Iron deficiency
Symptoms, at-risk groups, and clinical context for iron deficiency. Sourced from NIH Office of Dietary Supplements and StatPearls.
Iron deficiency is the world's most common nutritional deficiency, affecting an estimated 25% of the global population. In the US, it's most common in menstruating women, pregnant women, infants, and people with GI bleeding. Iron deficiency anemia develops when stored iron runs out and red blood cell production is impaired.
Common symptoms
- Fatigue and decreased exercise tolerance
- Pale skin, especially inside the lower eyelid
- Shortness of breath with exertion
- Cold hands and feet
- Brittle or spoon-shaped nails
- Hair thinning or hair loss
- Restless legs syndrome (especially at night)
- Pica — unusual cravings for ice, dirt, or starch
- Headaches and lightheadedness
At-risk groups
- Menstruating women, especially those with heavy periods
- Pregnant women (iron requirements nearly double)
- Infants and toddlers, especially those weaned to cow's milk early
- Adolescents during growth spurts
- Vegetarians and vegans (plant iron is less bioavailable than heme iron)
- Endurance athletes (foot-strike hemolysis, sweat losses)
- People with GI conditions causing chronic blood loss (ulcers, IBD, colon cancer)
- Frequent blood donors
- People who've had bariatric surgery
When to see a doctor: Persistent fatigue with any combination of pale skin, shortness of breath, hair thinning, or unusual cravings warrants a CBC plus ferritin test. Important: do NOT begin iron supplementation without testing first — iron overload can cause organ damage, and iron supplements interact with many medications.
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Related deficiencies
Nutrients with overlapping symptoms — useful when investigating an unclear clinical picture.