Sotatercept-csrk: what it treats, how it is given, side effects
Last updated September 7, 2026.
**Sotatercept-csrk (brand name Winrevair) is a prescription injection called an activin signaling inhibitor, used for pulmonary arterial hypertension.** It binds proteins in the activin family so the growth signals that drive thickening of the small lung artery walls are rebalanced, which lowers pressure in those vessels over time. It is added to your other pulmonary arterial hypertension medicines rather than replacing them. The most important safety point is that it raises red blood cells and lowers platelets, so hemoglobin and platelet counts must be checked before doses and treatment is held or adjusted based on those numbers.
What does it treat?
Sotatercept-csrk treats pulmonary arterial hypertension, known as PAH or WHO Group 1 pulmonary hypertension, in adults. This is high pressure in the arteries that carry blood from the heart to the lungs, and it shows up as breathlessness with ordinary activity such as stairs or carrying groceries, fatigue, chest pressure, lightheadedness or fainting with exertion, and swelling in the ankles. In studies it increased how far people could walk in six minutes, improved WHO functional class, and reduced the risk of death or clinical worsening events such as hospitalization for PAH or the need to add another PAH drug. It is used together with background therapy, so most people stay on their existing treatment such as a phosphodiesterase-5 inhibitor like tadalafil or sildenafil, an endothelin receptor antagonist like ambrisentan, bosentan, or macitentan, a combination tablet such as macitentan plus tadalafil, or a prostacyclin agent like treprostinil or selexipag. It is not used for pulmonary hypertension caused by left heart disease, lung disease, or chronic blood clots.
How do you take it?
Sotatercept-csrk comes as a lyophilized powder in single-dose vials of 45 mg and 60 mg that is mixed with sterile water and injected under the skin of the abdomen, thigh, or upper arm. Dosing is by weight: the starting dose is 0.3 mg/kg, and the target dose is 0.7 mg/kg given once every 3 weeks. Your clinician checks hemoglobin and platelet count before starting, before each of the first 5 doses, and periodically after that, and treatment is not started if the platelet count is below 50,000 per cubic millimeter. Based on those results the dose may be reduced, held, or restarted at a lower dose, so do not change the amount yourself. There are no food rules because it is an injection, not a tablet, and there is no daily ceiling since doses are at least 3 weeks apart. If you miss a dose, call your care team to get it as soon as possible and to set a new schedule that keeps at least 3 weeks between doses. Call before your next dose if you have new or worsening bruising, nosebleeds, bleeding gums, blood in stool or urine, unusual headaches, or if you become pregnant or plan to.
Side effects to know
- Common: Common effects include headache, nosebleeds, bleeding gums, small red spider-like marks on the skin called telangiectasias, dizziness, rash, diarrhea, flushing, injection site reactions, and rising hemoglobin or falling platelets on blood tests.
- Serious: Get medical help right away and hold further doses until you speak with your clinician if you have serious bleeding such as coughing up blood, vomiting blood, black or tarry stools, a nosebleed that will not stop after 15 to 20 minutes of firm pressure, or heavy vaginal bleeding. Also seek urgent care for a very low platelet count with widespread bruising or pinpoint red spots, or for severe headache, blurred vision, chest pain, or one-sided weakness or slurred speech that can come with too many red blood cells.
Who should not take it?
Do not start sotatercept-csrk if your platelet count is below 50,000 per cubic millimeter, and talk with your clinician first if you have any bleeding disorder, a history of gastrointestinal bleeding or ulcers, liver disease with varices, or recent surgery. Tell your clinician about blood thinners such as warfarin, apixaban, rivaroxaban, or heparin, about antiplatelet drugs such as aspirin or clopidogrel, and about prostacyclin therapies like treprostinil or epoprostenol, since all of these raise bleeding risk when platelets fall. This drug can harm an unborn baby based on how it works and on animal data, so a pregnancy test is needed before the first dose, effective contraception is required during treatment and for at least 4 months after the last dose, and treatment is not used during pregnancy. Do not breastfeed during treatment or for 4 months after the final dose. It may also reduce fertility in females and males, so ask about family planning before you start. The label does not list an alcohol interaction, but heavy or binge drinking lowers platelets and irritates the stomach lining, which adds to bleeding risk, so keep intake light or none while on treatment.
