Iron

Iron/Drug Interactions:

  • Acetohydroxamic acidAcetohydroxamic acid: According to secondary sources, acetohydroxamic acid (AHA, Lithostat?) is prescribed to decrease urinary ammonia and may be synergistic with antibiotics or other kidney stone treatment. Use with iron supplements may reduce the efficacy of both agents.
  • AllopurinolAllopurinol: Allopurinol (Zyloprim?), a medication used to treat gout, may decrease iron storage in the liver (159).
  • Aminosalicylic acidAminosalicylic acid: Aminosalicylic acid (para-aminosalicylic acid; PAS, Paser) may cause a malabsorption syndrome (weight loss, iron and vitamin depletion, steatorrhea) (160). A qualified healthcare provider should be contacted immediately if any of these symptoms are experienced.
  • Angiotensin II-converting enzyme (ACE) inhibitors and angiotensin-converting enzyme receptor blockersAngiotensin II-converting enzyme (ACE) inhibitors and angiotensin-converting enzyme receptor blockers: Oral supplementation of ferrous sulfate appears to subside cough associated with angiotensin-converting enzyme (ACE) inhibitors, such as captopril (Capoten?), enalapril (Vasotec?), and lisinopril (Prinivil?, Zestril?) (161).
  • AntacidsAntacids: Concurrent administration with antacids may reduce iron absorption (162). Clinically significant effects are unlikely with adequate dietary iron intake.
  • AntibioticsAntibiotics: Iron has been found to decrease the absorption of fluoroquinolone (163) and tetracycline antibiotics (164). Fluoroquinolones include ciprofloxacin (Cipro?), levofloxacin (Levaquin?), ofloxacin (Floxin?), and others. Some of the tetracycline antibiotics include doxycycline (Vibramycin?), minocycline (Minocin?), and tetracycline (Achromycin?).
  • AspirinAspirin: Regular use of aspirin may contribute to iron deficiency in the elderly (165).
  • BisphosphonatesBisphosphonates: Preliminary research has shown that concurrent iron administration inhibits the absorption of clodronate, a bisphosphonate drug (166).
  • ChloramphenicolChloramphenicol: Secondary sources suggest that chloramphenicol (Chloromycetin?) may reduce the efficacy of iron therapy in iron deficiency anemia.
  • CholestyramineCholestyramine: Cholestyramine (Questran?) may bind iron in the gut, reducing its absorption (167).
  • DimercaprolDimercaprol: According to prescribing information for dimercaprol, iron salts and dimercaprol may form a nephrotoxic complex when used together.
  • H2 blockersH2 blockers: H2 blockers such as cimetidine (Tagamet?), ranitidine (Zantac?), famotidine (Pepcid?), or nizatidine (Axid?) may reduce iron absorption. According to expert opinion, iron supplements are not usually required unless high doses of H2 blockers are being used (168).
  • Human recombinant erythropoietin (EPO)Human recombinant erythropoietin (EPO): Bone marrow iron deposits have been shown to decrease significantly in patients on human recombinant erythropoietin therapy (169).
  • Iron chelatorsIron chelators: Desferrioxamine and deferiprone are both iron-chelating drugs that lower iron levels (104; 105; 106).
  • LevodopaLevodopa: There is some evidence that iron forms chelates with levodopa (Sinemet?) and reduces levodopa bioavailability (170).
  • LevothyroxineLevothyroxine: Evidence suggests that iron may decrease the absorption and efficacy of levothyroxine (Levoxyl?, Synthroid?) (171).
  • MethyldopaMethyldopa: Ferrous sulfate has been shown to decrease the absorption of methyldopa (Aldomet?), resulting in increased blood pressure (172).
  • Mycophenolate mofetilMycophenolate mofetil: Some evidence suggests that oral iron supplements markedly reduce absorption of mycophenolate mofetil (CellCept?) (173). However, other studies suggest that mycophenolate pharmacokinetics is not affected by iron supplementation (174; 175; 176).
  • Nonsteroidal anti-inflammatory agents (NSAIDs)Nonsteroidal anti-inflammatory agents (NSAIDs): NSAIDs, such as ibuprofen (Advil?), naproxen (Aleve?), or ketorolac (Toradol?), may cause mucosal damage and bleeding throughout the gastrointestinal tract. Chronic blood loss associated with long-term use of these agents may contribute to iron deficiency anemia (177). Iron-rich food intake may be advised as an alternative.
  • Pancreatic enzymesPancreatic enzymes: There is some evidence that pancreatic enzyme supplements, such as Cotazym?, Creon?, Pancrease?, Ultrase?, and Viokase?, may reduce iron absorption and contribute to iron deficiency (178).
  • PenicillaminePenicillamine: Oral iron supplements may reduce absorption of penicillamine (Cuprimine?, Depen?), probably due to chelate formation (179).
  • Proton pump inhibitorsProton pump inhibitors: Long-term therapy with proton pump inhibitors, such as omeprazole (Prilosec?), lansoprazole (Prevacid?), or esomeprazole (Nexium?), has been associated with iron deficiency (180).

