Iron deficiency in women is the most widespread micronutrient deficiency in the world — yet it remains widely under-diagnosed and under-treated. Many women live with it for months or years, attributing their symptoms to stress, a busy schedule, or simply not sleeping well enough. The fatigue, the brain fog, the breathlessness after climbing a flight of stairs — these feel familiar enough to dismiss. But they are not normal. They are signals worth taking seriously.
Research published in the American Journal of Hematology in 2024 found high rates of iron deficiency among non-pregnant women of reproductive age — with significant socioeconomic disparities in who receives testing and treatment. A separate 2024 analysis of health records from 13,084 adults found that approximately 6 in 10 people diagnosed with iron deficiency still had low iron levels three years after their diagnosis. This tells us two things: iron deficiency is common, and it is frequently not treated effectively.
This article explains what iron deficiency is, which symptoms to watch for, why women are particularly vulnerable, how it is diagnosed, and what actually works to treat it.
To understand how nutrient timing and supplementation affect iron absorption specifically, read our article onThe Best Time of Day to Take Vitamins D, B12, Magnesium, and Iron
What Is Iron Deficiency in Women?
Iron deficiency in women occurs when the body’s total iron content falls below the level needed for normal function. Iron is essential for producing haemoglobin — the protein in red blood cells that carries oxygen from the lungs to every tissue and organ in the body. When iron levels fall, haemoglobin production declines. Cells receive less oxygen. The result is a cascade of symptoms that affect energy, cognition, immunity, and physical performance.
Iron deficiency exists on a spectrum:
- Iron depletion: iron stores in the body are low, but haemoglobin remains normal. Symptoms may already be present at this stage, though blood tests often appear within normal range.
- Iron deficiency without anaemia: iron stores are depleted and iron supply to tissues is insufficient, but haemoglobin has not yet fallen below the anaemia threshold. This stage is frequently missed because standard blood tests check haemoglobin rather than ferritin — the storage form of iron.
- Iron deficiency anaemia: iron stores are severely depleted and haemoglobin has fallen below the threshold for anaemia. This is the stage most commonly diagnosed and treated — often too late in the process.
A comprehensive 2025 study published in BMC Women’s Health specifically examined symptom patterns in women with non-anaemic iron deficiency. It found that women at this stage experience a significant and wide-ranging symptom burden — even before haemoglobin falls into the anaemic range. Waiting for anaemia before investigating or treating iron deficiency means missing and ignoring a great deal of preventable suffering.
Why Iron Deficiency in Women Is So Common
Women face a significantly higher risk of iron deficiency than men. Several biological and dietary factors explain this.
Menstrual blood loss
The most significant driver of iron deficiency in women of reproductive age is monthly blood loss through menstruation. Each menstrual cycle causes iron loss. For women with heavy periods — defined as losing more than 80ml of blood per cycle — this loss can far exceed what diet and absorption can replace. Heavy menstrual bleeding affects approximately 1 in 4 women and is one of the most under-recognised causes of chronic iron deficiency.
Many women with heavy periods normalise their symptoms. They assume that exhaustion, flooding through pads and tampons, and passing large clots is simply how periods work. Heavy periods are common — but they are not normal, and they are a significant driver of iron deficiency that deserves medical attention.
Pregnancy and postpartum period
Pregnancy dramatically increases iron requirements. The developing baby draws on the mother’s iron stores for its own blood and organ development. Blood volume increases by approximately 50 percent during pregnancy. Both factors mean that iron requirements roughly double during pregnancy — from 18mg per day to 27mg per day. Iron deficiency anaemia during pregnancy links to increased risks of preterm birth, low birth weight, and poorer maternal recovery after delivery, according to a 2025 retrospective cohort study published in the journal Nutrients.
Dietary intake and absorption
Iron from food comes in two forms. Haem iron — from meat, poultry, and fish — absorbs efficiently, at a rate of 15 to 35 percent. Non-haem iron — from plant foods, eggs, and dairy — absorbs at a rate of only 2 to 20 percent. Women following vegetarian or vegan diets face a higher risk of iron deficiency because their entire dietary iron intake comes from the less absorbable non-haem form.
