The Best Iron Supplement for Women
The best iron supplement for most women is Thorne Iron Bisglycinate, at $0.27 a day. One capsule gives 25 mg of iron to replace what periods take, in a form linked to fewer stomach complaints, and NSF, an independent lab, checks the bottle. If a blood test shows low iron, Nature Made Iron 65 mg is stronger and costs $0.04 a day.
Our pick for: Most women who take iron
- Per day
- $0.271 capsule: 25 mg iron
- A bottle
- $16.0060 capsules, 60 days, on Amazon
- Testing list
- NSF/ANSI 173Also NSF Certified for Sport
Why we pick it It is iron bisglycinate. In trials in pregnant women, this form caused fewer stomach complaints than other iron; trials in other women are few. NSF checks that the bottle holds what the label says, and screens it for drugs banned in sport. You take one capsule a day.
What you give up 25 mg is a daily dose, not a treatment dose. If a test shows you are low, a doctor may want more; see Nature Made 65 mg.
The best iron for your needs
Thorne suits most women. If a test shows you are low, or you want to spend less, pick one of these.
Low iron on a blood test: Nature Made Iron 65 mg
Nature Made Iron gives 65 mg in one tablet of ferrous sulfate. It is USP Verified and is also the main pick in our best iron supplement guide. 65 mg is above the 45 mg daily limit NIH sets for people who are not low, so take it only when a test shows you are low, and get retested.
Nature Made Iron 65 mg
$0.04 a day · $7.29 a bottle (180 tablets)
The same form for less: Solgar Gentle Iron
Solgar Gentle Iron is the iron our readers click on most. It is also iron bisglycinate, 25 mg in one vegan capsule, for less than half Thorne's price. It is not on a public testing list we check.
Solgar Gentle Iron
$0.11 a day · $9.65 a bottle (90 capsules)
How much iron women need, by stage of life
Daily needs from food and supplements together (NIH). Can't swallow pills? See the best iron gummies.
| Stage | Iron a day | What to take |
|---|---|---|
| Girls 14 to 18 | 15 mg | Food first. Ask a doctor before iron pills. |
| Women 19 to 50 with periods | 18 mg | Food first. Take Thorne if you eat little meat. |
| Heavy periods | Set by your doctor | See a doctor and ask for a ferritin test. If you are low: Nature Made 65 mg, then retest. |
| Pregnant | 27 mg | A prenatal vitamin with iron, plus extra only if your doctor says. |
| Breastfeeding | 9 mg | Often covered by food. If you lost a lot of blood giving birth, ask for a ferritin test. |
| Past menopause (51 and over) | 8 mg | Skip iron unless a test shows you are low; then find out why with a doctor. |
7 iron supplements compared
Cheapest per day first, at Amazon prices checked November 6, 2026. Amazon prices change, so the order can too.
| Iron | Cost per day | Why it is or is not the pick |
|---|---|---|
| Nature Made Iron 65 mg65 mg in 1 tablet · USP Verified | $0.04 | Our pick for low iron: strongest, costs least |
| NOW Iron 36 mg36 mg in 1 capsule · No testing list | $0.11 | Higher dose of the same form |
| Solgar Gentle Iron25 mg in 1 capsule · No testing list | $0.11 | Same form as Thorne, costs less |
| Klean Athlete Klean Iron27 mg in 1 tablet · NSF Certified for Sport + NSF/ANSI 173 | $0.21 | Tested like Thorne, costs less; a different form |
| Thorne Iron Bisglycinate25 mg in 1 capsule · NSF Certified for Sport + NSF/ANSI 173 | $0.27 | Our pick: bisglycinate, NSF-tested |
| Momentous Iron+25 mg in 1 capsule · NSF Certified for Sport + NSF/ANSI 173 | $0.33 | Same form as Thorne; vegan |
| OLLY Delightful Iron18 mg in 2 chewable tablets · NSF/ANSI 173 | $0.45 | Chewable; matches the 18 mg daily need |
Questions people ask
Will iron help if I am tired?
It can if your iron is low. In 198 women with fatigue, low ferritin and no anemia, 80 mg of iron a day for 12 weeks cut fatigue scores by 48%, against 29% on a placebo (Vaucher 2012). A ferritin test tells you whether you are low.
Should I take iron every day?
Not always. In women with low iron stores, a 60 mg dose taken every other day was absorbed better than the same dose taken daily (Stoffel 2017), and a later trial in 150 women found the same iron stores at the same total dose, with fewer stomach problems (von Siebenthal 2023). See when to take iron.
Is bisglycinate better than ferrous sulfate?
For your stomach, maybe. Bisglycinate caused fewer stomach complaints in trials in pregnant women (Fischer 2023). For raising iron, a 2024 guide for doctors says no form works better than another, and prefers ferrous sulfate because it costs least (AGA 2024). See ferrous sulfate vs bisglycinate.
Who should not take iron?
People with hemochromatosis, who already absorb too much iron (NIH). If you take thyroid medicine (levothyroxine), take iron at a different time, because iron makes it work less well (NIH). Keep iron away from children: an overdose is a leading cause of fatal poisoning in children under 6 (NIH).
How we picked
We started from the iron supplements we score and kept the ones women ask about most. We checked each against NSF/ANSI 173, USP Verified, NSF Certified for Sport, Informed Choice and Informed Sport. Thorne and Nature Made are also the gentler and main picks in our best iron supplement guide; here Thorne leads because a 25 mg daily dose suits topping up, and a blood test decides when you need the 65 mg tablet. Or see the iron guide.
Sources
- NIH Office of Dietary Supplements. Iron fact sheet for health professionals (daily needs by age, pregnancy and breastfeeding; upper limit; hemochromatosis; levothyroxine).
- DeLoughery TG, et al. AGA Clinical Practice Update on Management of Iron Deficiency Anemia: Expert Review. Clin Gastroenterol Hepatol. 2024.
- Vaucher P, et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012.
- Stoffel NU, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women. Lancet Haematol. 2017.
- von Siebenthal HK, et al. Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. EClinicalMedicine. 2023.
- Fischer JAJ, et al. The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev. 2023.
- Testing lists: NSF/ANSI 173 and NSF Certified for Sport (nsf.org), USP Verified (quality-supplements.org), Informed Choice and Informed Sport; our copies are dated on third-party tested iron.