Post-Iron Infusion Reactions

Introduction to Post-Infusion Symptoms

Sweating, fatigue, and palpitations can represent delayed infusion reactions, which are distinct from immediate hypersensitivity reactions and typically occur hours to days after administration, according to the American College of Physicians 1.
Extreme fatigue, along with myalgias, arthralgias, and fever, constitutes a flu-like syndrome that can persist up to 24 hours post-infusion and is managed with NSAIDs, as recommended by the American Academy of Family Physicians 1, 2.

Cardiovascular symptoms including tachycardia and flushing are recognized manifestations of infusion reactions, though severe reactions (anaphylaxis, severe hypotension) are exceedingly rare at <1:250,000 administrations with modern formulations, as stated by the National Institute of Nutrition 3.
Most infusion reactions are due to complement activation-related pseudo-allergy (CARPA) rather than true IgE-mediated anaphylaxis, meaning they are not traditional allergic reactions, according to the American College of Allergy, Asthma, and Immunology 2.

NSAIDs are first-line treatment for post-infusion flu-like symptoms, fatigue, and body aches, as recommended by the American Academy of Family Physicians 1.
For reactions during or immediately after infusion, the infusion should be stopped immediately and IV line switched to normal saline, and vital signs should be monitored for at least 15 minutes, according to the American Heart Association 1, 2.
Avoid first-generation antihistamines (like diphenhydramine) and vasopressors, as these can paradoxically worsen minor reactions into serious adverse events, as warned by the American College of Emergency Physicians 1, 2.

Slower infusion rates reduce the risk of reactions, as recommended by the American Society of Health-System Pharmacists 1, 2.
Different iron formulations have varying side effect profiles—ferric carboxymaltose can be given as 1000 mg over 15 minutes with similar safety to other preparations, according to the European Society for Clinical Nutrition and Metabolism 3, 4.