Additionally, several substances inhibit iron absorption when consumed at the same time as iron-rich foods. Coffee, tea, calcium-rich foods, and high-fibre grains all reduce how much iron the body can absorb from a meal. Many women unknowingly eat in patterns that significantly reduce the iron they absorb from an otherwise adequate diet.
Gastrointestinal conditions
Coeliac disease, Crohn’s disease, and other inflammatory gut conditions impair iron absorption from the small intestine — even when dietary intake is adequate. Women with these conditions face elevated iron deficiency risk and often need higher supplementation doses or intravenous iron to restore levels effectively. Helicobacter pylori infection also impairs iron absorption and is a frequently missed cause of iron deficiency that does not respond to standard supplementation.
Perimenopause and menopause
Perimenopausal women often experience heavier and more irregular periods before menstruation stops. This transitional phase can worsen iron deficiency. After menopause, however, iron deficiency risk decreases significantly — and unexplained iron deficiency in a postmenopausal woman always warrants investigation for gastrointestinal blood loss rather than assumption that it is dietary or menstrual in origin.
Symptoms of Iron Deficiency in Women
The symptoms of iron deficiency in women range from subtle and easy to dismiss to severe and significantly disabling. Many women live with these symptoms for years before anyone checks their iron levels.
The most common symptoms
1. Fatigue and low energy
Fatigue is the most common and most reported symptom of iron deficiency. It is not ordinary tiredness. It is a persistent, heavy exhaustion that does not improve with sleep or rest. Cells across the body receive less oxygen when iron is low. Every physical and mental task requires more effort. Many women describe feeling like they are wading through treacle — capable of functioning but at a fraction of normal capacity.
2. Brain fog and poor concentration
The brain is highly sensitive to oxygen supply. When iron is low and oxygen delivery to brain tissue falls, cognitive function suffers. Women with iron deficiency commonly report difficulty concentrating, forgetting words mid-sentence, feeling mentally slow, and struggling to retain information. A 2025 comprehensive study in BMC Women’s Health found that cognitive symptoms — including poor concentration and memory difficulties — ranked among the most frequently reported symptoms in women with non-anaemic iron deficiency.
3. Breathlessness with minimal exertion
When haemoglobin falls, the heart works harder to deliver oxygen to tissues. Climbing stairs, walking briskly, or carrying shopping can trigger breathlessness that feels disproportionate to the activity level. Many women attribute this to being unfit rather than to iron deficiency — particularly if they are not significantly overweight.
4. Heart palpitations
The heart compensates for reduced oxygen delivery by beating faster. Palpitations — a racing, fluttering, or pounding heartbeat — are a recognised symptom of iron deficiency anaemia and can be alarming enough to prompt emergency care. In most cases, cardiac investigations come back normal because the cause is haematological rather than structural.
5. Pale skin, gums, and inner eyelids
Haemoglobin gives blood its red colour and skin its warmth. As haemoglobin levels fall, skin becomes paler — particularly noticeable in the inner lower eyelid, which should be a healthy pink-red. Pale gums and a pale crease on the palm of the hand are also clinical signs that healthcare professionals check when assessing for anaemia.
6. Hair loss and brittle nails
Iron supports hair follicle function and nail keratin production. Deficiency causes the body to prioritise iron delivery to essential organs — and hair follicles and nails are deprioritised. Significant hair shedding — particularly diffuse thinning across the scalp rather than patchy loss — is a common and distressing symptom of iron deficiency that many women never connect to their iron levels.
7. Restless legs syndrome
An uncomfortable urge to move the legs — particularly at night, worsening with rest and improving with movement — is a recognised symptom of iron deficiency. Research published in PubMed confirms that iron deficiency, even without anaemia, links to restless legs syndrome. Iron plays a role in dopamine metabolism in the brain, and low iron disrupts the dopamine pathways involved in movement control.
