Management of Allergic Reactions to Iron Supplements

Introduction to Iron Reactions

The American Gastroenterological Association and the American Society of Hematology recognize that most reactions to intravenous iron are not true allergies but complement activation-related pseudo-allergy (CARPA), while true allergic reactions to oral iron are extremely rare 1, 2

For patients experiencing mild to moderate reactions, the American Society of Hematology recommends stopping the infusion immediately and switching the IV line to normal saline to keep the vein open 3
The American Society of Hematology suggests monitoring the patient for 15 minutes, as most reactions are self-limiting and resolve spontaneously 3
The American Society of Hematology advises against using diphenhydramine, as it can worsen hypotension, tachycardia, and sedation, potentially converting a minor reaction into a serious adverse event 3
For severe reactions, the American Society of Hematology recommends administering epinephrine 0.3-0.5 mg intramuscularly in the anterolateral thigh immediately 3

The American Society of Hematology suggests that if symptoms completely resolve and iron is still needed, rechallenge can be considered, and the infusion rate should be reduced to 50% of the initial rate 3

The American Gastroenterological Association recommends switching to alternate-day dosing to reduce side effects for patients experiencing gastrointestinal side effects from oral iron 1
The American Gastroenterological Association suggests trying different oral formulations, such as ferrous sulfate, gluconate, fumarate, or bisglycinate, for patients who experience side effects from oral iron 1
The American Society of Hematology recommends using iron sucrose, as it is the safest IV formulation with the lowest risk of allergic reactions 4

The American Society of Hematology notes that CARPA occurs without prior sensitization and is characterized by flushing, myalgias, arthralgias, back pain, and chest pressure, lacking signs of true anaphylaxis 2

Patients with multiple drug allergies, severe atopy or asthma, systemic inflammatory diseases, or fast infusion rates are at higher risk for reactions, according to the American Society of Hematology 4, 5

The American Society of Hematology recommends that all IV iron must be administered by personnel trained in emergency treatment with immediate access to epinephrine and corticosteroids 4
The American Society of Hematology suggests that premedication should be limited to patients with substantial risk factors, such as multiple drug allergies, prior reaction, or asthma 3