From the FDA Drug Label
KOSELUGO may cause serious side effects, including: • Heart problems. • Eye problems. • Severe diarrhea. • Skin rash. • Muscle problems (rhabdomyolysis) The most common side effects of KOSELUGO are: • vomiting • stomach‑area pain • nausea • dry skin • muscle and bone pain • feeling of tiredness or lacking energy • fever • sores in your mouth • headache • redness around the fingernails • itching
The side effects of Koselugo medicine include heart problems, eye problems, severe diarrhea, skin rash, and muscle problems. The most common side effects are:
- vomiting
- stomach-area pain
- nausea
- dry skin
- muscle and bone pain
- feeling of tiredness or lacking energy
- fever
- sores in your mouth
- headache
- redness around the fingernails
- itching 1
From the Research
Koselugo (selumetinib) can cause several side effects, including diarrhea, vomiting, nausea, dry skin, muscle pain, fatigue, fever, acne, and rash, with most adverse events being CTCAE grade 1 or 2 and manageable without drug discontinuation, as reported in the most recent study 2.
Common Side Effects
- Diarrhea
- Vomiting
- Nausea
- Dry skin
- Muscle pain
- Fatigue
- Fever
- Acne
- Rash
Serious Side Effects
- Heart problems (such as decreased ejection fraction or heart failure)
- Eye problems (including blurred vision and cataracts)
- Severe skin rashes
- Bleeding problems
- Lung inflammation
Laboratory Abnormalities
- Decreased blood counts
- Elevated liver enzymes
- Increased creatinine phosphokinase levels
Special Considerations
- Children taking this medication may experience impaired growth
- Regular monitoring through blood tests, heart function assessments, and eye exams is typically required while taking this medication
- Patients should report any concerning symptoms to their healthcare provider immediately, especially shortness of breath, swelling, vision changes, or severe skin reactions The side effects of Koselugo are generally manageable, and the medication has been shown to be effective in reducing plexiform neurofibroma volume and improving quality of life in patients with neurofibromatosis type 1, as demonstrated in the study published in 2024 2.