Best Time to Take Iron Supplements for Maximum Absorption, According to Experts

Table of ContentsView AllTable of ContentsTimingAbsorptionOn an Empty StomachMorning vs. EveningAlternate DaysSide EffectsOther Tips

Table of ContentsView All

View All

Table of Contents

Timing

Absorption

On an Empty Stomach

Morning vs. Evening

Alternate Days

Side Effects

Other Tips

Iron is an essential mineral that your body needs for several functions. While iron is readily available in certain foods, some people need to take a supplement due to aniron deficiencyor other conditions. If you take an iron supplement, you may wonder if you are taking it correctly.

Iron supplementsshould generally be taken at least 30 minutes before a meal or two hours after a meal. However, some people may need to take iron with a small meal or snack to prevent upset stomach and other side effects.Iron pills must be taken at the right time of day and with the right food to maximize absorption and reap the benefits of this vital nutrient.

Why Timing Matters

Timing is one of the most important factors when taking an iron supplement.

If you take an iron supplement at the wrong time, your body may not absorb enough of the mineral. Foods, medications, other supplements, and certain health conditions can affect iron absorption.

In addition, taking iron properly may also reduce your risk of side effects like an upset stomach.

Because iron can interact with different substances, it’s typically best to take it alone, without food, medications, or other supplements. Some research shows that the best time to take iron is in the morning without food, coffee, or anything else.However, other studies have found that iron may also be well-absorbed in the evening.

Most importantly, iron should be taken safely and at the right dose.

Factors That Affect Absorption

Factors like supplement type, the foods you eat, and the medications you take may affect how well your body absorbs iron.

1. Supplement Type

There are multiple types of iron supplements, and some may be absorbed better than others.

Most iron supplements are made from ferric orferrousiron salts. Common types include ferrous sulfate, ferrousgluconate, ferriccitrate, and ferric sulfate.

Research shows that ferrous iron is absorbed better than ferric iron. This may be because ferric iron must undergo a longer digestion and absorption process than ferrous iron.

The nutrition facts panel on the supplement label will include the type of iron. In addition to ferrous sulfate and ferrous gluconate, other ferrous iron forms in a supplement include ferrousfumarateand ferrousbisglycinate.

2. The Foods You Take Iron With

It’s best to take iron supplements on an empty stomach. However, if you need to take iron with food, it’s good to know which foods may affect absorption.

Dairy products and other calcium-rich foods should not be taken with iron.Calciumhas been found to reduce the absorption of iron. This may be because calcium and iron use similar processes when absorbed in the intestine.

Phytatesandpolyphenols—compounds typically found in plant-based foods like whole grains, vegetables, and coffee—may also block iron absorption.Therefore, it’s recommended that you avoid taking iron supplements with plant-based foods.

It’s worth noting that some foods, such as those containingvitamin C, enhance iron absorption when consumed together. Consuming animal protein along with iron may also enhance the mineral’s absorption.

3. Other Supplements

Other dietary supplements taken at the same time as iron may alter the effectiveness of your iron supplement.

Iron pills should not be taken at the same time as supplements that contain calcium or phosphorus.Antacidsare a common calcium-containing supplement.

Calcium and iron compete for uptake in the intestine, potentially reducing iron absorption.Similarly, phosphorus binds to iron during digestion, lowering its absorption.

To avoid these interactions, it is recommended that you take iron at least two hours apart from supplements that contain calcium or phosphorus.

4. Medication Interactions

Iron may interact with certain medications. These interactions may decrease how much iron your body absorbs.

There is evidence that iron may interact with:

Iron may also interact with certain antibiotics, includingpenicillin,tetracycline, andciprofloxacin.

These medications should be taken at least two hours apart from iron to avoid interactions.

Talk with a healthcare provider about safely taking iron supplements while using these or other medications.

5. Your Stomach pH

Iron needs to be absorbed in an acidic environment.

Your stomach is naturally acidic, allowing iron to be properly digested and absorbed. However, certain medications and other factors may cause the stomach to become less acidic. If the pH of your stomach becomes too high, your body may not be able to absorb iron properly.

Proton pump inhibitors (Prevacid, Prilosec, etc.) are one type of medication that increases the pH of your stomach, causing it to become less acidic. Therefore, avoiding taking iron simultaneously as a PPI is essential to avoid poor iron absorption.

6. Specific Health Conditions

People with specific health conditions may struggle to absorb enough iron from food or supplements.

These health conditions include:

Certain surgeries, such as intestinal resections, may also lead to poor iron absorption.

Fortunately, iron supplements and other treatments may help people with these and other conditions get enough iron.

Should You Take Iron on an Empty Stomach?

Iron supplements may work best when taken on an empty stomach.

Various studies have found that iron is best absorbed when taken without food. Taking iron without food may lower the chance of interactions leading to poor iron absorption.

However, some people may need to take iron with small amounts of food to avoid side effects like nausea ordiarrhea.

