This medication is used to treat anemia caused by certain blood and bone marrow disorders (such as beta thalassemia, myelodysplastic syndromes). In these conditions, your body does not make enough healthy red blood cells. This medication is thought to work by increasing your body's production of healthy red blood cells and hemoglobin. This effect may lessen your symptoms caused by anemia and decrease your need for regular blood transfusions.

Read the Patient Information Leaflet if available from your pharmacist before you start using luspatercept and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

This medication is given by injection under the skin by a health care professional as directed by your doctor, usually once every 3 weeks. The injection is given in the upper arm, thigh, or abdomen. The dosage is based on your medical condition, weight, and response to treatment.

Use this medication regularly to get the most benefit from it. To help you remember, mark your calendar with a reminder.

Tell your doctor if your symptoms do not get better or if they get worse.

Tiredness, headache, muscle/joint pain, dizziness, nausea, or diarrhea may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high. Your doctor may control your blood pressure with medication.

This medication may rarely cause serious (sometimes fatal) problems from blood clots (such as heart attack, stroke, blood clots in the lungs or legs). You may be at increased risk for blood clots if you have had your spleen removed, or have a history of blood clots, or if you are immobile (such as on very long plane flights or being bedridden). If you use estrogen-containing products, these may also increase your risk. Before using this medication, if you have any of these conditions report them to your doctor or pharmacist. Get medical help right away if any of these side effects occur:

• shortness of breath/rapid breathing
• chest/jaw/left arm pain
• unusual sweating
• confusion
• sudden dizziness/fainting
• pain/swelling/warmth in the groin/calf
• sudden/severe headaches
• trouble speaking
• weakness on one side of the body
• sudden vision changes

Some people who have beta thalassemia and are treated with this medication have rarely had a certain tissue problem (extramedullary hematopoietic masses-EMH masses) develop. Your risk for this problem may be higher if you have a past history of EMH masses, or have had your spleen removed, or have an enlarged spleen or liver, or have low hemoglobin levels. Careful monitoring by your doctor may decrease your risk. Tell your doctor right away if you develop symptoms such as:

• severe back pain
• numbness/weakness/loss of ability to control movement in your feet, legs, hand, or arms
• loss of bowel or bladder control

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

See also Side Effects section.

Before using luspatercept, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• high blood pressure
• blood clots
• liver problems
• spleen problems
• a certain tissue problem (extramedullary hematopoietic masses-EMH masses)

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using luspatercept. Luspatercept may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Ask about reliable forms of birth control while using this medication and for at least 3 months after the last dose. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this medication and for 3 months after the last dose. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Lab and/or medical tests (such as hemoglobin levels, complete blood count, blood pressure) must be done while you are using this medication. Keep all medical and lab appointments.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule.

Not applicable. This medication is given in a hospital or clinic or doctor's office and will not be stored at home.