Iron Deficiency in Women: Symptoms, Causes and When to Get Tested

You may be sleeping for eight hours and still feel as though you are dragging a weight through the day. Headaches keep returning, stairs leave you breathless or concentration feels harder than usual. Iron deficiency in women is one possible reason, especially if you have heavy periods, recently had a baby or eat very few iron-rich foods. But tiredness alone cannot confirm low iron, which is why symptoms, risk factors and the right blood tests all matter.

What does iron deficiency in women actually mean?

Iron deficiency begins when the body’s iron stores become depleted. This can happen before haemoglobin falls enough for anaemia to develop. A clinical review by Balendran and Forsyth explains why haemoglobin alone can miss iron deficiency before anaemia appears.

• Iron deficiency without anaemia: Iron stores are low, but haemoglobin may still be within the normal range.

• Iron-deficiency anaemia: Iron depletion has progressed far enough to reduce haemoglobin and affect normal red blood-cell production.

Ferritin is commonly used as a marker of stored iron. The World Health Organization (WHO) considers ferritin useful for assessing iron stores, but it can rise during infection or inflammation, so the result needs to be interpreted in context.

What causes iron deficiency in women?

Being a woman does not automatically mean you will develop iron deficiency. Risk rises when iron losses or requirements become greater than the amount your body absorbs.

Heavy periods

Heavy menstrual bleeding is one of the most important causes. The American College of Obstetricians and Gynecologists (ACOG) notes that bleeding lasting more than seven days, soaking through pads or tampons very quickly, needing more than one menstrual product at a time or passing large clots can be signs of heavy menstrual bleeding. A 2023 review by Munro and colleagues describes the close relationship between heavy menstrual bleeding, iron deficiency and iron-deficiency anaemia.

Pregnancy and childbirth

Pregnancy increases iron requirements because the body makes more blood while also supporting the placenta and developing baby. The World Health Organization recommends daily oral iron and folic acid supplementation as part of antenatal care in many settings. Blood loss during childbirth can reduce iron stores further.

Diet, absorption and other blood loss

Other causes include eating too few reliable iron sources, coeliac disease, inflammatory bowel disease, previous stomach or intestinal surgery, frequent blood donation, recent surgery and slow blood loss from the digestive tract. If tests confirm low iron, replacing it is only part of the job. The reason it became low also needs to be understood.

What are the symptoms of low iron in women?

Early iron deficiency may cause no obvious symptoms. As iron stores fall, some people notice persistent tiredness, lower stamina, headaches or difficulty concentrating. Once anaemia develops, breathlessness, dizziness and a racing heartbeat may become more noticeable.

Possible symptoms include:

• Persistent fatigue or weakness

• Reduced stamina

• Breathlessness or a racing heartbeat

• Headaches, dizziness or light-headedness

• Difficulty concentrating or “brain fog”

• Diffuse hair shedding or brittle nails

• Pica, including an urge to chew ice, clay or other non-food substances

• Restless legs, a sore tongue or cracks at the corners of the mouth

These symptoms are not specific to iron deficiency. Poor sleep, thyroid disorders, vitamin B12 deficiency, infection and other conditions can cause similar problems. Severe breathlessness, chest pain or fainting needs urgent medical attention.

When should you get tested for iron deficiency?

Testing is worth discussing when persistent tiredness occurs alongside heavy periods, pregnancy or recent childbirth, a restricted diet, repeated blood donation, digestive symptoms or another risk factor for iron loss or poor absorption.

Full blood count

A full blood count (FBC) checks haemoglobin and other red-cell measurements. It can show whether anaemia is present, but normal haemoglobin does not rule out early iron deficiency. The National Institute for Health and Care Excellence (NICE) recommends a full blood count for women with heavy menstrual bleeding.

Ferritin and other iron tests

Serum ferritin is commonly used when iron deficiency is suspected because it reflects stored iron. Ferritin can be affected by inflammation or infection, so it should not always be read on its own. Transferrin saturation may provide extra information when ferritin is difficult to interpret. NICE does not recommend routine ferritin testing for every woman with heavy menstrual bleeding. The exact tests depend on your symptoms, history and why iron deficiency is suspected.

Can food help improve low iron?

Iron-rich foods are important for preventing deficiency and supporting recovery, but diet alone may not be enough once iron stores are substantially depleted or iron-deficiency anaemia has developed. Haem iron from meat, poultry and fish is generally absorbed more readily. Non-haem iron comes from foods such as lentils, rajma, chana, tofu, leafy vegetables, pumpkin seeds and fortified foods. The National Institutes of Health (NIH) Office of Dietary Supplements notes that vitamin C can improve non-haem iron absorption. Simple combinations include dal with lemon, chana with tomatoes or capsicum, or fruit such as guava or orange alongside a meal. Tea and coffee contain polyphenols that can reduce non-haem iron absorption when taken with a meal. In a controlled trial in healthy women, drinking tea one hour after an iron-containing meal reduced this effect compared with drinking tea with the meal. You do not need to stop tea or coffee completely, but timing can matter if your iron is low.

Should you take iron without testing?

Do not start a high-dose iron supplement simply because you feel tired. The National Institutes of Health Office of Dietary Supplements notes that supplemental iron can cause nausea, constipation and abdominal discomfort, while excessive intake can cause more serious harm. Self-treatment can also delay investigation of heavy menstrual bleeding, digestive blood loss, poor absorption or another cause of fatigue. There are situations where iron is routinely recommended, including pregnancy or recognised public-health programmes, but those recommendations should be followed as directed.

What happens if tests confirm low iron?

Treatment depends on how low your iron is and why it became low. A doctor may recommend dietary changes, prescribe oral iron, investigate heavy menstrual bleeding or look for a condition affecting absorption or causing blood loss. Follow-up blood tests may be used to check whether haemoglobin and iron stores are recovering. Do not stop prescribed treatment as soon as you feel better unless advised, because symptoms can improve before iron stores are fully replenished.

When should you get urgent medical help?

Seek urgent medical care for chest pain, severe breathlessness or breathlessness at rest, fainting, a very fast or irregular heartbeat with weakness or dizziness, black or bloody stools, or extremely heavy bleeding that is difficult to control. Arrange a medical appointment promptly if fatigue continues for several weeks, your periods become much heavier, you feel persistently dizzy or you develop pica.

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Sources

• World Health Organization: Guideline on ferritin concentrations and iron status

• American College of Obstetricians and Gynecologists: Heavy Menstrual Bleeding

• National Institute for Health and Care Excellence: Heavy menstrual bleeding

• National Institutes of Health Office of Dietary Supplements: Iron

• Balendran S, Forsyth C. Non-anaemic iron deficiency. Australian Prescriber. 2021.

• Fuzi SFA, et al. Tea timing and non-haem iron absorption. American Journal of Clinical Nutrition. 2017.

Medical Disclaimer: This article is for general educational purposes only and should not replace professional medical advice, diagnosis or treatment. If you have persistent fatigue, heavy menstrual bleeding, breathlessness, dizziness or think you may have iron deficiency, speak with a qualified healthcare professional for appropriate testing and treatment.