In one study on women withiron deficiency anemia, participants who took ferrous iron supplements in the morning absorbed the mineral better than those who took a supplement in the afternoon. The study also showed that taking iron on an empty stomach and with an ascorbic acid (vitamin C) supplement improved absorption.

However, other studies have found no difference in absorption between taking iron in the morning or the evening.

For some people, the evening may be the most convenient time to take an iron supplement. Overall, it’s important to remember to take one if it has been recommended.

What About Alternate Day Supplementation?

Some studies suggest that taking iron every other day may be more effective than taking it daily.

According to one study, alternate-day iron supplementation may take longer to correct iron deficiency anemia, but it may also lead to fewer gastrointestinal (stomach) side effects. This may appeal to some people, especially if iron supplements cause uncomfortable side effects. However, alternate-day supplementation may not be suitable for those with severe iron deficiency anemia.

Research is still emerging in this area, so talk with a healthcare provider to determine whether alternate-day supplementation is right for you.

Potential Side Effects

Some people may experience side effects when taking iron supplements.

Possible iron supplement side effects include:

If you take too much iron, you may experience additional side effects. These include stomach pain, ulcers, inflammation of the stomach, andzinc deficiency.

To lower the risk of side effects, use iron supplements only as directed and never take more than you should.

Other Tips for Taking Iron Supplements

There are some factors to consider before you start taking iron supplements.

Summary

Iron is an essential mineral that many people need to obtain from supplements due to various health conditions.

Many factors can affect iron absorption, including supplement type, foods eaten, medications taken, and stomach pH.

Research shows that iron may be best absorbed in the morning and on an empty stomach. Iron supplements may also be absorbed better when taken every other day.

However, you can still benefit from iron supplements no matter when you take them. Just be sure to follow dosing directions and talk with a healthcare provider as needed.

13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Taking iron supplements.National Institutes of Health.Iron - fact sheet for health professionals.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. doi:10.1002/ajh.26987Attwell C, McKay A, Sim M, et al.Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers.Eur J Sport Sci. 2023;23(12):2275-2282. doi:10.1080/17461391.2023.2224285Piskin E, Cianciosi D, Gulec S, Tomas M, Capanoglu E.Iron absorption: factors, limitations, and improvement methods.ACS Omega. 2022;7(24):20441-20456. doi:10.1021/acsomega.2c01833Stoffel NU, von Siebenthal HK, Moretti D, Zimmermann MB.Oral iron supplementation in iron-deficient women: How much and how often?.Mol Aspects Med. 2020;75:100865. doi:10.1016/j.mam.2020.100865Abioye AI, Okuneye TA, Odesanya AO, et al.Calcium intake and iron status in human studies: a systematic review and dose-response meta-analysis of randomized trials and crossover studies.J Nutr. 2021;151(5):1084-1101. doi:10.1093/jn/nxaa437Nakanishi T, Hasuike Y, Nanami M, Yahiro M, Kuragano T.Novel iron-containing phosphate binders and anemia treatment in CKD: oral iron intake revisited.Nephrol Dial Transplant. 2016;31(10):1588-1594. doi:10.1093/ndt/gfv268Moris W, Verhaegh PLM, Verbeek J, et al.Absorption of nonheme iron during gastric acid suppression in patients with hereditary hemochromatosis and healthy controls.Am J Physiol Gastrointest Liver Physiol. 2021;320(6):G1105-G1110. doi:10.1152/ajpgi.00371.2020Saboor M, Zehra A, Qamar K, Moinuddin.Disorders associated with malabsorption of iron: A critical review.Pak J Med Sci. 2015;31(6):1549-1553. doi:10.12669/pjms.316.8125Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB.Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women.Haematologica. 2020;105(5):1232-1239. doi:10.3324/haematol.2019.220830von 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. doi:10.1016/j.eclinm.2023.102286National Institutes of Health.Iron - fact sheet for consumers.

13 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Taking iron supplements.National Institutes of Health.Iron - fact sheet for health professionals.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. doi:10.1002/ajh.26987Attwell C, McKay A, Sim M, et al.Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers.Eur J Sport Sci. 2023;23(12):2275-2282. doi:10.1080/17461391.2023.2224285Piskin E, Cianciosi D, Gulec S, Tomas M, Capanoglu E.Iron absorption: factors, limitations, and improvement methods.ACS Omega. 2022;7(24):20441-20456. doi:10.1021/acsomega.2c01833Stoffel NU, von Siebenthal HK, Moretti D, Zimmermann MB.Oral iron supplementation in iron-deficient women: How much and how often?.Mol Aspects Med. 2020;75:100865. doi:10.1016/j.mam.2020.100865Abioye AI, Okuneye TA, Odesanya AO, et al.Calcium intake and iron status in human studies: a systematic review and dose-response meta-analysis of randomized trials and crossover studies.J Nutr. 2021;151(5):1084-1101. doi:10.1093/jn/nxaa437Nakanishi T, Hasuike Y, Nanami M, Yahiro M, Kuragano T.Novel iron-containing phosphate binders and anemia treatment in CKD: oral iron intake revisited.Nephrol Dial Transplant. 2016;31(10):1588-1594. doi:10.1093/ndt/gfv268Moris W, Verhaegh PLM, Verbeek J, et al.Absorption of nonheme iron during gastric acid suppression in patients with hereditary hemochromatosis and healthy controls.Am J Physiol Gastrointest Liver Physiol. 2021;320(6):G1105-G1110. doi:10.1152/ajpgi.00371.2020Saboor M, Zehra A, Qamar K, Moinuddin.Disorders associated with malabsorption of iron: A critical review.Pak J Med Sci. 2015;31(6):1549-1553. doi:10.12669/pjms.316.8125Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB.Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women.Haematologica. 2020;105(5):1232-1239. doi:10.3324/haematol.2019.220830von 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. doi:10.1016/j.eclinm.2023.102286National Institutes of Health.Iron - fact sheet for consumers.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

