Side Effects of Iron Infusion
Iron infusions commonly cause adverse reactions in 2-5% of patients, with most side effects being mild and self-limiting, though severe reactions can occur in a minority of patients. 1
Common Side Effects
Immediate Infusion Reactions
Hypersensitivity reactions: Can range from mild to severe, including:
Hypertension: Reported in 4% of patients, often with transient elevations in systolic blood pressure, sometimes accompanied by facial flushing, dizziness, or nausea 2
Injection site reactions: Occur in approximately 3% of patients 2
- Pain, irritation, bruising
- Discoloration
- Erythema
- Swelling
Other Common Side Effects
- Nausea: Most common side effect (7.2% of patients) 2
- Dizziness: Occurs in 2.1% of patients 2
- Vomiting: Occurs in 2% of patients 2
- Headache: Occurs in 1.3% of patients 2
- Dysgeusia (altered taste): Occurs in 1.2% of patients 2
- Rash: Occurs in 1% of patients 2
Serious Side Effects
Hypophosphatemia
- Occurs in 2.1% of patients receiving ferric carboxymaltose 2
- Transient decreases in blood phosphorus levels (<2 mg/dL) observed in 27% of patients in clinical trials 2
- Can be symptomatic and prolonged in some cases 3
- Risk factors include:
- History of gastrointestinal disorders with malabsorption
- Inflammatory bowel disease
- Medications affecting renal tubular function
- Hyperparathyroidism
- Vitamin D deficiency
- Malnutrition 2
Severe Hypersensitivity Reactions
- Anaphylactic/anaphylactoid reactions can occur but are rare
- Mechanisms include:
- Type I (IgE-mediated) anaphylactic reactions caused by preformed dextran antibodies
- Type I anaphylactoid reactions from transient overload of transferrin binding capacity
- Immune complex activation by specific IgG antibodies 1
Differences Between Iron Formulations
Different iron formulations have varying side effect profiles:
Iron dextran: Higher risk of allergic reactions, especially high molecular weight dextran 1
- Can cause dose-related arthralgias and myalgias 4
Newer formulations (iron sucrose, iron gluconate, iron carboxymaltose):
Adverse event rates per 1000 infusions in IBD patients:
- Ferumoxytol: 2.54
- Ferric gluconate: 1.85
- Iron sucrose: 1.74
- Iron dextran: 0.96 5
Risk Factors for Adverse Reactions
- Patients with collagen diseases have increased incidence of adverse effects 1
- Pre-existing vitamin D deficiency, low calcium levels, low phosphate levels, or raised parathyroid hormone levels may increase risk of hypophosphatemia 3
- Larger iron doses are associated with higher risk of severe reactions 1
Management of Reactions
For Mild Reactions
- Stop infusion and restart 15 minutes later at a slower rate 1
- Cold compresses and elevation of affected limb for local reactions 4
For Moderate to Severe Reactions
- Stop infusion immediately
- Notify physician
- Monitor vital signs
- Administer IV corticosteroids for moderate reactions
- For severe reactions/anaphylaxis:
- Administer epinephrine 0.3 mg IM
- Consider β2 agonist nebulizer (albuterol)
- Call emergency services 1
Prevention of Adverse Reactions
- Correct pre-existing hypophosphatemia before initiating therapy 2
- Monitor serum phosphate levels in at-risk patients 2
- Consider slower infusion rates to reduce reaction risk 1
- For patients with previous allergic reactions, pre-treatment with methylprednisolone, diphenhydramine, and ephedrine may allow safe administration 1
Iron infusions are generally safe with serious adverse events being rare, but clinicians should be vigilant about monitoring for and managing potential side effects, particularly in high-risk patients.