Iron Drug Interactions – Clinical Significance

iron drug interactions

Iron drug interactions are very common.  Use of iron products like ferrous sulfate is also extremely common.  Two diseases that iron deficiency can cause is anemia and restless leg syndrome.  There are iron drug interactions that can reduce the effectiveness of iron.  More commonly, iron can impact other medications.  Here’s a few common iron drug interactions that you should be aware of.

  • Iron Binding Interactions.  There are numerous examples here.
    • Antibiotics may be the most concerning.  Oral drugs like fluoroquinolones (levofloxacin and ciprofloxacin) can potentially be less effective when they are given at or near the same time as iron.  You could imagine this being a major issue in a patient who is battling pneumonia or a urinary tract infection. Cefdinir and tetracyclines are two other examples of antibiotics that may be reduced by iron binding.  Here’s a case scenario of antibiotic failure due to one of these interactions.
    • Levothyroxine.  This medication can also be bound up by iron and concentrations can be reduced.  As long as TSH levels are within normal limits and the patient is asymptomatic, we are usually good.  Keep an eye out for new starts or dose increases.  Variable TSH can be an indicator of potential interactions as well.
    • Levodopa.  Iron can reduce concentrations of levodopa.  This is a very sensitive medication used in the management of Parkinson’s.  Starting an iron supplement could put a patient in a subtherapeutic state leading to more symptoms of Parkinson’s disease.
  • Reducing iron’s effectiveness.  Iron is best absorbed in an acidic environment.  Drugs that suppress the stomach’s acid pumps or reduces the amount of acid in the stomach may impair absorption of the iron.  H2 blockers, PPI’s, Tums, Rolaids, and other similar products can all reduce or suppress acid production. If hemoglobin or iron stores are not responding, we may try to get around this by administering vitamin C with the iron to increase the acidic environment of the stomach.

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  1. Jim Ramsey

    What’s the answer for minimizing the impact of binding interactions?

    • Eric Christianson

      Good question! Depends upon the situation. One important thing to assess is if iron is necessary long term. If not, discontinue it and don’t worry about the interaction. In short courses of antibiotics, we may be able to hold the iron if the anemia is not a dire situation. Otherwise, our option is to try to maximize the time between the taking iron and the interacting medication. If it is something we can monitor a lab for like levothyroxine, consistency is probably the best route. – hope that helps! Eric

  2. Murrays Pharmacy

    Thank you very much, this post is really informative.



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Written By Eric Christianson

August 12, 2018

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