Spinraza for Spinal Muscular Atrophy: What You Need to Know

Written by Jennifer Phillips, PharmD
Medically Reviewed by Andrea Wessell, PharmD, BCPS on January 16, 2025
5 min read

Spinraza, also known as nusinersen, is a medicine used to treat spinal muscular atrophy (SMA) in children and adults.  SMA is a genetic disease that is passed down through families. It leads to muscle weakness. Muscle weakness may affect normal everyday functions like head movement, sitting without help, walking, swallowing, or breathing. SMA is divided into types based on when symptoms appear. It may be called infantile if the symptoms first appear in infants, juvenile if symptoms first appear in children, or adult-onset if symptoms first appear in adults. 

Below you’ll find common questions and answers about Spinraza.

Spinraza is given as an intrathecal injection, meaning it is injected into the fluid around your spinal cord.  It is usually given at a treatment center by health care providers who know how to give these shots. 
The whole visit may take a few hours.

When you start Spinraza, you will receive four doses close together. These are called loading doses. The first three are given 14 days apart, and the fourth dose is given 30 days after the third dose. After the  fourth dose, you will receive doses every four months after that. 

You may need to have blood drawn and/or urine checked for some laboratory tests before you receive your doses, and occasionally after that. Your health care provider will determine when you need to have your blood drawn for laboratory testing. Your health care provider will decide how often you will get treatment and what the dose will be. 

Spinraza was studied in people with infantile-onset and later-onset SMA. 

  • Infantile-onset trial
    • Spinraza was studied in a trial that included 121 infants who had SMA and were 7 months of age or younger at the start of the trial. 
  • Later-onset trial: 
    • Spinraza was studied in a trial of 126 children who first showed symptoms of SMA after 6 months of age.

In both studies, about two-thirds of the infants received Spinraza and the other one-third received a sham procedure for comparison purposes. The infants who received the sham procedure were given a little needle prick to the skin over the lumbar spine, but they did not receive any actual medicine. 

Here are some traits of people who took part in these studies.

  • Infantile-onset study
    • About half of the people (55%) in this trial were female. 
    • 87% of infants were Caucasian, 2% were Black, and 4% were Asian.
    • The average age at the time of the first dose of Spinraza (or sham injection) was about 6 months.
    • The age when symptoms first started ranged from 2 to 20 weeks, with an average of 8 to 10 weeks.
    • At the start of the trial, all people had decreased muscle tone. Also, most infants had delays in muscle function, most had breathing problems, most had arm or leg weakness, and some had swallowing or feeding problems. 
  • Later-onset trial
    • About half of the people (53%) in this trial were female.
    • 75% of children were Caucasian, 2% were Black, and 18% were Asian.
    • The age at the start of the trial was about 3 to 4 years.
    • The age at the time of first symptoms was 10 to 11 months.
    • The age at the time of SMA diagnosis was about 18 months.
    • At the start of the trial, all people were able to sit with support, but only about 24% to 33% were able to walk with support. None were able to walk independently. 

Infantile-onset trial:  Infants who received Spinraza were more likely to have improvement in their movement milestones, compared to those who received the sham injection. About half of the infants who received Spinraza had an improvement in movement milestones, and no one who received the sham injection had any improvement. 

Late-onset trial: Children who received Spinraza were more likely to have improvements in muscle movement at the end of the 15-month trial. More than half (57%) of children who received Spinraza had improvements, versus 26% of the infants who received the sham injection

Your results may differ from what was seen in clinical trials.

The side effects seen with Spinraza vary based on the time that you start to have symptoms. 

To help prevent headaches, be sure to get enough sleep at night, eat regular meals, drink plenty of water, and limit stress. 

To help prevent constipation, eat lots of fruits and vegetables, increase fiber intake, and drink plenty of water.

To help prevent infections, be sure to wash your hands regularly. Do not touch your face with your hands. Do not drink out of cups or glasses that someone else has used. Contact your health care provider if symptoms do not improve in one to two weeks or if they are severe.

Spinraza may decrease your platelet levels, which may increase your risk of bleeding. You may have to have your blood drawn before your dose to check for signs of bleeding. Tell your health care provider right away if you have any symptoms of low platelet levels such as easy bruising or bleeding, nosebleeds, or bleeding that does not stop. 

Spinraza may cause serious bleeding. Call your health care provider right away if you have any of the following signs of severe bleeding while taking Spinraza.

  • Pink, red, or brown urine (pee)
  • Vomit with blood that looks like coffee grounds
  • Red or black stools (that look like tar)
  • Coughing up blood or blood clots

Spinraza can cause kidney damage. It is important to keep all of your appointments to have your urine checked while taking Spinraza. Tell your health care provider right away if you have any of the following symptoms of kidney damage:

  • Blood in the urine
  • High blood pressure
  • Swelling of the ankles and face
  •  Nausea and vomiting
  • Fever
  • Bubbly urine 
  • Frequent urination at night

These are not all of the possible side effects of Spinraza. Talk with your health care provider if you are having symptoms that bother you. If you experience anything that you think may be caused by Spinraza, you can also report side effects to the FDA at 800-FDA-1088 (800-332-1088).

You will receive your dose of Spinraza at a treatment center. A health care provider will give you your dose of Spinraza. Spinraza must be given by a qualified health care provider who knows how to give medicines intrathecally. 

There may be cost assistance to help you afford Spinraza. You may have options even if you do not have health insurance. The Biogen Copay Program can help you with financial assistance, if you’re eligible. Your health care provider will help you get started. After your doctor prescribes Spinraza, a lead case manager will help you with your insurance benefits. You can speak to a lead case manager by calling 844-4SPINRAZA (844-477-4672).