Loading Calculator...
Please wait a moment
Please wait a moment
Calculate iron supplementation needs based on your status
Iron supplements should only be taken when iron deficiency is confirmed. Excess iron can be harmful and accumulate in organs. Always test your iron levels (ferritin) before starting supplements, especially men and post-menopausal women. Keep iron supplements away from children.
| Form | Elemental Iron | Absorption | Notes |
|---|---|---|---|
| Ferrous sulfate 325mg | 65mg | Good | Most common, cheapest |
| Ferrous gluconate 325mg | 38mg | Good | Gentler on stomach |
| Ferrous fumarate 325mg | 106mg | Good | Highest elemental iron |
| Iron bisglycinate | Varies | Excellent | Best tolerated |
| Polysaccharide iron | 150mg | Moderate | Slow release, gentle |
Elemental iron is the actual amount of iron available for absorption. Doses refer to elemental iron.
Pair with vitamin C to improve absorption
Iron supplements can slow gut motility and harden stools. To minimize this: take with vitamin C, try every-other-day dosing, increase fiber and water intake, or switch to iron bisglycinate which is gentler on the GI system.
Iron is best absorbed on an empty stomach (1 hour before or 2 hours after meals). However, if it causes stomach upset, take it with a small amount of food (not dairy). Avoid taking with coffee, tea, or calcium supplements - wait at least 2 hours.
If your multivitamin contains calcium (which most do), the calcium will reduce iron absorption. It's better to take iron supplements separately, at least 2 hours apart from calcium-containing supplements or meals.
This is normal! Iron supplements commonly cause dark green or black stools due to unabsorbed iron. However, if you have tarry black stools (different texture) or signs of bleeding, contact your doctor immediately.
For iron deficiency anemia, typically 3-6 months to replete stores, followed by 3 months after hemoglobin normalizes. Your doctor should recheck your ferritin to ensure adequate repletion. Don't continue indefinitely without monitoring.
Plant-based (non-heme) iron is absorbed at only 2-20% vs 15-35% for heme iron from meat. Vegetarians and vegans should aim for 1.8× the RDA and combine iron-rich foods with vitamin C sources to enhance absorption. Avoid tea/coffee with iron-rich meals.
Iron supplementation should be based on confirmed iron deficiency through blood testing. Taking iron supplements without deficiency can lead to iron overload, especially in men and people with hemochromatosis. Always consult a healthcare provider before starting iron supplements. Keep iron supplements out of reach of children - accidental overdose is a medical emergency.