Take iron the way it actually works.
The right dose, form, and timing matter more than the brand. Every-other-day dosing often absorbs better than daily and causes fewer GI symptoms. Always check the elemental iron number on the label — that's the number that matters.
How to take it
45–65 mg elemental iron per dose for adults.
Once daily — or every other day. EOD may absorb better and cause less nausea.
250–500 mg vitamin C, or a glass of orange juice.
Water or a vitamin C drink; small snack if your stomach is sensitive.
Coffee, tea, dairy, calcium, magnesium, zinc, high-fiber supplements.
Keep iron at least 4 hours away.
Try EOD dosing, hydrate, add magnesium at night (away from iron), or switch to bisglycinate.
Continue 3–6 months AFTER labs normalize — the storage tank refills last.
Choose based on tolerance, not price
| Form | Elemental iron | Notes |
|---|---|---|
| Ferrous sulfate 325 mg | ≈ 65 mg | Common, effective, cheap. Most likely to cause constipation. |
| Ferrous gluconate 324 mg | ≈ 38 mg | Gentler than sulfate; lower elemental dose per pill. |
| Ferrous fumarate 325 mg | ≈ 106 mg | Higher elemental iron; more GI symptoms possible. |
| Iron bisglycinate | Varies (often 25–36 mg) | Chelated — often better tolerated with fewer GI issues. |
| Heme iron polypeptide | Varies | Sourced from animal heme; gentle on the gut, pricier. |
| Liquid iron | Varies | Helpful if pills are hard to swallow; can stain teeth — use a straw. |
The "mg" on the front of the bottle is often the whole salt — not the elemental iron. Look for "elemental iron" on the Supplement Facts label.
Why less can be more
When you take iron, your gut releases a hormone called hepcidin that blocks absorption for the next ~24 hours. Taking iron every other day gives hepcidin time to fall, so a larger fraction of each dose is actually absorbed. It also cuts nausea and constipation.
- Mon: iron + vitamin C
- Tue: no iron
- Wed: iron + vitamin C
- Thu: no iron
- Fri: iron + vitamin C
- Sat/Sun: continue pattern
Oral iron isn't the only option
- •Ferritin very low with significant symptoms
- •Hemoglobin very low
- •Oral iron causes severe nausea or constipation
- •History of bariatric surgery
- •Celiac, IBD, or gut inflammation
- •Chronic PPI / acid-blocker use
- •Ongoing heavy bleeding losing iron faster than replacing
- •No improvement after 4–8 weeks of oral iron
IV iron infusions can replete stores in 1–2 visits. Ask your clinician if you check any two of these.