Prescription medicine
Belzutifan Brand names: Welireg
Belzutifan (Welireg) is a prescription medicine with an FDA approval on record since 2021. No generic is listed in FDA's NDC Directory.
- No generic listed
- Boxed warning
Check it at the source: the belzutifan FDA label on DailyMed (effective June 12, 2026, Merck Sharp & Dohme LLC); the NDA 215383 record on Drugs@FDA; every belzutifan label on DailyMed.
Highlights of the record
FDA label of June 12, 2026; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026
EMBRYO-FETAL TOXICITY.
Exposure to WELIREG during pregnancy can cause embryo-fetal harm. Verify pregnancy status prior to the initiation of WELIREG. Advise patients of these risks and the need for effective non-hormonal contraception. WELIREG can render some hormonal contraceptives ineffective [see Warnings and Precautions (5.3), Drug Interactions (7.2), Use in Specific Populations (8.1 , 8.3) ]. WARNING: EMBRYO-FETAL TOXICITY See full prescribing information for complete boxed warning. Exposure to WELIREG during pregnancy can cause embryo-fetal harm. Verify pregnancy status prior to the initiation of WELIREG. Advise patients of these risks and the need for effective non-hormonal contraception. WELIREG can render some hormonal contraceptives ineffective.
Used for
From the label: indications and usageWELIREG is a hypoxia-inducible factor inhibitor indicated: von Hippel-Lindau (VHL) disease for treatment of adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery.
Forms and strengths
- 40 mg
Film-coated tablet.
On the market
- Earliest approval on file
- August 13, 2021 Welireg, Merck Sharp Dohme; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- No generic approved
- Labelers listed (NDC)
- 1 of which 0 under generic applications, 1 under brand applications, repackagers included
- Last listed patent
- June 30, 2042 Welireg tablets; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- Not in the survey
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- No recall recorded
- FAERS reports
- 1,573 through July 30, 2026
What is belzutifan used for?
From the label: indications and usageWELIREG is a hypoxia-inducible factor inhibitor indicated: von Hippel-Lindau (VHL) disease for treatment of adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery. ( 1.1 ) Renal Cell Carcinoma with a Clear Cell Component (ccRCC) in combination with pembrolizumab or pembrolizumab and berahyaluronidase alfa-pmph, for the adjuvant treatment of adult patients with ccRCC at intermediate-high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions. […]
FDA pharmacologic class: Hypoxia-inducible Factor Inhibitor.
Source: FDA drug label (WELIREG), Merck Sharp & Dohme LLC, effective June 12, 2026 (SPL set 13e15ee0-d679-4fa9-9430-e2e2170474da), via openFDA; the full label on DailyMed
What does the patient leaflet for belzutifan say first?
The FDA-approved Medication Guide or Patient Information that comes with the medicine, in its own words.
From the patient leaflet: What is the most important information I should know about WELIREG?WELIREG can cause serious side effects, including: Low red blood cell counts (anemia). Low red blood cell counts can be severe. You may need a blood transfusion if your red blood cell counts drop too low. Your healthcare provider will do blood tests to check your red blood cell counts before you start and during treatment with WELIREG. Tell your healthcare provider if you get any symptoms of low red blood cell counts, including tiredness, feeling cold, shortness of breath, chest pain, or fast heartbeat. Low oxygen levels in your body. WELIREG can cause low oxygen levels in your body that can be severe and may require you to stop treatment with WELIREG, receive oxygen therapy, or be hospitalized. Your healthcare provider will monitor your oxygen levels before you start and during treatment with WELIREG. Tell your healthcare provider or get medical help right away if you get symptoms of low oxygen in your body, including shortness of breath or increased heart rate. Harm to your unborn baby. Treatment with WELIREG during pregnancy can cause harm to your unborn baby. Females who are able to become pregnant: Your healthcare provider will do a pregnancy test before you start treatment with WELIREG. You should use an effective form of non-hormonal birth control (contraception) during treatment with WELIREG and for 1 week after your last dose. Birth control methods that contain hormones (such as birth control pills, injections, or transdermal system patches) may not work as well during treatment with WELIREG. Talk to your healthcare provider about birth control methods that may be right for you during treatment with WELIREG. Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with WELIREG. […]
From the patient leaflet: How should I store WELIREG?Store WELIREG at room temperature between 68°F to 77°F (20°C to 25°C). The WELIREG bottle has a child-resistant closure. The WELIREG bottle contains 2 desiccant canisters that help keep your medicine dry. Do not eat the desiccant canisters. Keep WELIREG and all medicines out of the reach of children.
Source: FDA drug label (WELIREG), Merck Sharp & Dohme LLC, effective June 12, 2026 (SPL set 13e15ee0-d679-4fa9-9430-e2e2170474da), via openFDA; the full label on DailyMed
Is there a generic for belzutifan (Welireg)?
No generic belzutifan is approved (Drugs@FDA, October 8, 2026).
The Orange Book lists 4 patents for Welireg tablets: the compound patent runs to September 5, 2034, and the last listed entry to June 30, 2042. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 2021 earliest approval on file
- 2042 last listed patent
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
What do FAERS reports show for belzutifan?
The FDA Adverse Event Reporting System holds 1,573 reports that list belzutifan among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 150 are coded as a death and 678 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What next?
- Belzutifan side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other