Iron Supplements: When & How to Take (plus Types of Iron)

Updated in December 2023

Iron supplements can be taken to prevent iron deficiency anemia in populations who require higher amounts of iron, like babies, children, pregnant or breastfeeding women.

In addition, iron supplements are also prescribed to prevent or treat anemia in people who have difficulties absorbing iron or who have a high need for this mineral, such as in cases of chronic kidney disease, burns, some types of cancer and women with heavy periods.

Iron supplementation can be done with the use of tablets, syrups, oral capsules or injections. Dosages and length of treatment vary according to the patient's age and the underlying cause. You should only take iron supplements if recommended by a doctor or registered dietitian.

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When to take

Iron supplements can be prescribed to prevent iron deficiency in people who are at high risk of iron deficiency anemia, such as babies, children, pregnant women and breastfeeding women.

Iron supplements can also be prescribed to prevent or treat anemia in people who have a low-iron diet, or who have difficulties absorbing. Certain health conditions can also require a higher iron intake to promote recovery, such as:

  • Chronic kidney disease
  • Some types of cancer
  • Excessive bleeding during menstruation or after childbirth
  • Burns
  • Verminosis
  • Bleeding
  • Bariatric surgery

Iron supplementation varies according to the patient's age, the underlying cause of low iron and the severity of the anemia. Therefore, it should only be taken as prescribed by a doctor.

How to take

The use of iron supplements varies according to a person's age, and the causes and severity of anemia. However, the dosage of iron supplements for the treatment of iron deficiency anemia is generally as follows:

  • Children: 3 to 6 mg per kg of body weight per day
  • Pregnant women: 60 to 120 mg of iron combined with 400 mg of folic acid per day
  • Adults: 120 mg per day
  • Elderly: 15 mg of iron per day

The use of oral iron supplements for the treatment of anemia typically lasts around 6 months. It usually terminates when hemoglobin levels are within normal ranges. Treatment of anemia with injections is done 1 to 3 times a week.

Iron supplements should preferably be taken 1 hour before or 2 hours after meals, because the phosphates, phytates and tannins present in some foods can block iron absorption. It should also not be taken together with antibiotic medicines, antacids, milk and dairy products or caffeinated drinks such as coffee, black tea or yerba mate tea.

Acidic foods improve iron absorption, and therefore you can take this supplement with 1/2 glass of orange juice, lemonade, passion fruit juice, cherry juice or cashew milk.

Types of iron supplements

Elemental iron is unstable and oxidizes easily, which is why it is usually found in compounded forms, such as ferrous sulphate or ferrous gluconate, for example, These help to keep the iron more stable. Iron supplements can also be found in combination with vitamins such as folic acid and vitamin B12.

The iron supplements most commonly used to prevent and combat anemia include:

  • Ferrous sulphate
  • Chelated iron
  • Ferrous gluconate
  • Ferrous fumarate

Ferric hydroxide saccharate is an iron supplement that is injected and typically recommended for those who are unable to tolerate oral iron supplements. They are also prescribed for cases of severe anemia, or patients on hemodialysis or chemotherapy.

Possible side effects

Taking iron supplements can cause symptoms such as a metallic taste in the mouth, heartburn, nausea, loss of appetite, vomiting, diarrhea or constipation.

Nausea and gastric discomfort can increasing depending on the dose you are taking. These symptoms are usually felt 30 to 60 minutes after taking the supplement, but tend to disappear within the first 3 days of treatment.

To reduce constipation caused by the iron supplement, it is advisable to increase your intake of fiber. You should increase your intake of fruits, vegetables, whole grains and legumes. Increasing your daily water intake also helps to prevent constipation.

Contraindications for use

Iron supplementation is not indicated for people with conditions that prevent iron absorption or conditions that lead to high iron levels, such as thalassemia, sickle cell anemia, hemolytic anemia or hemochromatosis.

This supplement is also not suitable for people with gastric ulcers, chronic diarrhea and ulcerative colitis.