Skip to main content

Nusinersen Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Jun 9, 2022.

For the Consumer

Applies to nusinersen: intrathecal solution

Side effects requiring immediate medical attention

Along with its needed effects, nusinersen may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking nusinersen:

More common

  • Agitation
  • black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • body aches or pain
  • chills
  • coma
  • confusion
  • cough
  • decreased urine output
  • depression
  • difficulty with breathing
  • dizziness
  • ear congestion
  • fever
  • headache
  • irritability
  • lethargy
  • loss of voice
  • muscle twitching
  • nausea
  • pinpoint red spots on the skin
  • rapid weight gain
  • runny or stuffy nose
  • seizures
  • sneezing
  • sore throat
  • stupor
  • swelling of the face, ankles, or hands
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Side effects not requiring immediate medical attention

Some side effects of nusinersen may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Back pain
  • difficulty having a bowel movement (stool)
  • teething

Less common

  • Change in hearing
  • ear drainage
  • earache or pain in the ear

For Healthcare Professionals

Applies to nusinersen: intrathecal solution


The most commonly occurring adverse reactions have included lower respiratory infection and constipation in patients with infantile-onset SMA; pyrexia, headache, vomiting, and back pain in patients with later onset SMA.


Lower respiratory tract infection was the most common adverse reaction occurring in 55% of drug treated patients compared to 37% of those receiving sham. At baseline, patients receiving drug had a higher percentage of paradoxical breathing (89% vs 66%), pneumonia or respiratory symptoms (35% vs 22%) swallowing or feeding difficulties (51% vs 29%), and need for respiratory support (26% vs 15%). Lower respiratory infection includes adenovirus infection, bronchiolitis, bronchitis, viral bronchitis, corona virus infection, Influenza, lower respiratory tract infection, lower respiratory tract infection viral, lung infection, parainfluenzae virus infection, pneumonia, pneumonia bacterial, pneumonia influenza, pneumonia Moraxella, pneumonia parainfluenzae viral, pneumonia pneumococcal, pneumonia pseudomonal, pneumonia respiratory syncytial viral, pneumonia viral, and respiratory syncytial virus bronchiolitis[Ref]

Very common (10% or more): Lower respiratory infection (55%)

Common (1% to 10%): Upper respiratory congestion, epistaxis, respiratory tract congestion[Ref]


In sham-controlled studies, 58% (71/123) of patients with infantile-onset and later-onset SMA receiving drug had elevated urine protein compared with 34% (22/65) of those receiving sham.[Ref]

Very common (10% or more): Elevated urinary protein (58%)[Ref]

Nervous system

Communicating hydrocephalus not related to meninigitis or bleeding has been reported; some patients have been managed with implantation of ventriculo-peritoneal shunt (VPS). Five cases have been reported to manufacturer as of July 2018.[Ref]

Very common (10% or more): Headache (29%)

Frequency not reported: Post-lumbar puncture syndrome

Postmarketing reports: Meningitis, hydrocephalus, communicating hydrocephalus[Ref]


Very common (10% or more): Back pain (25%)

Frequency not reported: Growth reduction[Ref]

In a controlled study in infants, a reduction in growth of infants was observed; it is unknown if this would be reversible with cessation of treatment.[Ref]


In sham-controlled studies in patients with infantile-onset and later-onset SMA, 16% (24/146) of patients receiving drug developed a platelet level below the lower limit of normal, compared to 14% (10/72) of those receiving sham. Platelet levels at baseline were high, normal, or unknown. Among patients with later-onset SMA, 2 drug treated patients developed platelet counts less than 50,000 cells/microliter; the lowest level was 10,000 cells/microliter recorded on study day 28.[Ref]

Very common (10% or more): Platelet levels below the lower limit of normal (16%)[Ref]


Very common (10% or more): Pyrexia (43%)

Common (1% to 10%): Ear infection, fall[Ref]


Frequency not reported: Rash[Ref]

Rash has been reported in 2 patients. The first patient developed painless, red macular lesions on the forearm, leg, and foot over an 8-week period after being on the drug for 8 months. Over 4 weeks, the lesions ulcerated and scabbed over, and resolved over several months. In the second patient, red macular skin lesions developed on the cheek and hand after receiving the drug for 10 months. They resolved over 3 months. Both patients continued to receive the drug.[Ref]


Severe hyponatremia requiring salt supplementation for 14 months was reported in an infant with symptomatic SMA.[Ref]

Common (1% to 10%): Decreased weight

Frequency not reported: Hyponatremia[Ref]


Very common (10% or more): Constipation (35%), vomiting (29%)

Common (1% to 10%): Flatulence[Ref]


Common (1% to 10%): Anti-drug antibodies


1. "Product Information. Spinraza (nusinersen)." Biogen Idec Inc (2017):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.