Belzutifan: uses, dosing, side effects & brands
Belzutifan is a medicine sold in the U.S. under one brand, for von hippel-lindau disease. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Treats
- Von Hippel-Lindau Disease
- Available as
- Tablet
- Sold as
- Welireg
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- Boxed warning
- Boxed warning
How belzutifan is dosed
From the FDA label for Welireg (application NDA215383). Other belzutifan products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
The recommended dosage of WELIREG in adult patients is 120 mg administered orally once daily with or without food. ( 2.1 ) The recommended dosage of WELIREG in pediatric patients 12 years and older is based on bodyweight: Patients weighing 40 kg or greater: 120 mg orally once daily Patients weighing less than 40 kg: 80 mg orally once daily 2.1 Recommended Dosage The recommended dosages for WELIREG are listed in Table 1. Table 1: Recommended Dosage Indication Recommended WELIREG Dosage Duration of Therapy von Hippel-Lindau Disease 120 mg orally once daily. Until disease progression or unacceptable toxicity. Adjuvant Treatment of ccRCC 120 mg orally once daily in combination with pembrolizumab or pembrolizumab and berahyaluronidase alfa-pmph. For the recommended dosage of pembrolizumab or pembrolizumab and berahyaluronidase alfa-pmph, refer to the respective Prescribing Information. Until disease recurrence or unacceptable toxicity, or up to 54 weeks. Treatment of Advanced ccRCC 120 mg orally once daily. Until disease progression or unacceptable toxicity. Pheochromocytoma or Paraganglioma Adults: 120 mg orally once daily. Pediatric patients 12 years and older based on bodyweight: Patients weighing 40 kg or greater: 120 mg orally once daily. Patients weighing less than 40 kg: 80 mg orally once daily. Until disease progression or unacceptable toxicity. Administration Instructions…
Belzutifan side effects
The following clinically significant adverse reactions are discussed elsewhere in the labeling: Anemia [see Warnings and Precautions (5.1) ] Hypoxia [see Warnings and Precautions (5.2) ] VHL disease : Most common (≥25%) adverse reactions, including laboratory abnormalities, were decreased hemoglobin, fatigue, increased creatinine, headache, dizziness, increased glucose, and nausea. ( 6.1 ) ccRCC : Most common (≥25%) adverse reactions for WELIREG, including laboratory abnormalities, in combination with pembrolizumab were decreased hemoglobin, increased alanine aminotransferase (ALT), fatigue, increased aspartate aminotransferase (AST), decreased lymphocytes, and increased alkaline phosphatase. ( 6.1 ) Most common (≥25%) adverse reactions for WELIREG as monotherapy, including laboratory abnormalities were decreased hemoglobin, fatigue, musculoskeletal pain, increased creatinine, decreased lymphocytes, increased ALT, decreased sodium, increased potassium, and increased AST. ( 6.1 ) PPGL : Most common (≥25%) adverse reactions, including laboratory abnormalities were anemia, fatigue, musculoskeletal pain, decreased lymphocytes, increased ALT, increased AST, increased calcium, dyspnea, increased potassium, decreased leukocytes, headache, increased alkaline phosphatase, dizziness, and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Merck Sharp & Dohme LLC at…
Who shouldn’t take belzutifan
None. None. ( 4 )
Belzutifan drug interactions
UGT2B17 or CYP2C19 Inhibitors: Monitor for signs and symptoms of anemia and hypoxia and reduce the dosage of WELIREG as recommended. ( 2.2 , 7.1 ) Sensitive CYP3A4 Substrates : Avoid coadministration with WELIREG for which minimal decrease in concentration may lead to reduced efficacy of the substrate. ( 7.2 ) 7.1 Effects of Other Drugs on WELIREG UGT2B17 or CYP2C19 Inhibitors Monitor for anemia and hypoxia and reduce the dosage of WELIREG as recommended [see Dosage and Administration (2.2) , Warnings and Precautions (5.1 , 5.2) , Adverse Reactions (6) ] . Coadministration of WELIREG with inhibitors of UGT2B17 or CYP2C19 increases belzutifan exposure [see Clinical Pharmacology (12.3 , 12.5) ] , which may increase the risk of adverse reactions of WELIREG. 7.2 Effect of WELIREG on Other Drugs CYP3A4 Substrates Avoid coadministration of WELIREG with sensitive CYP3A4 substrates, for which minimal decrease in concentration may lead to therapeutic failures of the substrate. If coadministration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in accordance with its Prescribing Information. Coadministration of WELIREG with CYP3A4 substrates decreases concentrations of CYP3A substrates [see Clinical Pharmacology (12.3) ] , which may reduce the efficacy of these substrates. The magnitude of this decrease may be more pronounced in patients who are dual UGT2B17 and CYP2C19 poor metabolizers [see Clinical Pharmacology (12.3) ]. Hormonal Contraceptives Coadministration of WELIREG with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding [see Clinical Pharmacology (12.3) , Use in Specific Populations (8.3) ] .
Every belzutifan product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Welireg.
What belzutifan pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| 177 | 40 mg | blue | oval | — |
Can you crush or split belzutifan?
At least one belzutifanproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.
What each belzutifan label says about crushing, splitting and chewingWhat people report to the FDA about belzutifan
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 599 reports naming belzutifan, and the FDA flagged 92% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- anaemia88 reports
- hypoxia63 reports
- diarrhoea30 reports
- malignant neoplasm progression29 reports
- dyspnoea22 reports
- fatigue22 reports
- cardiac failure21 reports
- platelet count decreased17 reports
Read these as a signal, not a rate. A report does not mean belzutifan caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is belzutifan?
Belzutifan is an inhibitor of hypoxia-inducible factor-2α (HIF-2α).
Can you take belzutifan with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run belzutifan against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does belzutifan come in?
Across the brands we track, belzutifan is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic belzutifan?
We do not currently list a generic-labelled belzutifan product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Belzutifan: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/belzutifan
- MLA
- “Belzutifan: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/belzutifan.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for belzutifan on DailyMed (NIH) ↗ — including its boxed warning in full.