Last checked November 2026 against 10 sources · Editorial policy
Iron supplements for heavy periods in perimenopause
Heavy periods are one of the most common causes of low iron, and they often get heavier in perimenopause. First test ferritin: under 30 ng/mL usually means iron deficiency. The standard treatment is ferrous sulfate 325 mg a day or every other day; alternate-day dosing is absorbed better and causes fewer stomach problems. Expect about 6 months of tablets, and treat the bleeding too.
Heavy periods in perimenopause drain iron. Which iron to take, why every other day absorbs better, how long to take it, side effects and when to test ferritin.
Iron for heavy periods: expectation vs reality
What people often expect
“If I'm tired and my periods are heavy, I can take a daily iron pill, maybe two, and feel better in a few weeks”
What the evidence shows
Taking iron twice a day or every day raises hepcidin, a hormone that blocks iron absorption the next day. Trials in iron-depleted women found that every-other-day doses were absorbed better and caused fewer stomach side effects. Iron stores take months to refill: the NHS says to expect about 6 months of tablets, and the bleeding itself needs treating.
Iron supplements for heavy periods: what works
Why heavy periods drain iron
Every period removes iron with the blood, and heavy bleeding can take out more than food puts back. A 2023 review by Malcolm Munro and colleagues in the American Journal of Obstetrics and Gynecology called heavy menstrual bleeding a major contributor to iron deficiency and iron deficiency anemia, often normalized by women and doctors alike. In perimenopause, cycles can become heavier and longer, so the drain can grow just as tiredness gets blamed on hormones.
Learn more →Symptoms of low iron
Iron deficiency anaemia causes tiredness and lack of energy, shortness of breath, noticeable heartbeats, paler skin and sometimes hair loss, according to the NHS. A 2025 JAMA review adds irritability, low mood, poor concentration and restless legs. Many of these overlap with perimenopause symptoms, which is why a blood test matters more than guessing from how you feel. Low iron and perimenopause can also happen at the same time. You're not imagining it. And you can't tell low iron from hormones by feel alone.
Learn more →Test ferritin before you take iron
Ferritin measures stored iron. The JAMA review says iron deficiency is usually diagnosed by ferritin under 30 ng/mL in people without inflammation, or by transferrin saturation under 20%. Ferritin can be low before hemoglobin drops, so a normal blood count doesn't rule it out. Ask for a full blood count and ferritin together, from your doctor or a direct-to-consumer lab. We'd push for the number. A normal hemoglobin isn't the same thing.
Which iron supplement to take
The 2025 JAMA review by Michael Auerbach, Thomas DeLoughery and Jennifer Tirnauer names ferrous sulfate 325 mg a day or on alternate days as typical first-line treatment; it's cheap and well studied. Gentler forms such as iron bisglycinate are sold for fewer stomach problems, but the strongest evidence on dosing comes from ferrous sulfate trials. The amount that counts is elemental iron, which is printed on the Supplement Facts label. Check yours. Many labels list both numbers.
Why every other day works better
In a trial by Nicole Stoffel and Michael Zimmermann's group at ETH Zurich of iron-depleted women given 60 mg of iron, cumulative absorption was 21.8% on alternate days against 16.3% on consecutive days. Splitting a dose into two a day didn't raise absorption. A 2023 trial of 150 women found that at the same total dose, alternate-day iron gave similar ferritin, less iron deficiency at 6 months and fewer stomach side effects. This surprised us: less often worked better.
How to take iron for better absorption
Take iron in the morning on its own. The NHS says orange juice after a tablet may help absorption, while tea, coffee and milk can reduce it. MedlinePlus says black tea binds dietary iron, and certain antibiotics such as doxycycline should be taken 2 hours before or after iron. If tablets upset your stomach, the NHS suggests taking them with or just after food. Coffee with breakfast? Take the iron an hour later.
Side effects of iron supplements
Common side effects are constipation or diarrhoea, feeling sick, stomach pain and darker poo, which is expected. The NHS advises keeping going even with side effects and talking to a doctor if they're hard to bear. Alternate-day dosing cut stomach side effects in the 2023 trial. Keep iron away from children: an overdose can be fatal for a young child. We know it's unpleasant. Don't quit after a week.
How much iron women need after 50
The recommended daily intake for women is 18 mg from age 19 to 50 and 8 mg from 51 on, according to MedlinePlus, because periods stop. Treatment doses for deficiency are far higher than these daily needs. Once periods end and stores are refilled, most women don't need an iron supplement, and long-term high-dose iron without a reason isn't advised. We'd stop once ferritin is back up and your periods are over.
Iron supplements and heavy bleeding: treat both
Iron replaces what was lost, but if bleeding stays heavy the deficit comes back. The 2023 review stresses that heavy menstrual bleeding and iron deficiency should be managed together. The NHS says heavy periods can be treated with medicine, and a doctor should look for causes such as fibroids or polyps. Taking iron while ignoring the bleeding is like refilling a leaking tank. If nobody has asked why you're bleeding so much, ask. You're allowed to.