8. Pica — cravings for non-food substances
One of the lesser-known but well-documented symptoms of iron deficiency is pica — an intense craving for non-food substances such as ice, clay, chalk, or paper. Ice craving in particular, known as pagophagia, is strongly associated with iron deficiency and often resolves quickly once iron levels are restored. Many women experience ice craving for months before anyone identifies iron deficiency as the cause.
9. Frequent infections
Iron plays a critical role in immune function. White blood cells require iron to replicate and respond effectively to infection. Women with iron deficiency experience more frequent respiratory infections and slower recovery from illness than those with adequate iron levels.
10. Headaches and dizziness
Reduced oxygen delivery to the brain can cause persistent headaches and light-headedness — particularly on standing quickly. These symptoms are common in iron deficiency and frequently attributed to dehydration or stress rather than to low iron.
How Iron Deficiency in Women Is Diagnosed
Diagnosing iron deficiency in women accurately requires more than a standard full blood count. Haemoglobin — the measure most commonly checked — does not fall below normal until iron deficiency is already significantly advanced. Many women with significant symptoms and depleted iron stores are told their blood tests are normal because only haemoglobin was measured.
The tests that matter
- Serum ferritin: ferritin measures iron stores — not circulating iron. It is the most sensitive marker for iron deficiency at an early stage. A ferritin level below 30 micrograms per litre is consistent with depleted iron stores. Some researchers and clinicians use a threshold of 50 to 70 micrograms per litre as the target for women with symptoms, particularly those with fatigue or hair loss.
- Serum iron and transferrin saturation: these measure circulating iron and how much of the transport protein transferrin is carrying iron. Low transferrin saturation alongside low ferritin confirms iron deficiency.
- Full blood count: checks haemoglobin, mean corpuscular volume (MCV), and red blood cell appearance. Small, pale red blood cells suggest iron deficiency anaemia — but this finding only appears once deficiency is established.
- C-reactive protein (CRP): ferritin is an acute phase protein — it rises during inflammation regardless of iron status. Checking CRP alongside ferritin helps distinguish true iron deficiency from falsely elevated ferritin due to inflammation.
If you have symptoms of iron deficiency but have been told your blood tests are normal, ask specifically whether your ferritin was checked — and what the result was. A haemoglobin within normal range does not rule out iron deficiency.
How to Treat Iron Deficiency in Women
Treatment for iron deficiency in women depends on the severity of deficiency, the underlying cause, and how well oral supplementation is tolerated.
Dietary changes
Increasing dietary iron intake supports treatment — but rarely resolves established deficiency on its own. Focus on:
- Haem iron sources: red meat, lamb, liver, chicken, turkey, and oily fish. These provide the most efficiently absorbed form of iron.
- Non-haem iron sources: lentils, beans, chickpeas, tofu, dark leafy greens, fortified cereals, seeds, and dried fruit. These provide useful amounts of iron but require pairing with vitamin C to maximise absorption.
- Vitamin C with iron-rich meals: adding a glass of orange juice, a squeeze of lemon, or vitamin C-rich vegetables — peppers, broccoli, kiwi — to iron-containing meals increases non-haem iron absorption significantly.
- Avoiding absorption inhibitors at iron-rich meals: coffee, tea, calcium-rich dairy, and high-phytate foods all reduce iron absorption when consumed at the same time as iron-rich foods. Space these at least one hour away from iron-rich meals where possible.
Oral iron supplementation
Oral iron supplements are the first-line treatment for iron deficiency. However, standard ferrous sulphate supplements cause gastrointestinal side effects — constipation, nausea, and stomach discomfort — in many women. These side effects are one of the most common reasons women stop taking iron supplements before their levels are restored.
