From the Guidelines
Iron supplementation does not directly cause fatigue, but rather, it is used to treat iron deficiency anemia, which is a common cause of fatigue.
Common Side Effects of Iron Supplementation
- The most common side effects of oral iron supplementation are constipation, diarrhea, and nausea, which can indirectly contribute to feelings of fatigue 1.
Iron Supplementation Dosage and Administration
- Typical doses of oral iron supplements are 100-200 mg/day, in divided doses 1.
- Taking iron with 80 mg ascorbic acid on an empty stomach may improve iron absorption 1.
- Alternate day dosing may improve iron resorption and reduce adverse effects 1.
Importance of Iron Supplementation
- Iron supplementation is essential for treating iron deficiency anemia, which can cause extreme fatigue and breathlessness 1.
- Iron deficiency anemia can be diagnosed by simple blood tests and remedied by treatment with iron replacement therapy (IRT) given by mouth or injection 1.
From the Research
Iron Supplementation and Fatigue
- The relationship between iron supplementation and fatigue has been studied in various contexts, including iron-deficiency anaemia and non-anaemic iron deficiency 2, 3, 4, 5, 6.
- A study on patients with gastrointestinal diseases found that anaemia, including iron-deficiency anaemia, can cause fatigue, but iron supplementation was not directly linked to increased fatigue 2.
- A systematic review of randomised controlled trials found that iron supplementation in non-anaemic iron-deficient adults was associated with reduced self-reported fatigue, but not with objective improvements in physical capacity 3.
- Another study on iron-deficient blood donors found that iron supplementation, either intravenous or oral, improved symptoms of fatigue, restless legs syndrome, and sleep quality 4.
- A randomized controlled trial on nonanemic menstruating women with low ferritin levels found that iron supplementation decreased fatigue, as measured by the Current and Past Psychological Scale, and improved hemoglobin and ferritin levels 5.
- A review article on iron deficiency, fatigue, and restless legs syndrome noted that iron supplementation is considered the treatment of choice for iron deficiency, and that oral iron supplementation is often recommended, with intravenous iron treatment indicated if primary attempts are not sufficient or not tolerated 6.
Key Findings
- Iron supplementation may improve fatigue in individuals with iron deficiency, including those with and without anaemia 3, 4, 5.
- The effect of iron supplementation on fatigue may be more pronounced in individuals with non-anaemic iron deficiency 3.
- Iron supplementation can also improve other symptoms, such as restless legs syndrome and sleep quality, in individuals with iron deficiency 4, 6.
- The optimal dose and duration of iron supplementation for improving fatigue and other symptoms are not well established, but doses of 200-1000 mg of elemental iron are commonly recommended 6.