"My periods have always been like this." This is the phrase that delays the most diagnoses. One in three women will experience heavy periods at some point in their lives, and most don't know it, because they only have their own periods as a reference. Yet, each milliliter of blood lost carries away 0.5 mg of iron, and the body only absorbs one or two per day. The balance never quite adds up.
This article helps you objectively assess the heaviness of your periods with concrete criteria, explains what a cycle costs in iron, reviews the causes, the tests to request, how to compensate each month, and especially when the issue requires a gynecologist. It's the "menstruating women" companion to our complete guide to iron deficiency.
14 mg of iron chelated to glycine (100% of NRV), 80 mg of vitamin C for absorption, and 200 µg of vitamin B9. One vegetarian capsule in the morning, with no metallic taste or constipation. Made in France.
Periods are considered heavy beyond 80 mL per cycle, which in practice translates to more than 7 days of bleeding, a protection changed every one or two hours for several hours, blood clots larger than 2 cm, or overflow. A normal cycle costs 15 to 30 mg of iron; heavy periods cost 40 to over 100 mg, which diet, absorbed at only 10 or 15%, does not compensate for. Result: one in five menstruating women has low ferritin, with fatigue, hair loss, and shortness of breath often attributed to something else. The approach: objectively assess a cycle, measure ferritin, CRP, and hemoglobin, identify the cause with your gynecologist (fibroids, adenomyosis, endometriosis, copper IUD, thyroid, coagulation, perimenopause), compensate each month with well-tolerated iron taken correctly, and treat the source. Bleeding between periods, after age 45, or with discomfort: consultation without delay.
1. What a menstrual cycle costs in iron
Blood contains approximately 0.5 mg of iron per milliliter, contained in hemoglobin. Each cycle is therefore a net loss of iron that the body, which cannot manufacture it, must recover from food. However, intestinal absorption is low: 15 to 35% for iron from meat, 2 to 20% for plant-based iron, 10 to 15% on average for a mixed diet. A normal cycle already requires 1 to 2 mg of absorbed iron per day in addition to baseline losses; heavy menstruation doubles or triples this need. This is why ANSES sets the reference at 16 mg per day for women with heavy menstrual losses, compared to 11 mg for others.
The arithmetic is relentless and slow. A deficit of 10 mg per cycle goes unnoticed for months, then ferritin, which reflects reserves, falls below 30 µg/L, then below 15, and one day hemoglobin drops: that's anemia. A landmark review reminds us that heavy menstruation, pregnancy, and postpartum are the three major causes of iron deficiency in women, and that this deficiency remains massively underdiagnosed and undertreated (Cappellini, Fertil Steril, 2022). Details of the stages are in the complete guide.
2. Heavy menstruation: objective criteria
| Criteria | Normal menstruation | Heavy menstruation |
|---|---|---|
| Duration | 3 to 7 days | More than 7 days, or more than 2 days of very heavy bleeding |
| Protection change | Every 3 to 4 hours at most during peak flow | Every hour or two hours for several hours in a row |
| Night | One pad lasts the night | Need to get up to change, or use double protection |
| Clots | Rare, small | Frequent, larger than 2 to 3 cm (size of a 2-euro coin) |
| Leakage | Exceptional | Clothing or sheets stained despite precautions |
| Impact on life | None | Cancelled outings, work or sports prevented, anxiety related to leakage |
| Menstrual cup (if used) | Less than 80 mL total over the cycle | More than 80 mL total (cup graduations) |
Two or more criteria in the right column, over several cycles, are sufficient to speak of heavy menstruation and to justify medical evaluation. The graduated menstrual cup is the only simple way to actually measure volume.
3. Why we don't realize it
Heavy menstruation is very common in women of reproductive age and is a major factor in iron deficiency and iron-deficiency anemia. Its connection is poorly appreciated and frequently normalized by society, healthcare professionals, and women themselves. Both affect quality of life: menstruation during bleeding, deficiency on a daily basis, with impact on cognitive function, absenteeism, and performance at work or school. The authors call for systematic screening.
Munro MG, Mast AE, Powers JM, et al. Am J Obstet Gynecol 2023;229(1):1-9. DOI : 10.1016/j.ajog.2023.01.017
The cycle is vicious: iron deficiency causes fatigue, fatigue reduces activity, and iron deficiency itself, by disrupting coagulation and uterine function, can worsen bleeding. The symptoms of deficiency—persistent fatigue, shortness of breath, hair loss, brittle nails, restless legs in the evening, feeling cold, difficulty concentrating—are detailed in low ferritin: what to do. In a woman who meets two criteria from the previous checklist, these should suggest iron deficiency before anything else.