When is it an emergency?
Call 911 in the US for sudden trouble breathing, collapse or fainting, chest pain, coughing up blood, vomiting blood or material that looks like coffee grounds, sudden weakness on one side, slurred speech, or sudden vision loss. Call 911 also for signs of a severe allergic reaction after an injection, including swelling of the lips, tongue, or throat, hives with wheezing, or feeling like you may pass out. For a suspected overdose, an extra dose, or a wrong amount injected, call Poison Control at 1-800-222-1222 right away, since there is no specific antidote and the main concern is a fast rise in red blood cells or a drop in platelets that needs blood tests and possibly phlebotomy or supportive care. Go to an emergency department for a nosebleed that will not stop after 15 to 20 minutes of pinching the soft part of the nose, black or tarry stools, or bruising that spreads without injury.
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Common questions
What is the maximum dose of sotatercept-csrk?
The target and highest labeled dose is 0.7 mg/kg given under the skin once every 3 weeks. Treatment starts at 0.3 mg/kg for the first dose, then moves up to the target dose if your blood counts allow. There is no daily maximum because doses are spaced at least 3 weeks apart. Your clinician may reduce the dose or skip a dose if hemoglobin rises too much or platelets fall, and the dose is recalculated if your weight changes significantly. Never give an extra dose to make up for a delay without calling your care team first.
Can I drink alcohol while taking sotatercept-csrk?
The label does not list a direct interaction between alcohol and sotatercept-csrk. The practical concern is bleeding: this drug can lower your platelet count, and alcohol also lowers platelets and irritates the stomach lining, which raises the chance of a gastrointestinal bleed. Heavy drinking is also hard on the right side of the heart in pulmonary arterial hypertension. If you drink, keep it light and stop entirely if your platelet count is low or you are having nosebleeds or bleeding gums. Bring up your usual intake at your next visit so your monitoring plan matches it.
Is sotatercept-csrk safe in pregnancy or while breastfeeding?
No. Based on how it works and on animal data, sotatercept-csrk can cause fetal harm, so it is not used during pregnancy. A pregnancy test is required before the first dose, and effective contraception is needed during treatment and for at least 4 months after the last dose. Do not breastfeed during treatment or for 4 months after the final dose. The drug may also lower fertility in both females and males, so discuss family planning before you start. If you become pregnant while on it, contact your clinician the same day.
Do I need to take it with food, and how is it stored?
Food does not matter because sotatercept-csrk is injected under the skin, not swallowed. Vials of powder are stored in the refrigerator in the original carton to protect them from light, and the powder is mixed with the supplied sterile water right before use. Rotate injection sites among the abdomen, thigh, and upper arm, and avoid skin that is bruised, red, hard, or tender. Some people are trained to inject at home after a clinician teaches the reconstitution and injection steps. Follow the exact mixing and timing instructions in your product materials, since prepared solution has a limited use window.
What are the signs of too much sotatercept-csrk?
The main signs relate to a fast rise in red blood cells, which thickens the blood: severe or unusual headache, dizziness, flushing, blurred vision, chest pain, or one-sided weakness or slurred speech. A drop in platelets can show up as widespread bruising, pinpoint red spots on the skin, or bleeding that will not stop. If you injected the wrong amount or got an extra dose, call Poison Control at 1-800-222-1222 and your care team right away. Call 911 for chest pain, trouble breathing, fainting, or stroke symptoms. There is no antidote, so management is blood testing and supportive care.
What medicines interact with sotatercept-csrk?
The biggest issue is anything that adds to bleeding risk while your platelets may be low: warfarin, apixaban, rivaroxaban, heparin, aspirin, clopidogrel, and regular NSAIDs like ibuprofen or naproxen. Prostacyclin drugs such as treprostinil, epoprostenol, and selexipag also affect platelet function, and many people with pulmonary arterial hypertension take them alongside sotatercept-csrk, so counts are watched more closely. Sotatercept-csrk is meant to be used with background pulmonary arterial hypertension therapy, so drugs like tadalafil, sildenafil, ambrisentan, and macitentan are usually continued. Tell your clinician about every supplement too, including fish oil, ginkgo, and high-dose vitamin E, which can add to bleeding. Do not stop any pulmonary arterial hypertension medicine on your own.