Several strategies improve tolerability:
- take iron on alternate days rather than daily — research shows that alternate-day dosing achieves similar iron restoration with significantly fewer side effects
- take iron with a small amount of food if stomach discomfort is significant — this reduces absorption slightly but improves the likelihood of consistent use
- try ferrous bisglycinate or ferrous gluconate formulations — these gentler forms cause fewer gastrointestinal side effects than ferrous sulphate
- take iron with vitamin C — either orange juice or a separate vitamin C supplement — to maximise absorption
- avoid taking iron alongside calcium supplements, antacids, or within an hour of coffee or tea
Intravenous iron infusion
For women who cannot tolerate oral iron, whose deficiency is severe, or whose underlying condition impairs gut absorption — such as coeliac disease or inflammatory bowel disease — intravenous iron infusion restores iron levels rapidly and effectively. It bypasses the gut entirely and delivers iron directly into the bloodstream. Side effects are uncommon with modern formulations. A single infusion can restore iron stores to adequate levels within days to weeks.
Treating the underlying cause
Supplementation alone is insufficient if the underlying cause of iron loss or poor absorption is not addressed. Heavy menstrual bleeding should be investigated and managed — hormonal treatment, an intrauterine device, or further gynaecological evaluation may be appropriate. Coeliac disease requires a strict gluten-free diet. Helicobacter pylori infection requires eradication treatment. Identifying and addressing the cause is the only way to achieve sustainable iron restoration rather than a temporary improvement followed by relapse.
When to See a Doctor About Iron Deficiency
See your GP if:
- you have persistent fatigue, brain fog, breathlessness, or hair loss that has not improved with rest
- you experience heavy periods — soaking through pads or tampons every hour, passing large clots, or bleeding for more than seven days
- you are pregnant or planning a pregnancy and have not had your iron levels checked recently
- you follow a vegetarian or vegan diet and have symptoms of iron deficiency
- you have been diagnosed with iron deficiency and are not improving after three months of supplementation
- you experience palpitations, significant breathlessness, or chest tightness — these warrant urgent assessment
Ask your doctor to check your serum ferritin specifically — not just your haemoglobin. A ferritin level is the earliest and most reliable indicator of iron deficiency before anaemia develops.
For more on women’s health conditions that frequently co-exist with iron deficiency, read our article on Perimenopause at 40: The 10 Unexpected Symptoms No One Talks About.
The NHS guide to iron deficiency anaemia provides comprehensive information on symptoms, diagnosis, treatment, and when to seek medical advice.
Key Takeaways
- Iron deficiency in women is the most common micronutrient deficiency worldwide and remains significantly under-diagnosed — particularly in the non-anaemic stage before haemoglobin falls.
- A 2024 analysis found that 6 in 10 people diagnosed with iron deficiency still had low levels three years later — meaning effective treatment is also frequently lacking.
- Key symptoms include persistent fatigue, brain fog, breathlessness, palpitations, hair loss, pale skin, restless legs, pica, and frequent infections — many of which women normalise for years.
- Serum ferritin is the most sensitive early marker of iron deficiency. A normal haemoglobin does not rule out iron deficiency — always ask specifically for ferritin to be checked.
- Haem iron from meat and fish absorbs far more efficiently than non-haem iron from plant sources. Pairing non-haem iron foods with vitamin C significantly improves absorption.
- Alternate-day oral iron dosing reduces gastrointestinal side effects while achieving similar iron restoration to daily dosing — making it easier to sustain treatment until levels are restored.
- Treating the underlying cause — heavy periods, coeliac disease, Helicobacter pylori, or poor absorption — is essential for sustainable recovery rather than temporary improvement.
Final Thoughts
The tiredness you have been pushing through, the brain fog you have blamed on a busy life, the hair coming out in the shower, the breathlessness climbing stairs — these things are not inevitable. For many women, they are the entirely treatable consequences of iron deficiency that nobody has yet identified or addressed.
You do not have to wait until you feel dramatically unwell to ask for a blood test. If several of the symptoms in this article sound familiar, a simple ferritin blood test could give you the explanation you have been missing and open the door to treatment that genuinely makes a difference.
Ask for the ferritin test. Do not accept “your bloods are normal” as a complete answer if the haemoglobin was the only thing checked. Advocate for yourself — because iron deficiency in women is common, treatable, and far too often missed.
Medical Disclaimer: The information on this page is provided for educational and informational purposes only and is not intended as medical advice. It should not replace consultation with a qualified healthcare professional. For full details, please read our Disclaimer.