Learn more →Iron deficiency by the numbers
From the studies on this page
of non-pregnant women of reproductive age in high-income countries have iron deficiency without anemia
38%
have iron deficiency anemia
13%
30 ng/mL
6 months
Figures from a 2025 JAMA review of iron deficiency in adults.
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Iron supplements and tests compared
Ferritin blood test
Good for
Shows whether iron stores are low before you start; under 30 ng/mL usually means deficiency.Watch
Inflammation can push ferritin up and hide low iron; ask about transferrin saturation too.Our pick: HealthLabs ferritin blood test. Order online, no doctor's referral; visit a nearby lab. Not available in NY, NJ, MD, RI, ND or HI.
Check price at HealthLabs →Ferrous sulfate 325 mg
Good for
Typical first-line oral iron; cheap; the form used in most dosing trials.Watch
Stomach side effects are common; every other day is gentler.Alternate-day iron schedule
Good for
Better absorption and fewer stomach side effects at the same total dose.Watch
Takes discipline; use a phone reminder.Intravenous iron
Good for
Refills stores quickly when tablets fail, aren't tolerated or blood loss is heavy.Watch
Needs a clinic visit and a doctor's referral.Treating the heavy bleeding
Learn more →Good for
Stops the drain, so iron levels can recover and stay up.Watch
Needs a doctor's assessment of the cause.
Before you start an iron supplement
- Get ferritin and a blood count first; taking iron you don't need can cause harm and hides the real cause of tiredness.
- Read elemental iron in mg on the label, not just the salt name. Ferrous sulfate 325 mg isn't 325 mg of iron.
- Take it every other day, in the morning, with orange juice rather than tea or coffee.
- Separate iron from antibiotics such as doxycycline by 2 hours.
- Store it out of children's reach; iron overdose can be fatal for a young child.
When low iron needs a doctor
Urgent: Soaking a pad or tampon every hour, or passing large clots
See a doctor; very heavy bleeding needs its own assessment, not just iron.
More →Urgent: Shortness of breath, chest pain or a racing heart
Get urgent care; severe anaemia can strain the heart.
Low iron with no heavy periods, or after menopause
A doctor should look for bleeding in the gut or poor absorption, such as celiac disease.
More →Ferritin not rising after 2 to 3 months of tablets
Ask about intravenous iron and why absorption may be poor.
Iron supplements in perimenopause: questions women ask
What is the best iron supplement for heavy periods?
Ferrous sulfate 325 mg is the standard first choice in the 2025 JAMA review, taken daily or every other day. Trials found alternate-day dosing absorbed better and caused fewer stomach problems. If tablets don't work or you can't tolerate them, intravenous iron is the next step.
Can perimenopause cause iron deficiency?
Not by itself, but the heavier, longer periods many women get in perimenopause can. Heavy menstrual bleeding is one of the main causes of iron deficiency in women of all ages, from the first period to menopause. If you're soaking through pads, you're probably losing more than you think.
How long does it take for iron supplements to work?
Energy may improve within weeks as hemoglobin rises, but refilling stores takes longer. The NHS says to expect about 6 months of tablets, with repeat blood tests to check progress. Keep going after you feel better, until ferritin is back in range. You'll likely feel it before the lab numbers catch up.
Should I take iron every day or every other day?
Every other day, for most women. In the Swiss trials, iron taken every other day was absorbed better because a daily dose raises hepcidin, which blocks the next dose. A 2023 trial of 150 women found fewer stomach side effects and less iron deficiency at 6 months with alternate days.
What ferritin level is too low?
Under 30 ng/mL usually means iron deficiency in people without inflammation, according to the JAMA review. Some labs flag only much lower values, so ask for the number, not just whether it's normal. Retest after about 3 months of treatment to see if it's rising. We'd write it down each time.
What foods are high in iron?
Lean meat, fish and poultry contain the best-absorbed iron. Beans and dark leafy greens add more, and eating them with some meat or vitamin C foods can raise absorption up to three times. Black tea binds iron, so drink it between meals. Food alone rarely fixes a true deficiency from heavy bleeding.
Can I stop iron after menopause?
Usually, once periods have stopped and your stores are refilled. Women's daily need drops from 18 mg to 8 mg after 50. If you're still low after menopause, a doctor should look for another source of blood loss. You'll want one last ferritin check before you stop.
Sources
- Auerbach M, DeLoughery TG, Tirnauer JS. Iron Deficiency in Adults: A Review. JAMA. 2025;333(20):1813-1823.
- Munro MG, Mast AE, Powers JM, et al. The relationship between heavy menstrual bleeding, iron deficiency, and iron deficiency anemia. Am J Obstet Gynecol. 2023;229(1):1-9.
- 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.
- 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.
- NHS. Iron deficiency anaemia: symptoms, causes and treatment. Accessed November 12, 2026.
- NHS. Heavy periods.
- HealthLabs. Ferritin blood test page (checked October 2026).
- Stoffel NU, Zeder C, Brittenham GM, et al. 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.
- MedlinePlus (U.S. National Library of Medicine). Iron in diet: food sources and recommended intake. Accessed November 12, 2026.
- MedlinePlus (U.S. National Library of Medicine). Ferrous sulfate: drug information, interactions and side effects. Accessed November 12, 2026.
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