4. The causes of heavy periods
Gynecologists classify causes into two categories. Structural causes : fibroids (present in one in three women after age 35, not always responsible), endometrial polyps, adenomyosis, and more rarely a lesion requiring biopsy. Non- structural causes: ovulation disorders (perimenopause, puberty, polycystic ovary syndrome, hypothyroidism), coagulation disorders (von Willebrand disease affects 1% of the population and often presents with heavy periods from puberty onward), copper IUD, anticoagulants, and localized endometrial dysfunction with no visible cause (Petraglia et Dolmans, Fertil Steril, 2022). Endometriosis, for its part, more often causes painful rather than heavy periods, but the two frequently coexist; our article endometriosis: symptoms and management covers this thoroughly.
5. The testing to request
- Ferritin : iron reserves. Below 30 µg/L, deficiency is established; below 50 with fatigue, it warrants correction (Vaucher, CMAJ, 2012).
- CRP : inflammation, which raises ferritin falsely. Always request it at the same time.
- Hemoglobin, MCV : to determine if anemia is present (hemoglobin below 12 g/dL), in which case treatment is prescribed.
- TSH : hypothyroidism lengthens and worsens periods.
- Gynecological examination and pelvic ultrasound : fibroids, polyps, adenomyosis, endometrial thickness.
- Coagulation panel (PT, aPTT, von Willebrand factor, platelets): if periods have been heavy since puberty, in case of family history or easy bleeding elsewhere.
Ferritin testing is preferably done outside of menstruation, and away from infection or intense exercise. If you are already taking iron, mention it: the result then reflects the treatment, not the baseline state.
6. Compensate each month
14 mg of iron chelated with glycine, 80 mg of vitamin C already in the capsule, 200 µg of vitamin B9 (useful for any woman of childbearing age). Absorbed, well-tolerated, with no metallic taste or constipation: the iron you can take every month without thinking about it. Made in France.
Discover Bisglycinate Iron →Not recommended in case of hemochromatosis, during pregnancy and breastfeeding without medical advice. Also explore our female comfort.
7. Treat the source
As long as the source is not treated, compensation is a losing battle. The options, all medical, are well established:tranexamic acid during menstruation, which reduces volume by 30 to 50%; nonsteroidal anti-inflammatory drugs, which reduce it by 20 to 40% and relieve pain; combined or progestin-only pill; levonorgestrel IUD, which reduces bleeding by 70 to 90% and has become a first-line treatment for heavy periods; and depending on the cause, treatment of fibroids (medications, embolization, myomectomy) or polyps (hysteroscopy). Von Willebrand disease or hypothyroidism are treated in their own right. The choice depends on the cause, age, desire for pregnancy and contraindications: it's a discussion with your gynecologist, not a blog article.
For women with endometriosis or adenomyosis, comprehensive cycle management, including pain, is detailed in our dedicated article, and our formula Endometrine is part of supporting menstrual comfort, as a complement to medical monitoring.
8. When to seek care without delay
You soak through a pad per hour for more than two hours, or you experience dizziness, heart palpitations, or shortness of breath at rest: this may indicate severe bleeding or anemia.
You bleed between periods, after intercourse, or after menopause : these bleeds should always be examined.
Your periods have become heavy after age 45, or are accompanied by new pain, abdominal bloating, or frequent urination.
Your hemoglobin is low (less than 12 g/dL): anemia requires prescribed treatment, sometimes intravenous, and investigation of the cause.
You are pregnant or trying to become pregnant with low ferritin: iron deficiency in early pregnancy has consequences for the child (Munro 2023); correction should be decided with your doctor or midwife.
Choose the situation that matches yours: the answer appears just below.
Request ferritin, CRP, and hemoglobin levels. If below 50 with fatigue, a well-tolerated iron supplement such as Bisglycinate iron, in the morning on an empty stomach, for 3 months, then retest. And track a cycle using the chart in section 2: if two criteria are checked, schedule an appointment with a gynecologist to investigate the cause.
First verify your intake: morning on an empty stomach, with vitamin C, keep tea, coffee, and dairy products 2 hours apart, single dose, every other day if the dose is high. If digestive side effects make you stop, switch to bisglycinate. If ferritin still doesn't rise after 3 months, losses exceed absorption: the source must be treated with your gynecologist, and intravenous iron should be discussed.
This picture suggests a coagulation disorder, most often von Willebrand disease, which affects 1% of the population and often goes unnoticed. Ask your doctor for testing (PT, PTT, von Willebrand factor, platelets). Management of periods and iron follows from this.
A recent change should be examined: pelvic ultrasound to check for fibroids, polyps, or adenomyosis, TSH, and after age 45 endometrial evaluation. With a copper IUD, increased volume is expected; if ferritin drops, a hormonal IUD can be discussed. Supplement iron in parallel, not instead.
This test provides guidance; it does not replace professional medical advice.
Frequently asked questions about heavy periods and iron
At what point are periods considered heavy?