    • Iron/Herb/Supplement Interactions:

  • AcaciaAcacia: According to secondary sources, acacia forms an insoluble gel with ferric iron. The clinical significance of this is unknown.
  • Ascorbic acidAscorbic acid: Evidence suggests that ascorbic acid increases the bioavailability of dietary iron by enhancing iron absorption (181; 182), and it may (183) or may not (184; 185) improve iron status.
  • Black teaBlack tea: Evidence suggests that black tea has no effects on iron status in people without risk for anemia but could potentially affect iron levels in anemic populations (186).
  • CalciumCalcium: Human studies have shown that calcium (from calcium salts or dairy products) may inhibit iron absorption (187).
  • CopperCopper: Iron has been found to inhibit the uptake of copper, and vice versa (188).
  • Gastric acid-reducing agentsGastric acid-reducing agents: Concurrent administration with antacids may reduce iron absorption (162). Clinically significant effects are unlikely with adequate dietary iron intake.
  • IodineIodine: Treatment of iron deficiency with supplemental iron has been shown to improve the efficacy of iodine prophylaxis in regions of endemic goiter (189).
  • Pancreatic enzymesPancreatic enzymes: There is some evidence that pancreatic enzyme supplements, such as Cotazym?, Creon?, Pancrease?, Ultrase?, and Viokase?, may reduce iron absorption and contribute to iron deficiency (178).
  • Phytic acidPhytic acid: In humans, consumption of soy protein with native phytate has been shown to significantly reduce transferrin saturation and serum ferritin (190).
  • PolyphenolsPolyphenols: In humans, polyphenols, found in nuts, have shown to markedly inhibit the absorption of nonheme iron. This effect was overcome by 50mg of vitamin C (191).
  • RiboflavinRiboflavin: Riboflavin (vitamin B2) supplements may improve the hematological response to iron supplements in some people with anemia (184). Further details are unavailable.
  • SeleniumSelenium: According to preliminary data, iron may decrease selenium levels (192). Further research is needed to confirm these results.
  • SoySoy: In humans, consumption of soy protein with native phytate has been shown to significantly reduce transferrin saturation and serum ferritin (190).
  • Vitamin AVitamin A: Some evidence suggests that concomitant vitamin A intake may enhance the response to iron supplements (193; 184; 194), possibly by increasing iron absorption (195). Iron and zinc supplementation have also been shown to improve vitamin A status in children (196). Nonetheless, other evidence suggests that iron supplementation may induce vitamin A deficiency (197). The lack of consistent data warrants further research on this topic.
  • ZincZinc: Joint supplementation with iron and zinc has been shown to be less efficacious than supplementing each agent alone (198; 82; 199). Evidence suggests that iron supplementation in pregnancy may reduce serum zinc levels (153). However, in iron-replete women, iron supplementation increases zinc absorption later in pregnancy (154). Supplementing iron in ileostomy patients has also been shown to inhibit zinc absorption (200). Theoretically, zinc supplementation may inhibit iron transport via decreased copper absorption (201).

    • Iron/Food Interactions:

  • Black teaBlack tea: Evidence suggests that black tea has no effects on iron status in people without risk for anemia, but it could potentially affect iron levels in anemic populations (186).
  • Dairy productsDairy products: Human studies have shown that calcium (from calcium salts or dairy products) may inhibit iron absorption (187). Lactoferrin, a major protein component of human milk, has been found to bind iron with high affinity (202).
  • GrainsGrains: In human research, phytic acid, found in grains and legumes, may reduce serum iron levels (190).
  • LegumesLegumes: In human research, phytic acid, found in grains and legumes, may reduce serum iron levels (190).
  • NutsNuts: In human research, polyphenols found in nuts have shown to markedly inhibit the absorption of nonheme iron. This effect was overcome by 50mg of vitamin C (191).
  • SoySoy: In humans, soy proteins may reduce serum iron levels (190).

    • Iron/Lab Interactions:

  • Insufficient available evidence.