What are the side effects of Orserdu (elacestrant)?

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Last updated: October 5, 2026 • View editorial policy

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Orserdu (Elacestrant) Side Effects

The most common side effects of Orserdu include musculoskeletal pain (41%), nausea (35%), increased cholesterol (30%), elevated liver enzymes (AST 29%, ALT 17%), increased triglycerides (27%), fatigue (26%), decreased hemoglobin (26%), vomiting (19%), and gastrointestinal symptoms including diarrhea (13%), constipation (12%), and abdominal pain (11%). 1

Most Frequent Adverse Reactions (≥10%)

Based on the pivotal EMERALD trial data in the FDA label, the following side effects occurred in patients taking Orserdu 1:

Musculoskeletal and Gastrointestinal Effects

  • Musculoskeletal pain: 41% (Grade 3: 7%)
  • Nausea: 35% (Grade 3: 2.5%) - occurred early, with 70-80% within first 2 weeks, mostly mild, and 60-65% resolved within first month
  • Vomiting: 19% (Grade 3: 0.8%)
  • Diarrhea: 13% (Grade 3: 1%)
  • Constipation: 12% (Grade 3: 0%)
  • Abdominal pain: 11% (Grade 3: 1%)
  • Dyspepsia: 10% (Grade 3: 0%)

Laboratory Abnormalities

  • Increased cholesterol: 30% (Grade 3-4: 1%)
  • Increased AST: 29% (Grade 3-4: 3%)
  • Increased triglycerides: 27% (Grade 3-4: 2%)
  • Increased ALT: 17% (Grade 3-4: 2%)
  • Decreased hemoglobin: 26% (Grade 3-4: 2%)
  • Decreased sodium: 16% (Grade 3-4: 1%)
  • Increased creatinine: 16% (Grade 3-4: 0%)

Other Common Effects

  • Fatigue: 26% (Grade 3: 2%)
  • Decreased appetite: 15% (Grade 3: 0.8%)
  • Headache: 12% (Grade 3: 1%)
  • Hot flush: 11% (Grade 3: 0%)

Serious Adverse Reactions

Serious adverse reactions occurred in 12% of patients, with musculoskeletal pain (1.7%) and nausea (1.3%) being most common. Fatal adverse reactions occurred in 1.7% of patients (cardiac arrest, septic shock, diverticulitis, and unknown cause). 1

Treatment Modifications

  • Permanent discontinuation: 6% of patients (most commonly due to musculoskeletal pain 1.7% and nausea 1.3%)
  • Dose interruptions: 15% of patients (most commonly nausea 3.4%, musculoskeletal pain 1.7%, increased ALT 1.3%)
  • Dose reductions: 3% of patients (most commonly nausea 1.7%)

Lipid Abnormalities - Key Warning

Hypercholesterolemia and hypertriglyceridemia are serious side effects requiring monitoring. Your healthcare provider must check lipid levels before starting treatment and regularly during therapy. 1

Newly Identified Real-World Adverse Events

Recent post-marketing surveillance has identified additional potential adverse events not prominently featured in the original label 2, 3:

  • Pathological fractures
  • Gastroesophageal reflux disease
  • Hypokalemia
  • Lymphedema
  • Dehydration
  • Disease progression (most commonly reported in real-world data)
  • Drug ineffectiveness
  • Bone pain

The median onset time for adverse events is 44 days, with most occurring within the first month of treatment. 2

Clinical Context

The overall safety profile is manageable, with most adverse events being Grade 1-2 in severity. Taking Orserdu with food may help reduce nausea and vomiting. 1 Real-world studies confirm the tolerability profile observed in clinical trials, with dose reductions necessary in approximately 15% of cases and permanent discontinuation due to toxicity in only 4% of patients. 4

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.