Degarelix
Aliases: Firmagon
Last verified: 2026-09-23
The short version
A GnRH antagonist — immediate testosterone suppression without flare, for prostate cancer.
Identity & type
- Molecular type
- peptide
- Origin
- A GnRH antagonist — immediate testosterone suppression without flare, for prostate cancer.
Mechanism of action
Competitive GnRHR blockade → direct LH/FSH suppression.
Dosing & routes
Official / clinical context
Approved drug — indications, dosing and warnings are defined by the official label. 240 mg SC start, then 80 mg monthly.
Regulator-approved labeling and published study designs — never a recommendation.
Community-reported practice
240 mg SC start, then 80 mg monthly. Firmagon: fast testosterone suppression without the initial "flare" — an advantage oncologists and patients notice in prostate cancer.
Unverified self-reports. Not medical advice. Not endorsement.
Expected effects (community)
Firmagon: fast testosterone suppression without the initial "flare" — an advantage oncologists and patients notice in prostate cancer.
Protocol — official vs community
Official / label
Firmagon, for advanced prostate cancer with evidence of rising PSA and no symptomatic metastases (or per local label): starting dose 240 mg SC given as two consecutive 120 mg injections, then 80 mg SC every 28 days.
- 01Start: 240 mg (2 × 120 mg) on day 1
- 02Maintenance: 80 mg every 28 days, no further dose adjustment
Duration: Continuous while indicated; testosterone suppression is immediate and maintained while dosing continues.
A GnRH antagonist: blocks the receptor directly, so castrate-level testosterone is reached within days and without the initial flare that agonists require anti-androgen cover for. Injection-site reactions are the common price of the large SC volumes.
Community (anecdotal)
No gray-market self-use protocol; supervised GnRH-antagonist suppression also appears in gender-affirming care in some jurisdictions.
- Cycle:
- Set by the monthly injection schedule.
- Break:
- None — suppression reverses over weeks to months after stopping.
Community relevance is patient-level: the no-flare profile and monthly self-injection are the distinguishing talking points versus depot agonists in prostate-cancer forums.
Human evidence
Comparisons show faster PSA decline than agonists.
Preclinical evidence
The preclinical phase was completed and submitted to regulators as part of registration; pharmacology and toxicology details are part of the official label.
Known risks
- Injection-site reactions (common), hot flashes.characterized
Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.
Unknowns & evidence gaps
- Real-world data outside controlled trials