Degarelix (Firmagon)

How Medicare covers it

Part B (injection given by a clinician — see the Part B basis in this package; the usual path for this drug). The Part D aggregation in this package is carried exactly as computed — the formulary file carries the injection concepts. Part A during a covered inpatient stay.

What it treats

Firmagon (degarelix) treats patients with advanced prostate cancer. It is a hormone therapy that lowers testosterone, the male hormone that prostate cancer needs to grow.

What it is for, in depth

Firmagon is a hormone (androgen deprivation) therapy for men with advanced prostate cancer. Prostate cancer cells need testosterone to grow, and Firmagon shuts down testosterone production quickly by blocking GnRH receptors in the pituitary gland, without the temporary testosterone flare that GnRH agonist drugs can cause at the start. It is given in a medical office as an injection under the skin of the abdomen: a one-time starting dose of 240 mg (two 120 mg injections), then a single 80 mg injection every 28 days. Treatment effect is followed with periodic PSA blood tests. The most common problems are reactions where the shot is given and hot flashes, and the label warns about severe allergic reactions, QT interval prolongation of the heart rhythm, and harm to an unborn baby.

How it works

Degarelix is a gonadotropin-releasing hormone (GnRH) receptor antagonist. It binds reversibly to GnRH receptors in the pituitary gland, which reduces the release of the gonadotropin hormones (LH and FSH) and, as a result, lowers testosterone. A single 240 mg dose lowers LH, FSH, and then testosterone, and Firmagon keeps testosterone suppressed below the castration level of 50 ng/dL. Unlike GnRH agonists, it does not cause an initial testosterone surge.

How it is taken

Firmagon is given by a healthcare professional only, as an injection under the skin (subcutaneous) in the abdomen, in an area not exposed to pressure from a waistband or belt and not close to the ribs. The starting dose is 240 mg, given as two injections of 120 mg each. Starting 28 days later, the maintenance dose is 80 mg given as a single injection once every 28 days. The injection site should be varied regularly. Firmagon comes as a powder in single-dose vials (120 mg and 80 mg) that is mixed with sterile water before injection, and the mixed drug must be used within one hour.

Common side effects

The most common side effects (10% or more) are injection site reactions (pain, redness, swelling, or hardness at the injection site, in 35% of patients), hot flashes (26%), weight increase (9%), and increases in liver enzymes (transaminases and GGT, 10%). Other effects in 5% or more of patients included hypertension (6%), back pain (6%), constipation (5%), joint pain (5%), chills (5%), and urinary tract infection (5%). Effects in 1% to less than 5% included weakness, fatigue, fever, night sweats, nausea, dizziness, headache, and insomnia, and erectile dysfunction, testicle shrinkage, and breast enlargement (gynecomastia) occurred in 1% or more.

Serious warnings

Serious allergic (hypersensitivity) reactions, including anaphylaxis, hives (urticaria), and angioedema (swelling under the skin), have been reported with Firmagon; if a severe reaction occurs, the drug must be stopped at once and the patient must not be given Firmagon again. Androgen deprivation therapy such as Firmagon may prolong the QT interval of the heart, so the benefits should be weighed against the risks in patients with congenital long QT syndrome, heart failure, frequent electrolyte abnormalities, or use of other drugs that prolong the QT interval, and ECGs and electrolytes should be checked from time to time. Firmagon can cause fetal harm and loss of pregnancy, so it is not for use in women who are pregnant. Because Firmagon suppresses the pituitary-gonadal system, it affects pituitary and gonadal function test results, and its effect should be followed by measuring PSA periodically.

Who should be careful

Firmagon must not be used in patients with a history of a severe allergic reaction to degarelix or any of its components, and patients who have had such a reaction should not be re-challenged. Tell your doctor if you have congenital long QT syndrome, heart failure, or abnormal blood electrolytes (these should be corrected), or if you take medicines that prolong the QT interval. Firmagon is for men with advanced prostate cancer; based on animal studies it can cause fetal harm and pregnancy loss, and it is not intended for women. Liver enzyme increases occur, and PSA and, if PSA rises, testosterone levels should be monitored during treatment.

Major interactions

No drug-drug interaction studies have been conducted with Firmagon. Degarelix is not processed by the human CYP450 enzyme system and does not induce or inhibit CYP450 enzymes in laboratory studies, so clinically important CYP450-related drug interactions are unlikely. Even so, because androgen deprivation therapy can prolong the QT interval, care is needed in patients taking other drugs known to prolong the QT interval.

Cost and saving notes

If this drug is covered under your Medicare Part D plan and the cost is high, you can ask your plan for a tier exception to pay a lower cost share. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower your Part D premiums and drug costs. In 2027, your total yearly out-of-pocket spending on covered Part D drugs is capped at $2,400, and you can spread those costs out in monthly payments through the Medicare Prescription Payment Plan.

Why it is in its tier

Degarelix (Firmagon) sits on Tier 4 in 88.54% of the plans that list it (4753 of 5368 listing plans). Tier 4 is the non-preferred tier — higher copays or coinsurance. The data-visible drivers: It is a brand-only product with no generic version in the formulary data, and the CMS dashboard puts its average Part D spending at about $2,718 per beneficiary for 2024 — a mid-cost drug, which matches where plans place it. It is listed by 97.69% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• FIRMAGON (DEGARELIX) KIT [FERRING PHARMACEUTICALS INC.] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus — Degarelix Injection

What official patient guides say

In daily life, this treatment does not add a daily task at home. A doctor or nurse gives it as a shot under the skin of your stomach, away from your ribs and waistline, once every 28 days at a medical facility, so keeping that monthly appointment is the main routine. After each shot, make sure your belt or waistband does not press on the spot where the medicine went in, since the area can be sore, red, or swollen for a while. Hot flashes, sweating or night sweats, tiredness, and some weight change are common while on this treatment. There is nothing to store at home, because the clinic handles the medicine. If you miss an appointment for a dose, call your doctor right away to reschedule. Keep all of your follow-up and lab appointments too, since your doctor will check how your body is responding to the treatment over time.

Source: MedlinePlus — Degarelix Injection

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 5,368 list Degarelix (Firmagon) — 97.7% of plans. Most of those plans put it on Tier 4: 4,753 plans, 88.5% of the plans that list it. Other plans place it on Tier 3 (497 plans), Tier 1 (114 plans) or Tier 2 (4 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 4; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 4; Aetna Medicare Value Plus (PPO) puts it on Tier 4. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.