (EMC SmPC), the European Union (France's ANSM database, since Zoladex's authorisation predates the EMA's centralised procedure), Canada (Health Canada product monograph), Australia (TGA ARTG), and New Zealand (Medsafe, Teva brand). (1) (2) (3) (4) (5) (6)

Why might my symptoms feel worse in the first few weeks of goserelin treatment?

This is called 'tumour flare.' Goserelin works by lowering testosterone or oestrogen, but it causes a brief initial RISE in these hormones before its suppressive effect takes hold, which can temporarily worsen cancer-related symptoms during the first few weeks. In men with prostate cancer that has spread to the bones or spine, this can occasionally include a real risk of spinal cord compression or urinary tract blockage, which is why close monitoring during the first month of treatment is important. (1) (2) (4) (5)

Does goserelin carry a boxed warning?

Not in the United States -- there is no boxed warning on the current US FDA label. Health Canada's product monograph, however, carries a formal 'Serious Warnings and Precautions' section covering tumour flare reaction, osteoporosis, and injection-site/vascular injury, which is Canada's own equivalent of a boxed warning. (1) (4)

Is goserelin approved for the same uses everywhere?

No. The US and Canadian labels cover prostate cancer, breast cancer, endometriosis, and endometrial thinning. The UK, Australian, and New Zealand labels additionally cover uterine fibroids and pituitary down-regulation before assisted-reproduction treatment. (1) (4) (2) (5) (6)

What is the mechanism of action of goserelin (as goserelin acetate)?

Goserelin is a synthetic decapeptide analogue of gonadotropin-releasing hormone (GnRH/LHRH). Continuous administration initially stimulates, then paradoxically suppresses, pituitary gonadotropin secretion, reducing testosterone (men) or oestradiol (women) to castrate/postmenopausal-equivalent levels after several weeks of treatment. (5)

What is the generic name of Goserelin (Zoladex)?

The generic name is goserelin (as goserelin acetate). (1) (5)

What class of drug is goserelin (as goserelin acetate)?

Goserelin (Zoladex) is classed as: Gonadotropin-releasing hormone (GnRH/LHRH) agonist. (1) (5)

References

  1. ZOLADEX (goserelin acetate implant) 3.6 mg -- full prescribing informationDailyMed (U.S. National Library of Medicine) -- FDA-approved prescribing information · United States · dated 2025-01-01 · accessed 2026-07-31 · source 1
  2. Zoladex 3.6mg Implant -- SmPCelectronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · dated 2025-01-01 · accessed 2026-07-31 · source 2
  3. ZOLADEX 3,6 mg, implant en seringue prereplie pour voie sous-cutanee -- medicine extractBase de Donnees Publique des Medicaments (ANSM / French Ministry of Health) -- official French medicines database · European Union (France) · dated 1987-01-26 · accessed 2026-07-31 · source 3
  4. ZOLADEX (goserelin acetate) 3.6 mg Depot -- Product Monograph, Submission Control No. 210199Health Canada -- Product Monograph (TerSera Therapeutics / AstraZeneca Canada) · Canada · dated 2017-12-21 · accessed 2026-07-31 · source 4
  5. ZOLADEX (goserelin 3.6mg implant) -- Australian Product InformationTherapeutic Goods Administration (TGA), Australia -- ARTG entry and approved Product Information · Australia · dated 1991-10-14 · accessed 2026-07-31 · source 5
  6. Goserelin (Teva) 3.6 mg implant -- New Zealand Data Sheet, Version 1.2Medsafe (New Zealand Medicines and Medical Devices Safety Authority) · New Zealand · accessed 2026-07-31 · source 6

Brand names by country

Single-ingredient goserelin (as goserelin acetate) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • ZOLADEX10.8 mg, 3.6 mg · tersera therapeutics llc

United Kingdom

  • Zoladex / Zoladex LA (2)MHRA licensed confirmed · 3.6 mg, 10.8 mg (LA) · AstraZeneca UK Limited

Canada

  • ZOLADEX INJ DEPOT
  • ZOLADEX LA INJ DEPOT

Australia

  • Zoladex (SAFESYSTEM) (5)TGA ARTG registered confirmed 24368 · 3.6 mg · AstraZeneca Pty Ltd

New Zealand

  • Goserelin (Teva) (6)Medsafe listed confirmed · 3.6 mg · Teva Pharmaceuticals
View brands in additional countries.

European Union

Zoladex (3)

This page provides general reference information about goserelin (Zoladex) and is not a substitute for advice from your pharmacist or clinician. Goserelin is given by a healthcare professional on a fixed schedule -- never attempt to manage your own dosing. Seek urgent medical attention for new weakness, numbness, or difficulty passing urine, especially in the first month of treatment.

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