MedlinePlus.Taking iron supplements.National Institutes of Health.Iron - fact sheet for health professionals.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. doi:10.1002/ajh.26987Attwell C, McKay A, Sim M, et al.Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers.Eur J Sport Sci. 2023;23(12):2275-2282. doi:10.1080/17461391.2023.2224285Piskin E, Cianciosi D, Gulec S, Tomas M, Capanoglu E.Iron absorption: factors, limitations, and improvement methods.ACS Omega. 2022;7(24):20441-20456. doi:10.1021/acsomega.2c01833Stoffel NU, von Siebenthal HK, Moretti D, Zimmermann MB.Oral iron supplementation in iron-deficient women: How much and how often?.Mol Aspects Med. 2020;75:100865. doi:10.1016/j.mam.2020.100865Abioye AI, Okuneye TA, Odesanya AO, et al.Calcium intake and iron status in human studies: a systematic review and dose-response meta-analysis of randomized trials and crossover studies.J Nutr. 2021;151(5):1084-1101. doi:10.1093/jn/nxaa437Nakanishi T, Hasuike Y, Nanami M, Yahiro M, Kuragano T.Novel iron-containing phosphate binders and anemia treatment in CKD: oral iron intake revisited.Nephrol Dial Transplant. 2016;31(10):1588-1594. doi:10.1093/ndt/gfv268Moris W, Verhaegh PLM, Verbeek J, et al.Absorption of nonheme iron during gastric acid suppression in patients with hereditary hemochromatosis and healthy controls.Am J Physiol Gastrointest Liver Physiol. 2021;320(6):G1105-G1110. doi:10.1152/ajpgi.00371.2020Saboor M, Zehra A, Qamar K, Moinuddin.Disorders associated with malabsorption of iron: A critical review.Pak J Med Sci. 2015;31(6):1549-1553. doi:10.12669/pjms.316.8125Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB.Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women.Haematologica. 2020;105(5):1232-1239. doi:10.3324/haematol.2019.220830von 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. doi:10.1016/j.eclinm.2023.102286National Institutes of Health.Iron - fact sheet for consumers.

MedlinePlus.Taking iron supplements.

National Institutes of Health.Iron - fact sheet for health professionals.

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. doi:10.1002/ajh.26987

Attwell C, McKay A, Sim M, et al.Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers.Eur J Sport Sci. 2023;23(12):2275-2282. doi:10.1080/17461391.2023.2224285

Piskin E, Cianciosi D, Gulec S, Tomas M, Capanoglu E.Iron absorption: factors, limitations, and improvement methods.ACS Omega. 2022;7(24):20441-20456. doi:10.1021/acsomega.2c01833

Stoffel NU, von Siebenthal HK, Moretti D, Zimmermann MB.Oral iron supplementation in iron-deficient women: How much and how often?.Mol Aspects Med. 2020;75:100865. doi:10.1016/j.mam.2020.100865

Abioye AI, Okuneye TA, Odesanya AO, et al.Calcium intake and iron status in human studies: a systematic review and dose-response meta-analysis of randomized trials and crossover studies.J Nutr. 2021;151(5):1084-1101. doi:10.1093/jn/nxaa437

Nakanishi T, Hasuike Y, Nanami M, Yahiro M, Kuragano T.Novel iron-containing phosphate binders and anemia treatment in CKD: oral iron intake revisited.Nephrol Dial Transplant. 2016;31(10):1588-1594. doi:10.1093/ndt/gfv268

Moris W, Verhaegh PLM, Verbeek J, et al.Absorption of nonheme iron during gastric acid suppression in patients with hereditary hemochromatosis and healthy controls.Am J Physiol Gastrointest Liver Physiol. 2021;320(6):G1105-G1110. doi:10.1152/ajpgi.00371.2020

Saboor M, Zehra A, Qamar K, Moinuddin.Disorders associated with malabsorption of iron: A critical review.Pak J Med Sci. 2015;31(6):1549-1553. doi:10.12669/pjms.316.8125

Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB.Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women.Haematologica. 2020;105(5):1232-1239. doi:10.3324/haematol.2019.220830

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. doi:10.1016/j.eclinm.2023.102286

National Institutes of Health.Iron - fact sheet for consumers.

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