Iron deficiency anemia: signs, tests and treatment

In short

• Iron deficiency is the most common cause of anemia. It means your body lacks the iron it needs to make hemoglobin, the protein that carries oxygen in red blood cells.
• Tiredness, shortness of breath, dizziness, cold hands and feet and pale skin are the typical signs, and mild cases may have none.
• The cause matters: heavy periods, pregnancy and bleeding in the digestive tract are among the common ones.
• A blood test starts the work-up, and your provider may add iron tests or a ferritin test.
• Iron supplements should be taken only when a provider recommends them, and treatment usually lasts months.

What iron deficiency feels like

MedlinePlus says anemia means your blood does not carry enough oxygen to the body, and it can cause tiredness, feeling cold, dizziness and irritability. The NHS lists the common signs of iron deficiency anemia as tiredness and low energy, shortness of breath, heart palpitations, paler skin and headaches.

• Less common signs listed by the NHS: ringing in the ears, a strange taste, itching, a sore tongue, hair loss, craving non-food items such as ice or paper, difficulty swallowing, mouth ulcers at the corners of the mouth, spoon-shaped nails and restless legs syndrome.
• NHLBI notes that mild or moderate cases may have no symptoms, and that chest pain or shortness of breath can signal more serious disease.

Why iron runs low

The WHO calls iron deficiency, usually from not getting enough iron in the diet, the most common nutritional cause of anemia, and says anemia is a symptom of an underlying condition, not a disease on its own. It is most common in children under five, in menstruating girls and women, and in pregnant and postpartum women.

• Blood loss: heavy periods, childbirth, and bleeding in the stomach or intestines from ulcers, inflammation of the bowel, piles, or regular use of aspirin or anti-inflammatory painkillers such as ibuprofen. The NHS adds that bowel or stomach cancers are a less common cause, which is why an unexplained case is investigated.
• Poor absorption: NHLBI lists celiac disease, Crohn's disease, ulcerative colitis, Helicobacter pylori infection, and stomach or intestinal surgery, including weight loss surgery.
• Not enough iron in food, such as during pregnancy or when a young child moves to solid foods.
• Other conditions: NHLBI mentions kidney disease and long-lasting inflammatory conditions.

Which tests to discuss

MedlinePlus explains that a provider diagnoses anemia with a physical exam and blood tests. The tests it lists include the complete blood count, iron tests and the ferritin blood test, and NHLBI describes a blood test that checks the complete blood count, hemoglobin, blood iron and ferritin.

The NHS says a full blood count needs no preparation. If the cause remains unclear, your provider may order a stool test that detects blood, or refer you to a specialist. This guide does not interpret your own results: ask your provider what each number means for you, since ranges depend on age, sex and pregnancy, as WHO notes.

Food: what helps and what gets in the way

The WHO suggests iron-rich foods, namely lean red meat, fish, poultry, legumes, fortified cereals and dark leafy greens, eaten with vitamin C-rich foods to help absorption. Tea, coffee, cocoa, bran and calcium around iron-rich meals slow absorption.

The NHS adds dried fruit such as apricots, prunes and raisins, and pulses to the list, and says that milk and dairy foods and wholegrain cereals, which are high in phytic acid, also reduce iron absorption. A dietitian referral may help if eating iron-rich foods is difficult.

Food alone does not always correct a deficit that is already established. NHLBI names oral iron supplements as the most common treatment, so diet is usually a support, not the whole plan.

Iron supplements: why a provider should guide them

The WHO says to take iron supplements only if a qualified health care provider recommends them, and to take calcium and iron supplements at different times of day because calcium reduces iron absorption.

• Duration: the NHS says iron tablets are usually taken for about six months, and NHLBI says restoring iron often takes three to six months. Repeat blood tests may be done over the following months to check recovery.
• Side effects: constipation or diarrhea, stomach pain, heartburn, nausea and darker stools. The NHS suggests taking them with or soon after food to reduce side effects, and says taking them with orange juice may improve absorption.
• Alternatives: NHLBI lists iron given through a vein for serious cases or long-term conditions, and treating the underlying cause, such as a bleeding ulcer or heavy periods.
• Safety: keep iron tablets away from children, as the NHS warns that an overdose can be fatal.

When to see a doctor

Make a routine appointment if you notice the signs above, if your periods are heavy, or if you are pregnant or planning a pregnancy. The NHS notes that untreated iron deficiency anemia weakens the immune system and can lead to heart or lung complications and greater risks in pregnancy.

Red flags: call 911 for chest pain, severe breathlessness or fainting. Get urgent care if you see blood in your stool or have black, tarry stools, as these can be signs of bleeding in the digestive tract.

Questions to bring:

• Why is my iron low, and do I need more tests to find out?
• Should I take iron, and for how long?
• Could my medicines, such as aspirin or ibuprofen, be involved?
• When should I have my blood rechecked?

Questions and answers

Sources

1. World Health Organization — Anaemia
2. NHS — Iron deficiency anaemia
3. MedlinePlus — Anemia
4. NHLBI — Iron-deficiency anemia

Sources checked on 29 October 2026.