Iron deficiency anemia
First line
Oral iron preparations; antianaemic agents
ATC code: B03AA (Iron bivalent, oral preparations)
Brand names
Slow-FE, Ferro-Sequels, Feosol, Proferrin (heme iron polypeptide)
Iron is incorporated into haem of haemoglobin and myoglobin and into iron-sulphur clusters of the respiratory chain. Ferrous salts (sulfate, bisglycinate, fumarate, gluconate) are absorbed in the duodenum via DMT1 and regulated by hepcidin. Ferric polymaltose releases iron more slowly, causes fewer GI side effects but works more slowly in severe anaemia. Heme iron in hemoglobin polypeptide and bovine lactoferrin use a separate uptake pathway (HCP1) and are less studied in RCTs. Hepcidin suppresses absorption after each dose – this is why current and guidelines favour alternate-day dosing over daily.
First line
Oral iron is first-line for iron-deficiency anaemia. AEMPS and approve all main salts. NG8 2024 and British Society for Haematology 2021 recommend 40-100 mg of elemental iron on alternate days: alternate-day dosing yields the same haemoglobin rise as daily and is better tolerated. Haemoglobin and ferritin are checked at 4-8 weeks. If levels do not rise over 2-3 months a search for the cause (ongoing blood loss, malabsorption) and switch to IV iron are warranted. Of iHerb forms, sulfate is cheaper and most studied; bisglycinate claims better tolerability at comparable bioavailability.
In oral intolerance, severe anaemia (haemoglobin below 70 g/L), inflammatory bowel disease, or late pregnancy with anaemia, intravenous iron is used.
Sources
First line
Iron deficiency prevention in pregnancy. and recommend 30-60 mg of elemental iron daily or alternate-day from the second trimester, especially with low baseline ferritin. SEGO applies a similar regimen in Spain. AEMPS approves Tardyferon and Ferro Sanol for this indication. Self-prescribing high-dose iron without testing is rarely warranted: in patients with HFE mutations (asymptomatic haemochromatosis) iron overload accelerates hepatic damage.
Sources
Individual decision
Iron use in low ferritin without anaemia (endurance athletes, after blood donation, with heavy menstrual bleeding) is decided individually. British Society for Haematology 2021 accepts treatment at ferritin below 30 mcg/L with fatigue symptoms. NIH ODS 2024 states that routine intake in asymptomatic people with normal haemoglobin is unjustified. The dose is set by tolerability – 40-60 mg of elemental iron on alternate days. Ferritin is rechecked at 8-12 weeks. Ferritin and transferrin testing precede a course, not «iron for energy» on Instagram advice.
Sources
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Biohacker blogs and iHerb market iron as «energy for everyone» without ferritin or haemoglobin testing. In people with normal ferritin high-dose iron offers no benefit over placebo and carries risk: 2004 and 2018 highlight iron overload, especially in HFE mutation carriers (around 5% of Spaniards and Russians as heterozygotes, around 0.5% as homozygotes). Overload causes hepatic fibrosis, cardiomyopathy and pancreatic damage (bronze diabetes). Heme iron and lactoferrin on iHerb belong to the same risk category. Fatigue calls for ferritin, haemoglobin, TSH and clinical assessment, not self-prescribed iron. Discuss with a clinician.
Sources
Calcium reduces iron absorption by 40–60% at concurrent doses above 300 mg. Iron and calcium are separated by 2 hours. In long-term therapy with both, timing is planned to different parts of the day.
Ascorbic acid 100–200 mg increases ferrous iron absorption by 10–15% by reducing Fe³⁺ to Fe²⁺. The effect is stronger with concurrent than separated dosing. In guidance, vitamin C is optional with iron therapy – not considered mandatory.
1 pair found. Sorted from critical to minor.
Mechanism
Iron forms non-absorbable chelates with tetracyclines in the gut (as with the doxycycline-calcium pair). Doxycycline bioavailability falls by 50–80%.
Symptoms
Persistent infection symptoms 48–72 hours after antibiotic start, risk of clinical failure.
Management
Take doxycycline 2 hours before or 6 hours after iron supplements. Same interval applies to calcium, magnesium, zinc, and aluminium-containing antacids. If timing separation is impossible (e.g. severe iron deficiency), choose an alternative antibiotic (amoxicillin, a cephalosporin).
Opens the checker prefilled with this drug. Pick the second one from your regimen.
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FDA Category A at usual doses for prevention and treatment of iron deficiency. AEMPS and SEGO permit and encourage use in confirmed deficiency. High doses without indication in non-anaemic pregnant women are unjustified and raise gestational diabetes and pre-eclampsia risk per observational studies.
Compatible. Hale L1. Breast milk iron concentration is regulated and barely depends on maternal intake. eLactancia rates the risk as minimal.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Iron oral (salts: sulfate, bisglycinate, fumarate, gluconate, polymaltose; heme iron polypeptide, lactoferrin) is evaluated for the following indications with varying evidence strength: Iron deficiency anemia (evidence tier A), Iron supplementation in pregnancy (evidence tier A), Iron deficiency without anaemia (evidence tier B). See the full indication matrix with dosing and citations above on this page.
Common side effects of Iron oral (salts: sulfate, bisglycinate, fumarate, gluconate, polymaltose; heme iron polypeptide, lactoferrin) (≥ 1 in 100): Nausea, metallic taste, Constipation, less often diarrhoea, Epigastric pain, Dark stools (normal, not melaena), Tooth staining with liquid formulations. See the Safety section for uncommon and serious reactions.
FDA category A. FDA Category A at usual doses for prevention and treatment of iron deficiency. AEMPS and SEGO permit and encourage use in confirmed deficiency. High doses without indication in non-anaemic pregnant women are unjustified and raise gestational diabetes and pre-eclampsia risk per observational studies.
Compatible. Hale L1. Breast milk iron concentration is regulated and barely depends on maternal intake. eLactancia rates the risk as minimal.
Iron oral (salts: sulfate, bisglycinate, fumarate, gluconate, polymaltose; heme iron polypeptide, lactoferrin) is contraindicated in: Hypersensitivity to iron or excipients; Haemochromatosis and other iron overload syndromes; Haemolytic anaemias without confirmed iron deficiency; Recurrent blood transfusions (overload risk); Active peptic ulcer and active intestinal bleeding. Full list in the Safety section.
with normal ferritin, iron has no effect on fatigue. Unwarranted use increases oxidative stress. Check ferritin and complete blood count before buying an iron supplement.
safety differences with oral use are minor. Ferrous iron (Sorbifer, Feosol) is more effective at correcting deficiency; ferric forms (Maltofer) irritate the gastrointestinal tract less. The choice is a matter of tolerance.
non-haem iron from plant sources (buckwheat, pomegranate, apples) is absorbed less efficiently than haem iron from animal sources (red meat, liver, shellfish). In established anaemia, dietary correction is adjunctive – iron preparations are the main therapy.