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Amondys 45 Side Effects

Generic name: casimersen

Medically reviewed by Last updated on Sep 14, 2022.

Note: This document contains side effect information about casimersen. Some dosage forms listed on this page may not apply to the brand name Amondys 45.

Applies to casimersen: intravenous solution.

Serious side effects of Amondys 45

Along with its needed effects, casimersen (the active ingredient contained in Amondys 45) 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 casimersen:

More common

  • Body aches or pain
  • chills
  • cough
  • difficulty in moving
  • dizziness
  • ear congestion
  • fast, pounding, or irregular heartbeat
  • fever
  • headache
  • joint pain
  • lightheadedness
  • loss of voice
  • muscle pain or stiffness
  • nausea
  • runny or stuffy nose
  • sneezing
  • sore throat
  • stomach pain
  • swelling of the face, ankles, or hands
  • tender, swollen glands in the neck
  • trouble breathing
  • trouble swallowing
  • unusual tiredness or weakness
  • vomiting

Incidence not known

  • Agitation
  • blood in the urine
  • coma
  • confusion
  • decreased urine output
  • depression
  • irritability
  • lethargy
  • muscle twitching
  • rapid weight gain
  • seizures
  • stupor

Other side effects of Amondys 45

Some side effects of casimersen 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

  • Bleeding, blistering, burning, coldness, discoloration of skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  • change in hearing
  • earache or pain in the ear
  • ear drainage

For Healthcare Professionals

Applies to casimersen: intravenous solution.


The most commonly reported adverse reactions have included respiratory tract infection, cough, pyrexia, headache, arthralgia, and oropharyngeal pain.[Ref]

Nervous system

Very common (10% or more): Headache (32%)


Very common (10% or more): Pyrexia (33%)

Frequency not reported: Ear pain, ear infection, posttraumatic pain


Very common (10% or more): Arthralgia (21%)


Very common (10% or more): Oropharyngeal pain (21%)

Frequency not reported: Nausea


Very common (10% or more): Respiratory tract infections (65%), cough (33%)

Respiratory tract infections include pharyngitis, nasopharyngitis, and rhinitis. In clinical trials, respiratory tract infections were reported in 65% of patients receiving the drug compared to 55% in the placebo group. Cough was reported in 33% of patients receiving this drug compared to 26% in placebo.

Frequently asked questions


1. "Product Information. Amondys 45 (casimersen)." Sarepta Therapeutics (2021):

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.