Iron, and why so many women run low

Why this matters

You may be wondering about iron because you feel unusually tired, have heavy periods, eat little or no meat, or have been told that your blood count is low. These are reasons to look more closely, but symptoms alone cannot show whether iron is the cause.

Iron helps your body make haemoglobin, the part of red blood cells that carries oxygen. Iron deficiency happens when stored iron runs down. If it progresses, you can develop iron-deficiency anaemia, meaning you do not have enough healthy, oxygen-carrying red blood cells. Stores can be low before anaemia develops.

Women often run low because iron leaves the body through blood. Menstrual bleeding is a common reason, especially when periods are heavy or prolonged. Pregnancy also increases iron needs.

Risk is shaped more by menstruation, pregnancy and blood loss than by gender identity. Other causes include frequent blood donation, a diet low in available iron, coeliac disease, inflammatory bowel disease, previous stomach or bowel surgery, or digestive-tract bleeding.

After menopause, new iron deficiency is less likely to be explained by menstrual loss and usually deserves medical assessment.

What the evidence says

The evidence is strong that confirmed iron deficiency should be treated. Replacing missing iron can restore stores and improve iron-deficiency anaemia.

The evidence does not support every woman taking an iron supplement. Iron is unlikely to improve energy, concentration or fitness if you are not deficient. It may cause side effects and delay investigation of the real reason you feel unwell.

A full blood count measures haemoglobin and features of your blood cells. A ferritin test estimates stored iron. Low ferritin usually supports iron deficiency, but infection or inflammation can raise ferritin, so a normal-looking result does not always settle the question.

For fatigue without anaemia, the evidence is mixed. Some people with low stores may feel less fatigued after treatment, but the average benefit is modest and not everyone improves.

Evidence for iron as a general hair-growth treatment is thin. Deficiency can contribute to hair shedding, but iron will not correct hair loss caused by another condition. Claims that it “boosts” energy or performance in people with adequate stores are unsupported.

Meat, fish and poultry contain haem iron, which is absorbed relatively easily. Beans, lentils, tofu, nuts, seeds, leafy vegetables and fortified cereals contain less readily absorbed non-haem iron but still contribute.

Treatment does not explain why iron became low. Blood loss, poor absorption or another illness may also need attention.

What to try

Start by considering your risk rather than buying a supplement.

This week, you could:

• Note whether your periods have become heavier, longer or more frequent
• Include an iron-containing food in regular meals
• Pair plant sources with vitamin C-rich food, such as peppers or fruit
• Check whether cereals or breads are fortified with iron
• Arrange a medical review if symptoms or risk factors persist

Tea and coffee reduce absorption of non-haem iron when taken with meals. You need not avoid them, but having them at another time may help if you rely mainly on plant sources.

If you are pregnant, planning pregnancy or have recently given birth, ask your maternity team whether testing or an iron-containing prenatal supplement is appropriate (prenatal vitamins). Pregnancy-related tiredness should not automatically be assumed to be iron deficiency.

Do not start long-term tablets only because you feel tired. Testing can show whether iron is low, provide a baseline for follow-up and help avoid overlooking thyroid problems, sleep difficulties, depression, vitamin deficiencies, infection or other causes.

If a clinician recommends iron, ask how and when your response will be checked. Tablets commonly cause nausea, stomach discomfort, constipation or diarrhoea and can darken stools.

Iron can interfere with some medicines, including certain antibiotics and thyroid replacement. Ask a pharmacist about safe timing. Keep all iron products away from children because accidental poisoning can be severe.

What to watch for

Book a routine appointment for ongoing fatigue, headaches, reduced exercise tolerance, restless legs, unusual cravings for ice or non-food items, or repeated heavy periods. These symptoms do not prove deficiency, but they make assessment reasonable.

You should also arrange follow-up if:

• A blood test has shown low haemoglobin or ferritin
• You repeatedly need iron after treatment ends
• You have digestive symptoms, unexplained weight loss or difficulty swallowing
• You are past menopause and develop iron deficiency
• Your periods disrupt daily life or have clearly changed

Seek urgent medical advice for worsening shortness of breath, a persistently racing heartbeat, marked weakness, or bleeding during pregnancy.

Call emergency services for chest pain, difficulty breathing at rest, fainting, vomiting blood, uncontrolled bleeding, or black, sticky stools with weakness or dizziness. Iron tablets can darken stools, but tar-like stools accompanied by illness may indicate digestive bleeding.

Common questions

Can I know that I am low in iron from my symptoms?

No. Tiredness, breathlessness, headaches and poor concentration have many possible causes. Blood tests are needed to clarify what is happening.

Do heavy periods always cause iron deficiency?

No, but they increase the chance. If you often bleed through period products, change them overnight, pass large clots, or avoid activities because of bleeding, discuss this at a routine appointment. Treating the bleeding may be as important as replacing iron.

Is food enough to correct low iron?

Food supports long-term intake, but may not replace depleted stores quickly enough when deficiency is established. The right approach depends on test results, symptoms, absorption and the cause.

Is an iron supplement harmless?

No. Side effects commonly affect the stomach and bowel. Too much iron can be harmful, particularly for people with iron-overload conditions such as haemochromatosis. Supplements should not be used as an open-ended energy remedy.

What if iron treatment does not help?

The diagnosis may be wrong, tablets may not be absorbed or tolerated, blood loss may be continuing, or another condition may be contributing. This calls for follow-up rather than simply taking more iron.