Introduction
You may think of a heavy period as something you simply have to endure.
But if you are losing a significant amount of blood every month, your body is losing iron along with it. Over time, your iron stores can become depleted — sometimes before your haemoglobin falls enough to be called anaemia. 1
That can leave you feeling tired, foggy or unusually weak without immediately understanding why.
And no, you don’t have to wait until you are severely anaemic before asking for help.
How do heavy periods cause iron deficiency?
Your body needs iron to make haemoglobin, the protein in red blood cells that carries oxygen around your body.
Every menstrual period involves some blood loss. When bleeding is particularly heavy or prolonged, the amount of iron lost can become greater than what your body can replace through food and normal iron absorption. Over time, this can deplete iron stores and may eventually contribute to iron-deficiency anaemia.
Over time, the sequence can look something like this:
Iron stores fall → iron deficiency develops → haemoglobin may eventually fall → iron-deficiency anaemia
The important part is that iron deficiency can exist without anaemia. 1 2
So a normal haemoglobin result does not always mean your iron stores are healthy.
What might iron deficiency feel like?
Iron deficiency can be surprisingly subtle.
You may notice:
- Tiredness that doesn’t seem to match your activity
- Feeling weak or drained
- Poor concentration or “brain fog”
- Headaches
- Reduced exercise tolerance
- Breathlessness with activity
- Dizziness or light-headedness
- Feeling unusually cold
- Restless legs
- Craving or wanting to chew non-food substances such as ice, known as pica 2
You don’t need to have every symptom.
And fatigue has many possible causes — poor sleep, thyroid problems, stress, infections, inadequate nutrition and several medical conditions can all make you tired. These symptoms alone cannot diagnose iron deficiency.
That persistent tiredness is not always “just part of being busy” or something you have to accept as a normal part of having periods. Iron deficiency may contribute to fatigue and reduced day-to-day functioning, but fatigue has many possible causes and the evidence linking iron deficiency with fatigue in women of childbearing age is still limited. 3 This is one reason heavy menstrual bleeding deserves attention even when your haemoglobin has not yet fallen into the anaemia range.
Could you have low iron even if your haemoglobin is normal?
Yes.
This is one of the most important things to understand.
Ferritin is a blood marker that reflects your body’s iron stores. It can help identify depleted iron stores even when haemoglobin is still normal. The WHO recommends ferritin as an important marker for assessing iron status, while also noting that inflammation can raise ferritin and complicate interpretation. 4
This is why your doctor may consider both a complete blood count (CBC) and serum ferritin, rather than looking at haemoglobin alone.
If inflammation or another condition is present, your doctor may need additional tests to interpret the result correctly. 4
What does this mean for Indian women?
Iron deficiency deserves particular attention in India.
Analysis of India’s Comprehensive National Nutrition Survey, involving 14,673 adolescents aged 10–19, found anaemia in approximately 40% of girls compared with 18% of boys. Iron deficiency, defined in that study using ferritin below 15 μg/L, was the strongest predictor of anaemia. 5
More recent Indian evidence continues to show the problem. A 2026 study of 750 adolescent girls in Gujarat found 39.6% had anaemia, while 54.5% met the study’s definition of latent iron deficiency — low ferritin despite normal haemoglobin. 6
These studies do not mean that heavy periods are responsible for all anaemia in Indian women and girls. Diet, infections, inflammation, inherited blood conditions and other nutritional deficiencies can also contribute. But menstrual blood loss is an important, potentially overlooked source of iron loss.
The wider Indian context makes this worth taking seriously. National data compiled in the Government of India’s National Health Profile report that around 57% of women aged 15–49 years were anaemic, with the burden remaining substantial among both non-pregnant and pregnant women. 7 Anaemia is not caused by iron deficiency alone—dietary insufficiency, infections, inflammation, inherited blood disorders and other conditions can contribute—but menstrual blood loss is an important potential contributor in women who have heavy or prolonged periods.
A simple check-in
Think about your last few periods.
- How many days did you bleed?
- Were you changing your pad every one or two hours?
- Did you leak through clothes or bedsheets?
- Did you feel exhausted during or after your period?
- Have you been craving ice or other non-food substances?
- Are you increasingly struggling with exercise, concentration or everyday tasks?
