Can I take iron during an infection? Risks and Considerations

December 4, 2025 •

3 min read

The body initiates a sophisticated defense mechanism known as 'nutritional immunity' during an infection, actively sequestering iron away from invading pathogens. This process makes the crucial decision of whether to continue or pause iron supplementation during illness complex and highly debated.

Quick Summary

The body purposefully restricts iron to inhibit bacterial growth during infection. Supplemental iron can undermine this defense, so pausing supplementation is often a safer approach during acute illness.

Key Points

Pause Supplements During Active Illness: During an infection, the body limits iron access to pathogens, so supplementing can be counterproductive and should be paused, especially with bacterial infections and fever.
IV Iron is High-Risk: Intravenous iron is strongly contraindicated during active infection due to a significant spike in circulating free iron that can fuel pathogen growth.
Understand Nutritional Immunity: The body's natural defense system involves sequestering iron from pathogens via the hormone hepcidin, a process that supplementation can disrupt.
Distinguish Anemia Types: It is crucial to determine whether you have true iron deficiency or anemia of inflammation, as the latter can arise during sickness and should not be treated with iron.
Consult a Doctor: The decision to take or pause iron during an infection is complex and should always be made in consultation with a healthcare professional based on individual circumstances.

The Complex Relationship Between Iron and Infection

Iron is essential for immune function, but also crucial for pathogen growth. During an infection, the body limits available iron to starve invading microbes, a process called nutritional immunity.

The Body's Natural Defense: Nutritional Immunity

During infection, the immune system reduces circulating iron through the hormone hepcidin, which blocks iron release and absorption. This nutritional immunity hinders pathogen replication while the body tries to balance this with iron needed for its own immune cells.

Why Excess Iron Can Be Dangerous During Sickness

Supplementing with iron during an infection can counteract the body's defense. Excess iron, especially non-transferrin-bound iron from high doses, can be used by pathogens. Studies suggest this may worsen infections and increase hospital stays.

Oral vs. Intravenous Iron: Which Poses a Greater Risk?

The risk of iron supplementation during infection varies by administration method.


Feature	Oral Iron Supplementation	Intravenous (IV) Iron
Risk Profile During Infection	Generally lower risk for most mild infections, with absorption regulated by the gut. May increase diarrhea risk.	Significantly higher risk due to a direct spike in circulating iron, increasing non-transferrin-bound iron. Strongly contraindicated during active infection.
Mechanism of Risk	Unabsorbed iron can alter gut bacteria, potentially promoting pathogen growth.	Increases non-transferrin-bound iron (NTBI), accessible to pathogens for growth. Impairs immune cell function.
Medical Consensus	Withholding during active infection is often a reasonable approach, especially for bacterial infections.	Strongly advised against during active infection by numerous guidelines due to increased risk.
Timing of Use	Often paused during acute illness and resumed once stable, based on assessment.	Only administered once infection has completely resolved, as confirmed by a physician.

Iron Supplements and Sickness: When to Pause

For mild infections, pausing iron may not be critical but is often prudent. For serious or chronic infections, or for those receiving IV iron, supplementation should be paused under medical supervision.

When to Reconsider Iron During Sickness

Acute Bacterial Infections: Pausing iron is highly recommended with bacterial infections, as providing iron can aid bacterial growth.
IV Iron Treatment: Administering intravenous iron during active infection is strongly advised against due to the risk of fueling pathogens.
Fever: Pausing iron during a fever, a sign of active immune response, is a sound practice.

Key Factors Influencing the Decision

A healthcare provider should always be consulted regarding iron supplementation during illness. Factors include: type and severity of infection, severity of iron deficiency, overall health, type of iron (oral vs. IV), and dietary iron absorption.

Iron Deficiency vs. Anemia of Inflammation

Distinguishing between simple iron deficiency anemia and anemia of inflammation is crucial during sickness. Iron deficiency is a lack of stores, while anemia of inflammation is the body's inflammatory response sequestering iron despite sufficient stores. Treating anemia of inflammation with iron can be ineffective and potentially harmful by aiding pathogens. A healthcare provider can use blood tests to differentiate and recommend treatment.

Conclusion: The Final Verdict on Iron and Infection

Taking iron supplements during active infection carries risks, especially with bacterial infections and IV administration. The body's nutritional immunity aims to limit iron for pathogens, and supplementation can counteract this. Temporarily pausing iron during active infection, particularly bacterial or with fever, is generally prudent. Always consult a medical professional for personalized advice, considering individual health, infection severity, and supplementation type. Decisions should balance supporting the immune system and avoiding feeding pathogens. Iron Homeostasis and the Inflammatory Response

Frequently Asked Questions

Yes, taking supplemental iron during an active bacterial infection can potentially make it worse. Pathogens like bacteria need iron to grow, and adding extra iron to your system can inadvertently fuel their proliferation.

During an infection, the body enters a state of 'nutritional immunity,' where it intentionally lowers the amount of free iron available in the bloodstream. This is a defensive strategy to starve invading pathogens of a crucial nutrient they need to replicate.

For a mild, temporary illness like a cold, the risk is generally low, but pausing supplementation is often a cautious approach. For more severe or bacterial infections, or if you have a fever, it is safer to pause and consult your doctor.

Yes. The risks associated with intravenous (IV) iron during an active infection are significantly higher and are strongly advised against by medical guidelines. Oral iron poses a lower risk, but pausing it is still recommended during active illness.

Anemia of inflammation is a condition that occurs during chronic or inflammatory diseases, where the body's immune response sequesters iron. This can result in low iron levels in the blood, but it is a regulatory defense mechanism and should not be treated with iron supplements during the acute phase.

Iron from food is absorbed more slowly and is regulated differently by the body than concentrated supplemental iron, posing a much lower risk. The primary concern is with the unnatural bolus of iron delivered via supplements, especially intravenous ones.

You should only resume iron supplementation once the infection has fully resolved. A doctor can help determine the appropriate timing and monitor your iron levels to ensure a safe transition.