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Research · Medication

Iron infusions

Against oral iron, infusions raised hemoglobin and ferritin more in kidney disease, bowel disease and pregnancy. In heart failure with iron deficiency they cut hospital admissions against placebo without lowering all-cause deaths. Before abdominal surgery they did not cut transfusions in the largest trial. Ferric carboxymaltose caused low phosphate in about half of people. Anaphylaxis was rare.

Add to Bio HackChecked 2026-11-14
Status
Prescription drugs in the US, given into a vein (INFeD can also be injected into a muscle). Injectafer is FDA-approved for iron deficiency anemia in people 1 year and older who cannot take or did not respond to oral iron, in non-dialysis chronic kidney disease, and for iron deficiency in heart failure (NYHA class II or III) to improve exercise capacity. Venofer is approved for iron deficiency anemia in chronic kidney disease. Feraheme and Monoferric are approved for iron deficiency anemia in adults who cannot take or did not respond to oral iron, or who have chronic kidney disease. INFeD is approved for iron deficiency not treatable with oral iron, from 4 months of age. Injectafer carries an FDA boxed warning for symptomatic low phosphate, and Feraheme and INFeD carry boxed warnings for anaphylaxis.
Also called
intravenous iron, IV iron, iron infusion, ferric carboxymaltose, Injectafer, iron sucrose, Venofer, ferumoxytol, Feraheme, ferric derisomaltose, iron isomaltoside, Monoferric, low-molecular-weight iron dextran, iron dextran, INFeD, parenteral iron
Taken for
iron deficiency anemia, low ferritin, low iron, heart failure with iron deficiency, anemia in pregnancy, postpartum anemia, anemia before surgery, anemia in kidney disease, restless legs, fatigue, exercise performance

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help7

Reported risks13

What people take it for, and what was found

Shown to help7

StrongVery common

Hemoglobin and iron stores, against oral iron

Shown to raise hemoglobin, ferritin and transferrin saturation more than oral iron, in kidney disease, bowel disease and other causes of iron deficiency anemia.

Compared with oral iron [1][2][3]; oral iron or no iron [4]

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
In chronic kidney disease, intravenous iron raised hemoglobin 0.72 g/dL more than oral iron (95% CI 0.39 to 1.05, 31 studies), ferritin by 224.84 µg/L more and transferrin saturation by 7.69% more. Target hemoglobin was reached by 542 per 1,000 on intravenous iron against 317 per 1,000 on oral iron (RR 1.71, 95% CI 1.43 to 2.04), and the dose of erythropoiesis-stimulating agents fell (SMD -0.72). Deaths (RR 1.12, 95% CI 0.64 to 1.94) and the need to start dialysis did not differ [1]. In inflammatory bowel disease, a hemoglobin rise of 2.0 g/dL or more was more likely on intravenous iron (OR 1.57, 95% CI 1.13 to 2.18), and stopping treatment for side effects or intolerance was less likely (OR 0.27, 95% CI 0.13 to 0.59) [2]. Across 154 trials in all patient groups, hemoglobin rose 0.57 g/dL more than on oral iron or no iron (95% CI 0.50 to 0.64) [4]. A 2025 review of 31 studies found larger hemoglobin rises on intravenous iron in kidney disease, bowel disease, cancer-related anemia and general iron deficiency anemia, and no difference after surgery [3].
Population
39 studies with 3,852 adults and children with chronic kidney disease [1]; 5 RCTs with 694 adults with inflammatory bowel disease [2]; 154 RCTs with 32,920 participants [4]; 31 studies across conditions [3].
Sources
[1], [2], [4], [3]
Caveats
Certainty was low in the kidney review, all its trials were open-label, and follow-up was short [1]. Bowel disease trials were not blinded [2]. Heterogeneity for hemoglobin was very high (I² 94%) [4][3]. A higher lab number is not the same as feeling better: quality of life rarely differed [1].
Strong

Heart failure admissions and cardiovascular death

Shown to lower heart failure hospital admissions and cardiovascular death combined by about 20 to 28% against placebo in heart failure with iron deficiency.

Compared with placebo [5][6]; placebo or standard care [7][8][9]

The numbers and sources
Effect
Pooling FAIR-HF, CONFIRM-HF, AFFIRM-AHF, IRONMAN, HEART-FID and FAIR-HF2, intravenous iron lowered recurrent heart failure admissions and cardiovascular death against placebo at 12 months (RR 0.72, 95% CI 0.55 to 0.89) and over full follow-up (RR 0.81, 95% CI 0.63 to 0.97). Recurrent admissions alone fell (RR 0.78 over full follow-up). The effect was largest in the first year [5]. A review of 14 trials found fewer total heart failure admissions (rate ratio 0.739, 95% CI 0.661 to 0.827) and fewer combined cardiovascular deaths and admissions (OR 0.838) [6]. Two more reviews of 14 trials agreed (OR 0.73, 95% CI 0.58 to 0.92 [7]; RR 0.82, 95% CI 0.72 to 0.92 [8]). Restricted to ferric carboxymaltose, 11 trials found a 27% lower rate at 1 year (RR 0.73, 95% CI 0.62 to 0.85) [9].
Population
7,175 patients in 6 trials, mostly men, mean or median age 67 to 74 [5]; 6,624 patients in 14 RCTs [6]; 6,651 patients in 14 RCTs [7]; 7,786 participants in 14 trials [8]; 6,493 patients in 11 RCTs, mean ejection fraction 33.7% [9].
Sources
[5], [6], [7], [8], [9]
Caveats
Five of the six main trials used ferric carboxymaltose and IRONMAN used ferric derisomaltose [5]. IRONMAN was open-label. The reviews pool largely the same trials. Benefit may be larger with transferrin saturation below 20% [6][8].
Strong

Exercise capacity in heart failure

Shown to raise six-minute walk distance by about 19 to 29 meters against control in heart failure with iron deficiency.

Compared with placebo or standard care [8][9]

The numbers and sources
Effect
Intravenous iron raised six-minute walk distance by 18.99 m (95% CI 7.41 to 30.57) [8]. Ferric carboxymaltose raised it by 29.19 m (95% CI 11.95 to 46.43) [9].
Population
14 trials with 7,786 participants [8]; 11 RCTs with 6,493 patients [9].
Sources
[8], [9]
Caveats
Walk distance was not measured in every trial. Exercise capacity in heart failure is the use Injectafer is approved for [10].
StrongStudied in pregnancy

Anemia in pregnancy, against oral iron

Shown to raise maternal hemoglobin about 0.6 g/dL more than oral iron by delivery in pregnant women with iron deficiency anemia, with fewer transfusions in one of two reviews.

Compared with oral iron [11][12]

The numbers and sources
Effect
Across 29 RCTs, intravenous iron gave higher maternal hemoglobin at delivery (WMD 0.59 g/dL, 95% CI 0.31 to 0.87), higher maternal ferritin (WMD 50.93 ng/mL) and higher newborn ferritin (WMD 21.38 ng/mL). Blood transfusion during the delivery stay was 37% less common (RR 0.63, 95% CI 0.49 to 0.82), mostly when pretreatment hemoglobin was 9 g/dL or less. Mild side effects were 43% less common, and no serious adverse events were reported [11]. An earlier review of 15 RCTs rated the evidence for fewer transfusions low quality (Peto OR 0.19, 95% CI 0.05 to 0.78, number needed to treat 95) and found no strong evidence that intravenous iron as a first treatment improved clinical outcomes [12].
Population
29 RCTs with 11,771 pregnant women [11]; 15 RCTs with 1,938 pregnant women, 10 in low or middle income countries [12].
Sources
[11], [12]
Caveats
Every trial in [12] had a high risk of bias in at least one area. One trial in the original 2018 review was retracted [11].
ModerateStudied in women

Postpartum anemia, against oral iron

Shown to raise hemoglobin about 0.9 g/dL more than oral iron at 6 weeks after birth in women with postpartum anemia, with less constipation and more flushing.

Compared with oral iron [14]

The numbers and sources
Effect
Hemoglobin at 6 weeks was 0.9 g/dL higher on intravenous iron (95% CI 0.4 to 1.3), and ferritin was higher at weeks 1, 2, 4 and 6. Flushing was more likely (OR 6.95, 95% CI 1.56 to 31.03), and constipation (OR 0.08) and indigestion (OR 0.07) less likely. Anaphylaxis was reported in 0.6% of women given intravenous iron [14].
Population
15 RCTs with 1,001 women on oral iron and 1,181 on intravenous iron, hemoglobin below 12 g/dL after birth [14].
Sources
[14]
Caveats
Only 4 of the 15 trials reported the 6-week hemoglobin [14].
Limited

Heart attack, stroke and death on dialysis, higher against lower doses

One trial found fewer heart attacks, strokes, heart failure admissions and deaths with proactive high-dose iron sucrose than with reactive low-dose iron sucrose in people on hemodialysis.

Compared with reactive low-dose intravenous iron sucrose [17]

The numbers and sources
Effect
Over a median 2.1 years, 29.3% on proactive high-dose iron sucrose (400 mg a month unless ferritin or transferrin saturation was high) and 32.3% on reactive low-dose dosing had a nonfatal heart attack, nonfatal stroke, heart failure admission or death (HR 0.85, 95% CI 0.73 to 1.00). Recurrent events were fewer (rate ratio 0.77). The high-dose group needed less erythropoiesis-stimulating agent, and infection rates were the same [17].
Population
2,141 adults on maintenance hemodialysis in the UK [17].
Sources
[17]
Caveats
Open-label with blinded end-point review. Both groups received intravenous iron, so this compares doses, not iron against none [17].
Why limited
This rests on one trial, of 2,141 people. Strength counts independent studies that agree, so one trial is limited at any size.
Strong

Restless legs

Shown to lower restless legs severity about 6 points against placebo with intravenous ferric carboxymaltose. One small trial found no difference from oral iron.

Compared with placebo [18][19]; oral ferrous sulfate [20]

The numbers and sources
Effect
Pooling 7 studies, intravenous ferric carboxymaltose lowered the International Restless Legs Scale score by 5.77 points (95% CI 2.70 to 8.85) and improved visual analog and SF-36 scores against placebo. RLS quality of life scores did not differ. Adverse events, mainly nausea, were more common, and severe events did not differ [18]. A second review of 7 RCTs found a 6.03-point drop (95% CI 1.96 to 10.11) [19]. In a double-blind pilot trial in iron deficiency anemia, intravenous ferumoxytol and oral ferrous sulfate both improved symptoms, with no significant difference at 6 weeks [20].
Population
539 participants in 7 studies [18]; 537 patients in 7 RCTs [19]; patients with restless legs and iron deficiency anemia [20].
Sources
[18], [19], [20]
Caveats
The two reviews pool largely the same trials [18][19]. The pilot trial lost final data for 30 patients during COVID-19 and recruited more [20]. Findings that pool oral and intravenous iron are on the iron page.

Mixed results2

Moderate

Blood transfusion around surgery

Mixed results: the largest trial found no drop in transfusion or death before abdominal surgery, while a review of 10 trials found 16% fewer transfusions.

Compared with placebo saline infusion [15]; placebo or oral iron [16]

The numbers and sources
Effect
In PREVENTT, a single 1,000 mg infusion of ferric carboxymaltose 10 to 42 days before major open abdominal surgery did not lower death or transfusion against placebo, 29% against 28% (RR 1.03, 95% CI 0.78 to 1.37), nor the number of transfusions (rate ratio 0.98) [15]. Pooling 10 RCTs, preoperative intravenous iron lowered transfusion (RR 0.84, 95% CI 0.71 to 0.99) and raised hemoglobin 7.15 g/L before surgery, with no rise in serious adverse effects [16].
Population
487 anemic adults at 46 UK centers [15]; 1,039 participants in 10 RCTs before major surgery [16].
Sources
[15], [16]
Caveats
Some trials in [16] had a high risk of bias. PREVENTT was double-blind [15].
LimitedStudied in women

Fatigue and exercise in active women with low iron and no anemia

One small trial found less fatigue and better running economy at 4 weeks after an iron infusion, with no change in VO2 peak, in active women without anemia.

Compared with placebo infusion [21]

The numbers and sources
Effect
Intravenous iron raised serum ferritin, serum iron and transferrin saturation, with highly variable responses. VO2 peak, lactate threshold and hemoglobin mass did not differ from placebo. Running economy and fatigue scores improved on iron at 4 weeks. Mood and quality of life did not change [21].
Population
26 recreationally active women of reproductive age with iron deficiency without anemia [21].
Sources
[21]
Caveats
One small trial with 4 weeks of follow-up. One author reported fees and grants from iron makers [21].

Not shown to help2

Strong

Death in heart failure

Not shown to lower death from any cause in heart failure with iron deficiency. Reviews disagree on whether cardiovascular death fell.

Compared with placebo [5][6]; placebo or standard care [7][8]

The numbers and sources
Effect
All-cause mortality did not differ from placebo over full follow-up (HR 0.92, 95% CI 0.80 to 1.07), nor did cardiovascular mortality (HR 0.87, 95% CI 0.73 to 1.04) [5]. One-year all-cause mortality did not differ in another review (OR 0.85, 95% CI 0.71 to 1.02), with a trend for cardiovascular mortality (OR 0.88, 95% CI 0.76 to 1.01) [7]. Two other reviews found lower cardiovascular death (OR 0.867, 95% CI 0.755 to 0.955 [6]; OR 0.86, 95% CI 0.76 to 0.98 [8]), and one of them found no drop in all-cause mortality (OR 0.93, 95% CI 0.83 to 1.04) [8].
Population
As in the block above [5][6][7][8].
Sources
[5], [6], [7], [8]
Caveats
The reviews overlap heavily and used different statistical models.
ModerateStudied in pregnancy

Newborn outcomes after iron infusion in pregnancy

Not shown to change preterm birth, stillbirth or newborn death against oral iron in pregnancy.

Compared with oral iron [13]

The numbers and sources
Effect
Preterm birth did not differ (RR 0.96, 95% CI 0.86 to 1.07, 7 studies, 8,431 pregnancies, moderate certainty), nor did stillbirth (RR 0.85, 95% CI 0.64 to 1.13) or newborn death (2.0% against 2.3%, RR 0.90, 95% CI 0.66 to 1.22). Cord blood ferritin was slightly higher after intravenous iron (19 µg/L) [13].
Population
15 RCTs in pregnant women [13].
Sources
[13]
Caveats
Stillbirth and newborn death were low-certainty evidence [13].

Doses studied

Injectafer's label uses 750 mg of ferric carboxymaltose into a vein in two doses at least 7 days apart (1,500 mg a course) for patients 50 kg or more, or one dose of 15 mg/kg up to 1,000 mg in adults. In heart failure the label gives 500 to 1,000 mg on day 1 and at week 6 by hemoglobin and weight, then 500 mg at weeks 12, 24 and 36 if iron stays low [10]. PREVENTT used one 1,000 mg ferric carboxymaltose infusion over 15 minutes [15]. The PHOSPHARE trials compared one 1,000 mg dose of ferric derisomaltose with ferric carboxymaltose 750 mg on days 0 and 7 [22]. Feraheme's trials used two 510 mg doses of ferumoxytol, mostly 3 to 8 days apart, and the label now requires an infusion over at least 15 minutes [23]. PIVOTAL gave iron sucrose 400 mg a month, held when ferritin was above 700 µg/L or transferrin saturation 40% or more, against 0 to 400 mg a month given when ferritin fell below 200 µg/L or saturation below 20% [17]. INFeD requires a test dose before the first full dose, into a vein or a muscle [24].

Risks

Reported risks12

ModerateVery common

FDA boxed warning: severe low phosphate after ferric carboxymaltose

The label warns that Injectafer can cause severe, prolonged low phosphate, with hospitalization, bone softening and fractures, including in people with normal phosphate beforehand.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
FDA added a boxed warning in August 2026. The label states symptomatic low phosphate, including severe cases with osteomalacia and fractures needing treatment, occurred after single and repeated doses after approval. It names risk factors (bowel disease, malabsorption, low vitamin D, overactive parathyroid, malnutrition, hereditary hemorrhagic telangiectasia), and people without them were also affected. Most cases resolved within 3 months. In the trials, low phosphate was reported as an adverse reaction in 2.1% on Injectafer against 0.1% on pooled comparators, and blood phosphorus fell below 2 mg/dL in 27% (440 of 1,638) [10].
Population
1,775 adults on Injectafer and 1,783 on oral iron or other intravenous iron in two randomized trials, plus reports after approval [10].
Sources
[10]
Caveats
The fractures and bone softening come from reports after approval, with no denominator. The 27% is a lab value, not symptoms [10].
StrongVery common

Low phosphate: ferric carboxymaltose against ferric derisomaltose and ferumoxytol

Shown to cause low phosphate in about half of people after ferric carboxymaltose, against about 4 to 8% after ferric derisomaltose.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Across 42 trials, low phosphate occurred in 47% after ferric carboxymaltose (95% CI 36 to 58%) and 4% after ferric derisomaltose (95% CI 2 to 5%), and lasted to the end of study (up to 3 months) in up to 45% of those on ferric carboxymaltose. Lower ferritin and transferrin saturation and normal kidney function predicted it [25]. In the two PHOSPHARE trials, low phosphate by day 35 occurred in 75.0% and 73.7% after ferric carboxymaltose against 7.9% and 8.1% after ferric derisomaltose [22]. Pooling 3 RCTs, ferric carboxymaltose carried 8.37 times the risk (95% CI 5.10 to 13.75), and severe low phosphate occurred in 11.3% on it and in none on ferric derisomaltose [26]. In a trial against ferumoxytol, severe low phosphate at week 2 occurred in 38.7% on ferric carboxymaltose and 0.4% on ferumoxytol [23].
Population
42 prospective trials [25]; 245 adults with iron deficiency anemia, about 95% women, normal kidney function [22]; 3 RCTs with 364 participants and 18 other studies [26]; 1,997 adults with iron deficiency anemia [23].
Sources
[25], [22], [26], [23]
Caveats
The PHOSPHARE trials were open-label [22]. Low phosphate is a lab finding, and symptoms were not measured in every trial.
StrongCommon

Severe infusion and allergic reactions, against comparators

Shown to raise severe infusion reactions about 2.5 to 3.6 times against oral iron or other comparators, about 24 per 1,000 against 7 per 1,000 in kidney disease.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Across 103 trials against oral iron, no iron, placebo or intramuscular iron, severe infusion reactions were more common with intravenous iron (RR 2.47, 95% CI 1.43 to 4.28), with no rise in serious adverse events overall (RR 1.04, 95% CI 0.93 to 1.17) [29]. In kidney disease, allergic reactions or low blood pressure affected 24 per 1,000 on intravenous iron against 7 per 1,000 on oral iron (RR 3.56, 95% CI 1.88 to 6.74, low certainty) [1].
Population
10,390 patients on intravenous iron and 8,863 on comparators in 103 trials up to 2013 [29]; 2,607 participants with chronic kidney disease in 15 studies [1].
Sources
[29], [1]
Caveats
Adverse effects were reported in only half of the kidney trials [1]. The 2015 review includes older products no longer sold [29].
ModerateCommon

Nausea, flushing and other common reactions

Shown to cause nausea in about 7% and flushing in about 4% after ferric carboxymaltose, against 2% and 0.2% on comparators.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
In two randomized trials, nausea occurred in 7.2% on Injectafer against 2% on pooled comparators and 1.2% on oral iron, flushing in 4% against 0.2%, redness in 3% against 0.6%, dizziness in 2.1% against 1.3%, vomiting in 2% against 1%, and brown skin staining at the injection site in 1.4% against 0.3% [10]. On Feraheme, headache occurred in 3.4% and nausea in 1.8%, against 3.1% and 3.4% on ferric carboxymaltose [23].
Population
1,775 adults on Injectafer, 1,783 on comparators [10]; 997 on Feraheme and 1,000 on ferric carboxymaltose [23].
Sources
[10], [23]
Caveats
Comparators mixed oral iron and other intravenous products [10].
ModerateCommon

Raised blood pressure after ferric carboxymaltose

Shown to raise blood pressure in about 4% after ferric carboxymaltose against 2% on comparators, usually right after the dose.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Hypertension was reported in 4% on Injectafer against 2% on pooled comparators and 0.4% on oral iron. Brief rises in systolic pressure, sometimes with flushing, dizziness or nausea, occurred in 6% and mostly resolved within 30 minutes [10].
Population
1,775 adults on Injectafer in two randomized trials [10].
Sources
[10]
Caveats
Label data from the maker's trials [10].
ModerateCommon

Raised liver enzymes after ferric carboxymaltose

Shown to raise ALT or AST in 1.2% after ferric carboxymaltose against 0.2% on comparators.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Raised hepatic enzymes, grouping ALT and AST increases, were reported in 1.2% on Injectafer against 0.2% on pooled comparators and 0% on oral iron [10].
Population
1,775 adults on Injectafer in two randomized trials [10].
Sources
[10]
Caveats
The label does not give the size of the rises [10].
ModerateUncommon

FDA boxed warning: anaphylaxis with ferumoxytol

The label warns of fatal and serious allergic reactions, including anaphylaxis, with Feraheme, even after an earlier dose was tolerated. Trial rates were 0.2 to 0.4%.

The numbers and sources
How common
Uncommon: between 1 in 1,000 and 1 in 100 people.
Effect
Allergic reactions occurred in 0.4% (4 of 997) given Feraheme as a 15-minute infusion, and serious ones in 0.2% (4 of 1,806) given it as the older rapid injection. Symptoms can begin with low blood pressure, fainting, unresponsiveness or cardiac arrest. Moderate to severe allergic reactions or low blood pressure occurred in 0.6% on Feraheme and 0.7% on ferric carboxymaltose in a head-to-head trial [23].
Population
997 adults with iron deficiency anemia of any cause, and 1,806 mostly with chronic kidney disease [23].
Sources
[23]
Caveats
The label requires infusion over at least 15 minutes with treatment for anaphylaxis on hand and 30 minutes of observation [23].
LimitedRare

Anaphylaxis rates by product

Linked to anaphylaxis after about 1 to 10 per 10,000 first doses in older US adults, highest with iron dextran and ferumoxytol and lowest with ferric carboxymaltose and iron sucrose.

The numbers and sources
How common
Rare: fewer than 1 in 1,000 people.
Effect
Per 10,000 first doses, adjusted anaphylaxis rates were 9.8 for iron dextran, 4.0 for ferumoxytol, 1.5 for ferric gluconate, 1.2 for iron sucrose and 0.8 for ferric carboxymaltose. Against iron sucrose the odds were 8.3 times for iron dextran (95% CI 3.5 to 19.8) and 3.4 times for ferumoxytol (95% CI 1.4 to 8.3). Low-molecular-weight iron dextran alone kept a higher risk (OR 8.4). Anaphylaxis needing hospital care occurred only with iron dextran or ferumoxytol [27]. In five European countries, anaphylaxis followed 0.4 to 0.5 per 10,000 first treatments [28].
Population
US Medicare patients receiving a first dose of intravenous iron, 2013 to 2018 [27]; 304,210 new users in Europe, 1999 to 2017 [28].
Sources
[27], [28]
Caveats
Observational studies. The European study captured few hospital treatments and could not compare dextran with other products [28]. Results in Medicare may not apply to younger people [27].
LimitedHow often is not known

FDA boxed warning: anaphylaxis with iron dextran

The label warns of anaphylactic-type reactions with INFeD, including deaths, some after a test dose and some after a test dose was tolerated.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The label states fatal reactions followed the test dose of iron dextran and also occurred when the test dose was tolerated, and that people with multiple drug allergies may be at higher risk. It requires a test dose and resuscitation equipment on hand [24].
Population
People given iron dextran into a vein or a muscle [24].
Sources
[24]
Caveats
The label gives no rate. Comparative rates are in the next block.
LimitedHow often is not known

Use in pregnancy

The labels warn that a severe allergic reaction to an iron infusion in pregnancy can slow the baby's heart rate, especially in the second and third trimester.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The Injectafer and Feraheme labels state severe reactions such as shock may cause fetal bradycardia, and that data are too few to assess birth defects or miscarriage. Ferric carboxymaltose and ferumoxytol caused fetal malformations in rabbits at doses toxic to the mother [10][23]. The Venofer label states published studies of iron sucrose after the first trimester have not shown harm to mother or fetus, and first-trimester data are too few [30]. The Monoferric label states published data have not identified a risk of birth defects or miscarriage [31].
Population
Pregnant women in published reports and reports after approval, and pregnant rabbits [10][23][30][31].
Sources
[10], [23], [30], [31]
Caveats
Pregnancy trials comparing infusions with pills are in the outcome blocks above.
LimitedHow often is not known

MRI interference after ferumoxytol

The label warns that Feraheme can alter MRI scans for up to 3 months after the last dose.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The label states ferumoxytol may change MRI images for up to 3 months, with the largest effect on vascular images in the first 1 to 2 days. It does not affect X-ray, CT, PET, ultrasound or nuclear medicine scans [23].
Population
People given Feraheme [23].
Sources
[23]
Caveats
A label statement, not a trial result.
LimitedHow often is not known

Interactions with oral iron and ACE inhibitors

The labels state iron sucrose and ferumoxytol may reduce absorption of iron pills, and ACE inhibitors may raise the risk of anaphylactic-type reactions to iron dextran.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The Venofer and Feraheme labels state they may reduce absorption of oral iron taken at the same time [30][23]. The INFeD label states drug interactions have not been studied, that ACE inhibitors may increase the risk of anaphylactic-type reactions, and that iron dextran may falsely raise bilirubin and falsely lower calcium on lab tests [24].
Population
Label statements [30][23][24].
Sources
[30], [23], [24]
Caveats
No interaction studies were done [23][24].

Mixed results1

ModerateHow often is not known

Infections

Mixed results: one review of 154 trials found about 17% more infections against oral or no iron, while other reviews and trials found no increase.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Across 154 RCTs, infection was more common with intravenous iron (RR 1.17, 95% CI 1.04 to 1.31, moderate certainty), with no effect on mortality or hospital stay [4]. A review of 103 trials against oral iron, no iron, placebo or intramuscular iron found no increase in infections [29]. In heart failure trials, infection rates were similar to placebo (OR 1.02, 95% CI 0.66 to 1.59) [5]. In hemodialysis, high-dose and low-dose iron sucrose had the same infection rate [17].
Population
32,920 participants [4]; 103 trials [29]; 7,175 heart failure patients [5]; 2,141 people on hemodialysis [17].
Sources
[4], [29], [5], [17]
Caveats
Trials defined infection in different ways [4].

Checked, no increase found1

Strong

Gut side effects, against oral iron

Gut side effects were about half as common on intravenous iron as on oral iron, 150 against 319 per 1,000 in kidney disease.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In kidney disease, gut side effects affected 150 per 1,000 on intravenous iron and 319 per 1,000 on oral iron (RR 0.47, 95% CI 0.33 to 0.66) [1]. In bowel disease, gut adverse events were consistently lower on intravenous iron [2]. After birth, constipation was less likely on intravenous iron (OR 0.08) [14].
Population
1,986 participants with chronic kidney disease [1]; 694 adults with bowel disease [2]; 2,182 women after birth [14].
Sources
[1], [2], [14]
Caveats
Low-certainty evidence in kidney disease [1]. Gut side effects of iron pills are on the iron page.

Claims tested and not found

  1. That an iron infusion before major abdominal surgery cuts transfusions. In PREVENTT, 1,000 mg of ferric carboxymaltose did not lower death or transfusion against placebo (RR 1.03, 95% CI 0.78 to 1.37) [15].
  2. That intravenous iron lowers deaths in heart failure. All-cause mortality did not differ from placebo over full follow-up (HR 0.92, 95% CI 0.80 to 1.07) [5].
  3. That an iron infusion raises VO2 in active women without anemia. VO2 peak and hemoglobin mass did not differ from placebo at 4 weeks [21].
  4. That infusions in pregnancy improve newborn survival over iron pills. Preterm birth, stillbirth and newborn death did not differ from oral iron [13].

Related

Iron

Sources

  1. O'Lone EL, Hodson EM, Nistor I, Bolignano D, Webster AC, Craig JC. Parenteral versus oral iron therapy for adults and children with chronic kidney disease. Cochrane Database of Systematic Reviews. 2019. https://doi.org/10.1002/14651858.cd007857.pub3
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