Zoladex (Goserelin)
A tiny implant injected under the skin of the tummy that switches off the ovaries or testes for 1 or 3 months at a time. Powerful, reversible, and comes with a menopause-like package.
Quick answer: Zoladex (goserelin) is an implant given into the skin of the tummy every 4 weeks (3.6 mg) or 12 weeks (10.8 mg). After an initial short surge, it shuts down oestrogen or testosterone. It treats prostate and breast cancer, endometriosis, and shrinks fibroids before surgery. Side effects come from low hormones: hot flushes, sweats, low libido, mood changes, vaginal dryness and bone thinning with longer use.
At a glance
- For
- Prostate cancer, breast cancer, endometriosis, fibroids before surgery, IVF
- Works
- Reliably switches off sex hormones within 3–4 weeks
- Cost
- $25 a script on the PBS for approved uses ($7.70 concession)
- Kicks in
- Hormones surge for about a week, then drop by 3–4 weeks
- Dose
- 3.6 mg every 28 days or 10.8 mg every 12 weeks; endometriosis courses are usually up to 6 months
- Watch for
- Hot flushes, sweats, low libido, mood changes, headache, vaginal dryness, bone thinning
A medical menopause (or andropause) on demand. Effective, but plan the bone and mood protection before the first dose.
Brand names
- Zoladex 3.6 mg (monthly) and Zoladex LA 10.8 mg (3-monthly) implants
How it works
Goserelin is a copy of GnRH, the brain hormone that tells the pituitary to switch on the ovaries or testes. Given continuously instead of in pulses, it first overstimulates, then switches the system off, so oestrogen or testosterone drops to menopausal or castrate levels.
Used for
- Prostate cancer: advanced or high-risk, often with radiotherapy (TGA-approved)
- Breast cancer: hormone-sensitive, in women before menopause (TGA-approved)
- Endometriosis: pain relief, usually for up to 6 months, often with add-back hormone therapy (TGA-approved)
- Fibroids: shrinking them and correcting anaemia before surgery (TGA-approved)
- IVF: suppressing natural cycles before stimulation
Side effects
Nearly everyone gets low-hormone effects: hot flushes and sweats are very common, plus lower libido, mood changes and headaches. Women get vaginal dryness and periods stop; men may get erection problems and breast swelling. Longer courses thin the bones. In prostate cancer, symptoms can briefly flare in the first weeks.
Full side-effect list (from the product information)
How often, from the official product information. Bold = serious.
Very common more than 1 in 10
- Hot flushes and sweating
- Lower libido
- Erection problems (men)
- Vaginal dryness, breast size change (women)
- Acne or skin reactions
Common 1 in 10 to 1 in 100
- Low mood or mood swings
- Headache
- Pins and needles
- Bone thinning and joint pain
- Weight gain
- Injection-site pain or bruising
- Breast swelling or tenderness (men)
- Raised blood pressure
- Raised blood sugar, heart risk (men on long-term treatment)
- Tumour flare in prostate cancer (bone pain, urine trouble) in the first weeks
Uncommon 1 in 100 to 1 in 1,000
- Allergic reactions
- Raised calcium (breast cancer with bone spread)
Rare 1 in 1,000 to 1 in 10,000
- Pituitary bleeding (sudden headache, vision loss)
- Ovarian cysts
- Low blood pressure, injection-site bleeding
- Spinal cord compression from flare in prostate cancer with spine spread
Get help urgently if
- Sudden severe headache with vomiting or vision loss
- New back pain with leg weakness, numbness or bladder problems (prostate cancer). Call 000
- Heavy bleeding or a growing lump at the injection site
- Low mood with thoughts of self-harm. Call Lifeline 13 11 14
Good to know
- Bones: for courses longer than a few months, ask about calcium, vitamin D, exercise and a bone density scan.
- Add-back HRT (a little oestrogen and progestogen) for endometriosis reduces flushes and bone loss without undoing the benefit.
- Contraception: periods usually stop, but use a non-hormonal method; it’s not a contraceptive and harms pregnancy.
- Prostate cancer: an anti-androgen tablet is often given for the first weeks to block the flare. Men on long-term treatment need heart, sugar and bone checks.
- Effects wear off over a few months after the last implant.
Common questions
What is Zoladex used for?
Prostate cancer, hormone-sensitive breast cancer before menopause, endometriosis, shrinking fibroids before surgery, and IVF. It switches off the body’s sex hormones.
What are the side effects of Zoladex?
Mostly menopause-like effects from low hormones: hot flushes, sweats, low libido, mood changes, headaches, vaginal dryness and, over longer courses, bone thinning. Men may have erection problems and breast swelling.
Is Zoladex a contraceptive?
No. Periods usually stop, but you should still use a non-hormonal contraceptive, because pregnancy is possible early on and the medicine can harm a pregnancy.
Information only. Not a recommendation or endorsement of any product. Whether a medicine suits you depends on your health and other medicines, so talk to your doctor or pharmacist. In an emergency, call 000 (Australia) or your local emergency number. From a mobile, 112 works in most countries.
More information
maladywise.com/medicines/goserelin/