Short answer: Zoladex 3.6 mg is one implant injected under the skin of the front of the belly, below the navel, every 28 days under a physician's supervision. For endometriosis the course is 6 months. Before endometrial ablation it is one or two implants four weeks apart. For advanced prostate and breast cancer it is long-term. The label says a delay of a few days is permissible.
This is what the FDA label says. Follow your prescriber. Your prescriber may use a different dose or pace than the label's standard schedule.
What Zoladex 3.6 mg is approved for: Zoladex 3.6 mg is a GnRH agonist approved, with flutamide, for locally confined stage B2-C prostate cancer; for palliative treatment of advanced prostate cancer; for endometriosis; for thinning the uterine lining before endometrial ablation for dysfunctional uterine bleeding; and for palliative treatment of advanced breast cancer in pre- and perimenopausal women (sections 1.1 to 1.5). The 10.8 mg 3-month implant is a separate label.
Source
ZOLADEX (goserelin implant) 3.6 mg, for subcutaneous use, prescribing information. TerSera Therapeutics. DailyMed, version published March 26, 2026. DailyMed setid 294b168b-6e5f-4db9-bf70-d599271458b3
Zoladex 3.6 mg is a small biodegradable cylinder containing goserelin, preloaded in a single-use syringe with a 16-gauge needle and a protective sleeve. It releases drug continuously over 28 days (sections 3 and 11).
It is injected under the skin of the front abdominal wall below the navel line at a 30 to 45 degree angle, using aseptic technique, under a physician's supervision. It does not go into muscle or the abdominal cavity, and the syringe cannot be used to aspirate (sections 2 and 2.7).
If a large blood vessel is hit, blood appears in the syringe at once; the needle is withdrawn, a new syringe is used elsewhere, and the person is watched for signs of abdominal bleeding (section 2.7).
The table below is the label's schedule, from the Dosage and Administration section. Numbers are copied exactly; the section is in brackets.
| Use | Schedule | Length |
|---|---|---|
| All uses | 3.6 mg subcutaneously every 28 days | See below |
| Stage B2-C prostate cancer (with flutamide and radiation) | Start 8 weeks before radiotherapy: one 3.6 mg depot then the 10.8 mg depot 28 days later, or four 3.6 mg depots at 28-day intervals (two before and two during radiotherapy) | Continues during radiation therapy |
| Advanced prostate cancer | 3.6 mg every 28 days | Long-term unless clinically inappropriate |
| Endometriosis | 3.6 mg every 28 days | 6 months |
| Endometrial thinning before ablation | One or two depots, four weeks apart | Surgery at four weeks after one depot, or two to four weeks after the second depot |
| Advanced breast cancer | 3.6 mg every 28 days | Long-term unless clinically inappropriate |
Retreatment for endometriosis cannot be recommended because safety data are not available. If further treatment is considered, bone density monitoring is considered. Adding estrogen and/or progestin hormone therapy reduced bone loss and hot flushes in studies.
No dose adjustment is needed for kidney or liver impairment.
In men, testosterone falls to castrate levels about 2 to 4 weeks after starting. In women, estradiol falls to postmenopausal levels within 3 weeks.
Tests of pituitary and sex-hormone function may be misleading during treatment and until periods return. Normal function usually returns within 12 weeks after stopping.
In endometriosis studies, periods stopped in 92% and 80% of women within 8 weeks, and usually returned within 8 weeks after the course ended.
Stored at room temperature, not above 25 C (77 F).
While a delay of a few days is permissible, every effort should be made to adhere to the 28-day schedule. The patient counseling section adds that women who miss one or more successive doses may have breakthrough menstrual bleeding (section 17.3). The label gives no other missed-dose rule.
More on this: missed a dose of Zoladex 3.6 mg.
For stage B2-C prostate cancer, the label allows one 3.6 mg depot followed 28 days later by the 10.8 mg depot. The 10.8 mg implant has its own separate label.
In Dose Track you set up Zoladex 3.6 mg as a protocol with the dose and schedule your prescriber gave you. A protocol can hold dose steps, each with its own dose and length in days or weeks, so a step-up plan like the one on the label can be entered once and the app moves to the next step on its own. Reminders follow the schedule, and every dose is logged with the date and time, so you can see which step you are on and when your last dose was. The app follows what you enter; it does not choose or change a dose.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.