If several answers are yes, don’t simply assume that you need “more energy” or another supplement. It may be worth discussing your periods and iron status with a doctor.
What tests might your doctor recommend?
The exact evaluation depends on your age, symptoms and medical history.
Your doctor may consider:
- CBC — checks haemoglobin and other blood-cell measurements
- Serum ferritin — assesses iron stores
- Other iron studies where appropriate
- Tests for causes of heavy menstrual bleeding when indicated 1 4
The bigger question is not just “How do I replace the iron?”
It is also: “Why am I losing so much iron?”
What causes heavy periods?
If heavy periods are the cause, treating the iron deficiency without addressing the excessive bleeding may allow the problem to keep returning. Heavy menstrual bleeding can have several causes, including irregular ovulation, PCOS/PMOS, thyroid disorders, fibroids, certain medicines and bleeding disorders. The possible causes vary with age and individual circumstances. 1
Should you get your iron levels checked?
If you have repeatedly heavy periods, persistent fatigue, weakness, dizziness, breathlessness or other symptoms that concern you, it is worth discussing your symptoms and iron status with a doctor.
Your doctor can decide whether blood tests such as a CBC and ferritin are appropriate and help identify whether heavy menstrual bleeding may be contributing to iron deficiency.
Food can help — but it may not be enough on its own
Include iron-rich foods such as:
- Lentils and dals
- Beans and chickpeas
- Green leafy vegetables
- Sesame and other seeds
- Eggs
- Meat, fish or poultry if you eat them
Pairing plant sources of iron with vitamin-C-rich foods can improve absorption. But if you already have significant iron deficiency or anaemia, food alone may not restore your iron stores quickly enough. Treatment should be guided by the severity and cause of the deficiency.
When should you see a doctor?
Please arrange an evaluation if you have:
- Repeatedly heavy or prolonged periods
- Persistent fatigue or weakness
- Breathlessness or dizziness
- Fainting or significant paleness
- Difficulty concentrating that is affecting daily life
- Pica, such as persistent ice craving
- Previously diagnosed anaemia that keeps returning
Seek urgent medical care if you are soaking through a pad or tampon every hour for several hours in a row, especially if you also have fainting, severe dizziness, marked weakness, breathlessness, chest symptoms, a racing heartbeat or feel medically unwell. You don’t have to wait until you “look anaemic” to ask for help.
Key Takeaways
- Heavy periods can gradually deplete your body’s iron stores.
- Iron deficiency can occur before anaemia develops.
- Fatigue, poor concentration, weakness, breathlessness and pica can be clues, but they are not specific to iron deficiency. 2 3
- A CBC and ferritin may help your doctor assess whether iron deficiency or anaemia is present. 1 4
- In India, iron deficiency and anaemia remain significant concerns, particularly among adolescent girls. 5 6
- Replacing iron is only part of the solution. The reason for heavy bleeding also needs to be understood.
- If your periods are taking more from you than they should, you deserve more than being told to simply “put up with it.”
- Find the cause. Check your iron. Treat what needs treating.
References
- American College of Obstetricians and Gynecologists. Screening and Management of Bleeding Disorders in Adolescents With Heavy Menstrual Bleeding. Committee Opinion No. 785. Obstetrics & Gynecology. 2019.
- Powers JM, Buchanan GR. Diagnosis and Management of Iron Deficiency Anemia. Hematology/Oncology Clinics of North America. 2014;28(4):729–745.
- Greig AJ, Patterson AJ, Collins CE, Chalmers KA. Iron deficiency, cognition, mental health and fatigue in women of childbearing age: a systematic review. Journal of Nutritional Science. 2013;2:e14.
- World Health Organization. WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. 2020.
- Scott S, Lahiri A, Sethi V, et al. Anaemia in Indians aged 10–19 years: Prevalence, burden and associated factors at national and regional levels. Maternal & Child Nutrition. 2022;18(4):e13391.
- Chaudhary SR, Gadhavi VJ, Chauhan R, et al. Anemia Prevalence and its Determinants among Adolescent Girls in Gujarat, India: A Cross-Sectional Study. Indian Journal of Community Medicine. 2026;51(3):512–519.
- Central Bureau of Health Intelligence, Directorate General of Health Services, Ministry of Health & Family Welfare, Government of India. National Health Profile 2023. New Delhi: CBHI; 2024.