How much iron should I take for low ferritin or anemia?

Typical treatment for iron deficiency uses roughly 60-120mg of elemental iron, but newer evidence supports giving it as a single dose every other day rather than multiple times daily, because that absorbs a higher fraction and is gentler on the gut. Many clinicians now use about 60-100mg of elemental iron on alternate days. The right dose depends on how low you are and should be guided by your doctor and follow-up bloodwork — this is treatment, not casual supplementation.

How long does it take to raise ferritin?

Longer than most people expect. Hemoglobin (anemia) often improves within a few weeks, but rebuilding your ferritin — the iron storage tank — typically takes about 3-6 months of consistent supplementation, and sometimes longer. That is why you should keep taking iron, as directed, well past the point of feeling better, and recheck ferritin (not just hemoglobin) before stopping. Quitting as soon as you feel fine usually leaves stores unfilled and the deficiency returns.

What is the best iron to take for anemia?

Any well-absorbed iron salt treats anemia; the practical difference is tolerability, because you will be taking it for months. Ferrous bisglycinate ("gentle iron") is well-absorbed and far less likely to cause constipation and nausea than ferrous sulfate, which improves the odds you actually stay on it long enough to refill stores. Pair it with vitamin C and take it away from calcium, coffee, and tea.

What causes low iron, and when is it serious?

In menstruating women and pregnancy, blood loss and increased demand are the usual causes. But iron deficiency in a man or a postmenopausal woman is a red flag that requires investigation, because it often signals gastrointestinal bleeding — including from ulcers or, occasionally, colon cancer. So the cause matters as much as the treatment: do not just supplement and move on. Iron deficiency without an obvious reason warrants a doctor identifying the source.

Iron for Anemia & Low Ferritin (2026): How Much, How Long, How to Absorb It

By Verified Supplement Data · Updated May 31, 2026 · Methodology · About Us

Treating low iron is a months-long project, not a quick fix. Use a well-tolerated iron (bisglycinate), commonly ~60-100mg elemental, increasingly given every other day (absorbs better, gentler — Stoffel 2017, PMID: 29032957), with vitamin C.

Hemoglobin recovers in weeks; ferritin (your iron tank) takes 3-6 months. Keep going past feeling better, and retest ferritin before stopping.

And find the cause — unexplained iron deficiency in men or postmenopausal women can signal GI bleeding and needs a doctor. Solgar Gentle Iron is our value pick.

The dose — and why alternate-day is the modern approach

Standard treatment historically meant 150-200mg of elemental iron a day in divided doses — effective, but rough on the gut, and partly self-defeating. We now understand that a large iron dose spikes hepcidin, the hormone that shuts down iron absorption for roughly a day, so dosing more often doesn't proportionally help. Research showed a single dose every other day raised the absorbed fraction and cut side effects (Stoffel 2017, PMID: 29032957; Kamath 2024, PMID: 37979057). The AGA's clinical update on iron deficiency reflects this shift toward lower-frequency dosing (DeLoughery 2024, PMID: 38864796). Practically: many people do well on ~60-100mg elemental iron every other day, with vitamin C — but let your doctor set the target based on how depleted you are.

How long: the ferritin patience problem

This is where most people undershoot. There are two finish lines, and the obvious one comes first. Your hemoglobin (the anemia itself) often rebounds within a few weeks — you feel better, energy returns, and it's tempting to stop. But your ferritin, the storage tank that has to be refilled to prevent relapse, lags far behind and usually needs 3-6 months (sometimes more) of consistent iron. Stop at "I feel fine" and you typically slide right back into deficiency. The rule: keep taking iron as directed well past symptom relief, and recheck ferritin — not just hemoglobin — before you quit.

Don't skip the "why"

Iron deficiency is a symptom with a cause, and the cause sometimes matters more than the iron. In menstruating women and pregnancy, the reason is usually obvious (blood loss, higher demand). But low iron in a man or a postmenopausal woman is a genuine red flag — it commonly points to gastrointestinal bleeding, from something benign like an ulcer to, occasionally, colon cancer. Supplementing iron without finding the source can mask a problem that needs treatment. If your deficiency has no obvious explanation, the supplement is secondary to getting it investigated.

Iron for treating deficiency, ranked

Iron supplements ranked by cost per day
Product	Form	Elemental Iron	Servings	Price	Cost/Day	Certification	Buy
NOW Foods Iron 36 mg Double Strength (Ferrochel) Budget Pick	Ferrous bisglycinate	36mg	90	$9.27	$0.10	None	Buy
Solgar Gentle Iron (Iron Bisglycinate) 25 mg Best Value	Ferrous bisglycinate	25mg	90	$9.65	$0.11	None	Buy
Thorne Iron Bisglycinate 25 mg Quality Pick	Ferrous bisglycinate	25mg	60	$16.00	$0.27	NSF Certified for Sport	Buy
MegaFood Blood Builder	Whole-food + cofactors	26mg	90	$28.99	$0.32	NSF Certified	Buy

Bisglycinate matters more here than usual: you'll be on iron for months, so tolerability determines whether you actually finish the job. Pair with vitamin C; keep away from calcium, coffee, and tea.

Frequently asked questions

How much iron for low ferritin/anemia?

Commonly ~60-100mg elemental, increasingly given every other day (absorbs better, gentler). The exact dose depends on how low you are — let your doctor and follow-up bloodwork guide it.

How long to raise ferritin?

Hemoglobin improves in weeks, but refilling ferritin takes ~3-6 months. Keep going past feeling better and recheck ferritin (not just hemoglobin) before stopping.

Best iron for anemia?

Any well-absorbed salt treats it; bisglycinate is far better tolerated than ferrous sulfate, so you're more likely to stay on it long enough. Pair with vitamin C, away from calcium/coffee/tea.

When is low iron serious?

Unexplained deficiency in a man or postmenopausal woman is a red flag for GI bleeding (ulcer, sometimes colon cancer) and needs investigation — don't just supplement and move on.

Related guides

Best Iron Supplement
Iron for Women
Ferrous Sulfate vs Bisglycinate
B12 & Fatigue — another deficiency to rule out
Vitamin C — take alongside iron for absorption

Sources

Stoffel NU, et al. "Iron absorption from oral iron supplements given on consecutive versus alternate days." Lancet Haematol. 2017;4(11):e524-e533. PMID: 29032957
DeLoughery TG, et al. "AGA Clinical Practice Update on Management of Iron Deficiency Anemia: Expert Review." Clin Gastroenterol Hepatol. 2024. PMID: 38864796
Kamath S, et al. "Daily versus alternate day oral iron therapy in iron deficiency anemia: a systematic review." Naunyn Schmiedebergs Arch Pharmacol. 2024. PMID: 37979057