Safety · Supplement
Iron: side effects, safety & interactions
Constipation and GI upset are common; overdose is dangerous, and iron is a leading cause of pediatric poisoning — store
- Overall grade
- Grade A
- Last revised
- 0
- graded outcomes
- 0
- references listed
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What is uncertain
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The evidence in words
Safety profile
Constipation and GI upset are common; overdose is dangerous, and iron is a leading cause of pediatric poisoning — store away from children. Never supplement chronically without confirmed need; hereditary hemochromatosis makes iron actively harmful.
Interactions to respect
Calcium — Calcium blunts iron uptake — split across meals. · Zinc — Competes for absorption — separate. · Levothyroxine — Binds thyroid hormone — separate by 4 hours. · Caffeine — Coffee polyphenols cut non-heme iron ~40% — separate 2 hours.
What Iron is
Iron is the oxygen-carrying metal at the center of hemoglobin. Deficiency (low ferritin, then anemia) is the world's most common nutrient deficiency, especially in menstruating women, endurance athletes, and plant-based eaters. The body has no route to excrete excess, so iron status must be earned, not guessed.
The honest bottom line
Get ferritin tested before you touch it. If low, iron with vitamin C (ideally alternate-day) fixes real fatigue. If normal, skip it — more iron is not more energy.
Related reading
Entries that share this one's tags or conditions.
- IronOnly supplement it against a ferritin number — transformative in deficiency, pro-oxidant and constipating in excess.Evidence grade A
- Iron for Fatigue with low ferritin (non-anemic)Evidence grade B — Benefit when ferritin is lowEvidence grade B
- Iron for Iron-deficiency anemiaEvidence grade A — DefinitionalEvidence grade A
- Iron for Restless legs syndromeEvidence grade B — When iron-deficientEvidence grade B
Sources
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Last revised . A grade is this entry's reading of the evidence, not medical advice.