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Ingredient guide

Best time to take an iron supplement: morning or night?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

In a study of women with low iron, iron taken in the morning away from meals, with vitamin C, was absorbed best; coffee cut absorption by 54%, and an afternoon dose tended to be absorbed less. If iron upsets your stomach, taking it with food is a reasonable trade.1,2

Key facts

  • Splitting a day's iron into two doses raised hepcidin without adding to the iron absorbed.3
  • Calcium is the one common food component that might reduce the absorption of both heme and nonheme iron.2
  • Medicines that lower stomach acid can reduce how much nonheme iron is absorbed.2
  • After a dose of 60 mg or more, iron taken the next day was absorbed 35% to 45% less.4

Morning or later in the day

In a study of 34 women with low iron stores, a 100 mg dose taken in the afternoon was absorbed 37% less than the same dose taken in the morning, a difference that just missed statistical significance.1

The pattern fits what is known about hepcidin, the hormone that limits iron absorption: in the same study it was higher in the afternoon than in the morning. None of the studies read for this page tested bedtime doses, so the evidence favors the morning without ruling out other times.1

What to take it with, and what to avoid

In the same study, taking the dose with 80 mg of vitamin C raised absorption by 30%, and 500 mg of vitamin C added nothing more.1

Coffee taken with the dose cut absorption by 54%, and a breakfast with coffee and orange juice cut it by 66%.1

Vitamin C, meat, poultry and seafood help the body absorb nonheme iron, while phytate in grains and beans and some polyphenols reduce it. In a varied Western diet these effects are small for most people.2,5

In practice that means swallowing iron with water or a glass of orange juice and leaving coffee and a full breakfast until later. In the study, iron taken with orange juice alone was absorbed about four times better than iron taken with coffee or breakfast.1

Empty stomach or with food

High doses of iron taken on an empty stomach are the most likely to upset it, and taking iron with food can lessen these effects.2,5

So there is a trade. Away from meals gives the most absorption, while food makes side effects less likely. If an empty stomach makes you give up on iron altogether, the better absorption is wasted, and taking it with a light meal is the more useful choice.1,2

Every day or every other day

In women with low iron stores, 60 mg taken on alternate days was absorbed better than the same dose taken on consecutive days: 21.8% against 16.3% of the iron given, or 175 mg against 131 mg absorbed in total.3

A later trial compared the two schedules over 6 months in 150 young women, at the same total dose. Ferritin finished at the same level; the alternate-day group had fewer stomach complaints and fewer women still low at the end, while the daily group got there in half the time.6

Keep calcium apart

Calcium might reduce iron absorption, although this has not been firmly established, so experts suggest taking calcium and iron supplements at different times of day.2,5

If you take both, a simple pattern is iron in the morning and calcium later with a meal, which also suits calcium carbonate, a form absorbed best with food.2,7

Medicines that need spacing

Iron has to be timed around levothyroxine, levodopa, tetracycline and quinolone antibiotics and dolutegravir, because it can bind them in the gut and lower their absorption. Medicines that lower stomach acid reduce iron absorption instead. The labels set different rules for each medicine, so ask your pharmacist to build one schedule that fits them all.5,8,9,10

Questions people ask

Should I take iron at night?

The studies read for this page favor the morning, when hepcidin, the hormone that limits absorption, was lower than in the afternoon. None of them tested bedtime doses.1

Can I take iron with milk?

It is better not to. Milk is rich in calcium, and calcium might reduce iron absorption, so keep milk and other calcium-rich foods for another time of day.2,11

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Sources

  1. von Siebenthal HK, Moretti D, Zimmermann MB, Stoffel NU. Effect of dietary factors and time of day on iron absorption from oral iron supplements in iron deficient women. Am J Hematol. 2023;98(9):1356-1363. Opened 2026-10-07.
  2. Office of Dietary Supplements, National Institutes of Health. Iron: Fact Sheet for Health Professionals. Updated September 4, 2025. Opened 2026-10-07.
  3. Stoffel NU, Cercamondi CI, Brittenham G, 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: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524-e533. Opened 2026-10-07.
  4. Moretti D, Goede JS, Zeder C, et al. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015;126(17):1981-1989. Opened 2026-10-07.
  5. Office of Dietary Supplements, National Institutes of Health. Iron: Fact Sheet for Consumers. Updated August 17, 2023. Opened 2026-10-07.
  6. von Siebenthal HK, Gessler S, Vallelian F, et al. Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. EClinicalMedicine. 2023;65:102286. Opened 2026-10-07.
  7. Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Consumers. Updated September 14, 2023. Opened 2026-10-07.
  8. Levothyroxine sodium tablets: prescribing information (Alvogen). DailyMed, U.S. National Library of Medicine. Effective September 15, 2026. Opened 2026-10-07.
  9. Ciprofloxacin tablets: prescribing information (Westminster Pharmaceuticals). DailyMed, U.S. National Library of Medicine. Effective September 25, 2026. Opened 2026-10-07.
  10. Dolutegravir tablets and tablets for oral suspension: prescribing information (ViiV Healthcare). DailyMed, U.S. National Library of Medicine. Effective August 25, 2026. Opened 2026-10-07.
  11. Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Health Professionals. Updated June 22, 2026. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.