What the label lists and what reports show
Sotatercept-csrk side effects
Sotatercept-csrk's FDA label: “The most common (≥10% in patients receiving WINREVAIR and 5% more than placebo) adverse reactions were infections, epistaxis, telangiectasia, diarrhea, headache, rash, increased hemoglobin, dizziness, erythema, and gingival bleeding.” FAERS holds 5,010 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is headache (668 reports).
- No generic listed
Check it at the source: the sotatercept-csrk FDA label on DailyMed (effective August 12, 2026, Merck Sharp & Dohme LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of WINREVAIR?WINREVAIR may cause serious side effects including: High level of hemoglobin in your blood. High levels of hemoglobin are common with WINREVAIR and can be severe and increase your risk for blood clots. Your healthcare provider will do blood tests to check your hemoglobin levels before starting and regularly during treatment with WINREVAIR. Severely low number of platelets in your blood. Low platelet counts are common with WINREVAIR and can be severe and increase your risk of bleeding. Your healthcare provider will do blood tests to check your platelet levels before starting and regularly during treatment with WINREVAIR. Tell your healthcare provider if you develop easy bruising or bleeding, bleeding that does not stop, or nosebleeds. Serious bleeding. […]
Source: FDA drug label, Merck Sharp & Dohme LLC, effective August 12, 2026 (SPL set 21693ee2-cd23-4137-ac67-066bb3a4a9b7), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common (≥10% in patients receiving WINREVAIR and 5% more than placebo) adverse reactions were infections, epistaxis, telangiectasia, diarrhea, headache, rash, increased hemoglobin, dizziness, erythema, and gingival bleeding.
Table 4: Adverse Reactions ≥10% in Patients Receiving WINREVAIR and at least 5% More Than Placebo in ZENITH
| Adverse reaction | WINREVAIR N=86 | Placebo N=86 |
|---|---|---|
| Infections | 58 (67.4) | 38 (44.2) |
| Epistaxis | 39 (45.3) | 8 (9.3) |
| Diarrhea | 22 (25.6) | 15 (17.4) |
| Telangiectasia | 22 (25.6) | 3 (3.5) |
| Increased hemoglobin | 13 (15.1) | 1 (1.2) |
| Rash | 9 (10.5) | 4 (4.7) |
| Erythema | 9 (10.5) | 3 (3.5) |
| Gingival bleeding | 9 (10.5) | 2 (2.3) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in the labeling: Erythrocytosis [see Warnings and Precautions (5.1) ] Severe Thrombocytopenia [see Warnings and Precautions (5.2) ] Serious Bleeding [see Warnings and Precautions (5.3) ] Embryo-Fetal Toxicity [see Warnings and Precautions (5.4) ] Impaired Fertility [see Warnings and Precautions (5.5) ] The most common (≥10% in patients receiving WINREVAIR and 5% more than placebo) adverse reactions were infections, epistaxis, telangiectasia, diarrhea, headache, rash, increased hemoglobin, dizziness, erythema, and gingival bleeding. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Merck Sharp & Dohme LLC at 1-877-888-4231 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. STELLAR The following data reflect exposure to WINREVAIR in the STELLAR trial. Adult PAH patients with WHO FC II or III (n=323) were randomized in a 1:1 ratio to receive WINREVAIR or placebo in combination with background standard of care therapies. …
Source: FDA drug label, Merck Sharp & Dohme LLC, effective August 12, 2026 (SPL set 21693ee2-cd23-4137-ac67-066bb3a4a9b7), via openFDA; the full label on DailyMed
What do FAERS reports show?
5,010 reports list sotatercept-csrk among the medicines taken, each a report of something that happened, not proof the medicine caused it; 208 are coded as a death and 2,060 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 rose sharply in 2025 (2,250, against a median of 0 a year): FAERS counts follow reporting, which news, litigation and label changes can drive, not how often a reaction happens. Of the 22 reactions below, 6 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Sotatercept-csrk: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions