Proferrin ES and Proferrin Forte) can be used when regular iron supplements such as ferrous sulfate or ferrous fumarate are not tolerated or absorbed. A clinical study demonstrated that HIP increased serum iron levels 23 times greater than ferrous fumarate on a milligram-per-milligram basis.Another alternative is ferrous glycine sulfate or ferroglycine sulfate, has less gastrointestinal side-effects than standard preparations such as iron fumarate. It is unusual among oral preparations of iron supplements in that the iron in this preparation has very high oral bioavailability, especially in the liquid formulation. This option should be evaluated before resorting to parenteral therapy. It is especially useful in iron deficiency anemia associated with autoimmune gastritis and Helicobacter pylori gastritis, where it generally has satisfactory effect.Since iron stores in the body are generally depleted, and there is a limit to what the body can process (about 2–6 mg/kg of body mass per day; i.e. for a 100 kg/220 lb man this is equal to a maximum dose of 200–600 mg/per day) without iron poisoning, this is a chronic therapy which may take 3–6 months.Due to the frequent intolerance of oral iron and the slow improvement, parenteral iron is recommended in many indications. By injection
Iron therapy (intravenously or intramuscular) is given when therapy by mouth has failed (not tolerated), oral absorption is seriously compromised (by illnesses, or when the person cannot swallow), benefit from oral therapy cannot be expected, or fast improvement is required (for example, prior to elective surgery).
Frequent blood donors
Frequent blood donors may be advised to take iron supplements. Canadian Blood Services recommends discussing "taking iron supplements with your doctor or pharmacist" as "the amount of iron in most multivitamins may not meet your needs and iron supplements may be necessary". The American Red Cross recommends "taking a multivitamin with 18 mg of iron or an iron supplement with 18-38 mg of elemental iron for 60 days after each blood donation, for 120 days after each power red donation or after frequent platelet donations". A 2014 Cochrane Review found that blood donors were less likely to be deferred for low hemoglobin levels if they were taking oral iron supplements, although 29% of those who took them experienced side effects in contrast to the 17% that took a placebo. It is unknown what the long-term effects of iron supplementation for blood donors may be. Side effects
Side effects of therapy with oral iron are most often diarrhea or constipation and epigastric abdominal discomfort. Taken after a meal, side effects decrease, but there is an increased risk of interaction with other substances. Side effects are dose-dependent, and the dose may be adjusted. The patient may notice that their stools become black. This is completely harmless, but patients must be warned about this to avoid unnecessary concern. When iron supplements are given in a liquid form, teeth may reversibly discolor (this can be avoided through the use of a straw). Intramuscular injection can be painful, and brown discoloration may be noticed.