The medical definition is loss greater than 80 mL per cycle, but no one measures it. Practical criteria: periods lasting more than 7 days, pad changes every hour or two for several hours, need to double protection or get up at night, clots larger than 2 to 3 cm, and impact on daily life.
How much iron is lost during a period?
One milliliter of blood contains approximately 0.5 mg of iron. A normal cycle (30 to 60 mL) costs 15 to 30 mg; heavy menstrual bleeding (more than 80 mL) costs 40 mg and more, sometimes over 100 mg. With absorption rates of 10 to 15%, you need to consume 300 to 700 mg of iron per month to compensate, which diet alone often cannot provide.
Do heavy periods necessarily cause anemia?
Not necessarily anemia, but very often iron deficiency without anemia, whose symptoms (fatigue, hair loss, shortness of breath, poor concentration) are already present. Anemia occurs when reserves have been depleted for a long time. Both situations warrant ferritin testing.
What tests should be ordered in case of heavy periods?
Ferritin, CRP, and hemoglobin for iron; TSH for thyroid; a gynecological exam with ultrasound to look for fibroids, polyps, or adenomyosis; and, if periods have been heavy since puberty or if you bleed easily otherwise, a coagulation profile (von Willebrand disease).
Does a copper IUD increase the risk of iron deficiency?
Yes. The copper IUD increases menstrual volume by 20 to 50% on average, especially in the first year. Ferritin monitoring is recommended. Conversely, the hormonal IUD reduces bleeding by 70 to 90% and is part of heavy menstrual bleeding treatments.
How do you compensate for iron loss each month?
Through a diet rich in heme iron and vitamin C, and, if ferritin is low, through continuous iron supplementation that is well tolerated (bisglycinate with vitamin C), taken in the morning away from tea, coffee, and dairy products. Some women prefer to increase supplementation during menstruation week and the following week; what matters is consistency over several months.
Should you take iron during or after your period?
Both work, as long as you maintain it consistently. Continuous daily supplementation is easiest to follow. If you opt for increased dosing, start on the first day of your period and continue for two weeks. Correcting low ferritin requires 3 to 6 months in any case.
What treatments exist to reduce heavy periods?
Tranexamic acid during menstruation, anti-inflammatory drugs, hormonal contraception (pill, levonorgestrel IUD), and depending on the cause, treatment of fibroids or polyps. These are medical decisions made with your gynecologist or primary care doctor. Iron corrects the consequence, not the cause.
Are heavy periods normal approaching menopause?
They are common in perimenopause due to anovulatory cycles, but they are not harmless: this is the period when iron deficiency often develops, and any unusual bleeding after age 45 should be examined to rule out a uterine cause.
When should you seek emergency care for heavy periods?
Bleeding that saturates a pad per hour for more than 2 hours, dizziness, heart palpitations or shortness of breath at rest, bleeding between periods or after intercourse, bleeding after menopause, or heavy periods with unusual pain. In these cases, consult without delay.
- Menorrhagia
- Medical term for heavy menstrual bleeding: more than 80 mL per cycle or lasting more than 7 days.
- Ferritin
- Iron storage protein; its blood concentration reflects iron reserves, except in cases of inflammation.
- Adenomyosis
- Presence of endometrial tissue in the uterine muscle, a common cause of heavy and painful periods after age 35.
- Von Willebrand Disease
- Hereditary coagulation disorder (1% of the population), often revealed by heavy periods from puberty onward.
- Tranexamic Acid
- Medication taken during menstruation that reduces bleeding volume by 30 to 50%, by prescription.
- 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. doi:10.1016/j.ajog.2023.01.017
- Cappellini MD, Santini V, Braxs C, Shander A. Iron metabolism and iron deficiency anemia in women. Fertil Steril. 2022;118(4):607-614. doi:10.1016/j.fertnstert.2022.08.014
- Petraglia F, Dolmans MM. Iron deficiency anemia: impact on women's reproductive health. Fertil Steril. 2022;118(4):605-606. doi:10.1016/j.fertnstert.2022.08.850
- Pasricha SR, Tye-Din J, Muckenthaler MU, Swinkels DW. Iron deficiency. Lancet. 2021;397(10270):233-248. doi:10.1016/S0140-6736(20)32594-0
- Lopez A, Cacoub P, Macdougall IC, Peyrin-Biroulet L. Iron deficiency anaemia. Lancet. 2016;387(10021):907-916. doi:10.1016/S0140-6736(15)60865-0
- Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247-1254. doi:10.1503/cmaj.110950
- 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. Lancet Haematol. 2017;4(11):e524-e533. doi:10.1016/S2352-3026(17)30182-5
- Fischer JAJ, Cherian AM, Bone JN, Karakochuk CD. The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis. Nutr Rev. 2023;81(8):904-920. doi:10.1093/nutrit/nuac106
- ANSES. Nutritional reference values for vitamins and minerals (2021). anses.fr
