What are the side effects of Injectafer (ferric carboxymaltose)?

Injectafer Side Effects

Injectafer (ferric carboxymaltose) carries a unique and clinically significant risk of hypophosphatemia, particularly with repeated dosing, which can lead to serious complications including fatigue, osteomalacia, and bone fractures. 1, 2

Most Serious Side Effects

Hypophosphatemia (Most Important Unique Risk)

• Hypophosphatemia is the hallmark adverse effect of Injectafer that distinguishes it from other IV iron formulations 1
• Can be prolonged and severe, especially with repeated dosing 1
• May lead to:
  • Fatigue and muscle weakness 2
  • Bone and joint pain 2
  • Osteomalacia (bone softening) 1
  • Pathologic fractures 2
• Use Injectafer with great caution in patients with poor absorption or nutrition, and check phosphate levels before repeat treatment if given within 3 months 1, 2

Life-Threatening Allergic Reactions

• Serious hypersensitivity reactions including anaphylaxis can occur and may be fatal 2
• Symptoms include:
  • Hypotension and loss of consciousness 2
  • Difficulty breathing and wheezing 2
  • Swelling, rash, hives, and itching 2
  • Cold/clammy skin, cyanosis of extremities 2
  • Tachycardia 2
• Patients must be monitored for at least 30 minutes after infusion with resuscitation equipment immediately available 2

Infusion Reactions (Pseudo-Allergic)

• Idiosyncratic infusion reactions can mimic allergic reactions 1
• For mild reactions: stop infusion, restart after 15 minutes at slower rate 1
• For severe reactions: corticosteroids may be beneficial 1
• Avoid diphenhydramine as its side effects can be mistaken for worsening reactions 1

Common Side Effects

In Adults

• Nausea 2, 3
• Hypertension (sometimes with facial flushing) 2, 3
• Flushing 2
• Injection site reactions 2, 3
• Skin redness 2
• Dizziness 2, 3
• Headache 3
• Abdominal pain 3
• Constipation and diarrhea 3

In Children (Age ≥1 Year)

• Hypophosphatemia (most common) 2
• Injection site reactions 2
• Rash 2
• Headache 2
• Vomiting 2

Hypertension Risk

• Elevated blood pressure can occur during or after infusion 2
• May be accompanied by facial flushing, dizziness, or nausea 2
• Blood pressure monitoring is required after administration 2

Laboratory Abnormalities

• Transient, asymptomatic hypophosphatemia is the most common laboratory finding 4, 5
• Transient elevations in serum iron, ferritin, and transferrin saturation occur 3

Comparative Tolerability

• Generally better tolerated than oral ferrous sulfate due to lower incidence of gastrointestinal adverse effects 3, 4
• Rash and injection site reactions are more common with Injectafer than oral iron 3
• Gastrointestinal side effects are more frequent with oral iron 3
• Similar overall adverse event rates to iron sucrose in hemodialysis patients 3

Critical Clinical Pitfall

The hypophosphatemia risk with Injectafer is dose-dependent and cumulative—this formulation should be used only with great care in patients requiring repeated dosing, and phosphate levels must be checked before retreatment if administered within 3 months of the last dose. 1, 2 This distinguishes Injectafer from other IV iron preparations and makes it a poor choice for patients with malabsorption, malnutrition, or those requiring frequent iron repletion. 1