Iron deficiency and anemia

At a glance

  • We need iron in our diet to stay healthy.
  • People who eat a good mix of different foods normally get enough iron.
  • Iron deficiency may be a result of things like heavy periods, an imbalanced diet, pregnancy and certain diseases.
  • Possible symptoms include pale skin, tiredness or exhaustion.
  • Iron deficiency can lead to anemia over time (a lack of healthy red blood cells).
  • It can be treated with iron supplements, for example.


Photo of an exhausted woman with pale skin

Iron is a trace element. You need it in your diet to stay healthy. Adults have about 3 to 5 grams of iron in their body, most of it in their red blood cells. Our bodies need iron for a number of reasons, including to make hemoglobin. Hemoglobin is found in red blood cells (erythrocytes) and helps to transport oxygen to all of our cells and organs. It also plays an important role in energy production and cell division.

We absorb iron from the food we eat. People who eat a good mix of different foods usually get enough iron in their diet. Those who don’t get enough iron develop an iron deficiency. That can happen if our bodies need especially high amounts of iron, such as during pregnancy in women or growth spurts in children. Blood loss and various diseases can also result in iron deficiency.

Iron deficiency can cause anemia over time (a lack of healthy red blood cells). But it can be treated effectively with iron supplements. It is also important to tackle the cause of the deficiency if possible.


Mild iron deficiency usually goes unnoticed. A more severe deficiency can cause various symptoms, including:

  • Pale skin
  • Tiredness
  • Unusual exhaustion after physical activity
  • Difficulty concentrating and forgetfulness
  • Restlessness
  • Headaches
  • Cracked skin in the corners of the mouth
  • Recurring sores on the lining of the mouth (mouth ulcers)
  • Brittle nails
  • Hair loss
  • Shortness of breath
  • Restless legs syndrome
  • Difficulty swallowing

Some affected people also have a strong urge to chew on ice cubes or crushed ice (pagophagia).


The most common causes of iron deficiency are:

  • Blood loss – for example, due to (often unnoticed) bleeding in the digestive tract because of ulcers, tumors or . Other possible causes of blood loss include heavy periods, blood donations and injuries.
  • Low iron intake – perhaps due to a very one-sided diet or eating disorders such as anorexia. People who are on a vegetarian or vegan diet may find it harder to get enough iron too.
  • Increased iron needs – especially during pregnancy and when breastfeeding, during growth spurts in children and teenagers, or due to competitive sports.
  • Reduced iron absorption – for instance, due to celiac disease, chronic inflammatory bowel diseases, gastritis, or after the surgical removal of parts of the stomach. Some medications can also reduce the absorption of iron, including antacids for the stomach and painkillers such as acetylsalicylic acid (the drug in medicines like Aspirin) and ibuprofen. Babies and toddlers who drink a lot of cow’s milk may absorb less iron too.
  • Poor iron processing – where enough iron is actually absorbed but the body can’t use it properly. This ‘functional’ iron deficiency may be caused by things like cancer or kidney failure.

Iron deficiency is common in people with heart failure too. It only rarely has genetic causes.


Iron deficiency is the most common type of deficiency worldwide. About 5 to 10% of all adults in Europe are affected. It is more common in women before the menopause, mainly because of blood loss during their monthly period. Children are also more often affected because they need more iron during growth spurts.

It is estimated that about 2 to 5% of people in Europe have anemia due to iron deficiency.


Iron deficiency sometimes goes away again quickly: After giving blood or an injury, the body usually soon makes new red blood cells and refills its iron reserves with iron from food.

But iron deficiency can last for longer or keep coming back, for example due to heavy periods. If the body loses blood too often, it might no longer be able to completely replace it.

There are three stages of iron deficiency:

  • Stage 1: The body doesn’t get enough iron. To continue making enough hemoglobin, it uses stored iron instead (for example, from the liver or spleen). Iron reserves go down but there are usually no symptoms.
  • Stage 2: Iron reserves are empty. There is still enough hemoglobin in the blood to transport oxygen to the cells. But the body can’t make any more hemoglobin. That also affects the production of new red blood cells. Symptoms may occur.
  • Stage 3: Anemia develops because the body has so little hemoglobin. Cells and organs are no longer supplied with enough oxygen. Symptoms are common. This is known as iron-deficiency anemia.


Mild or short-term iron deficiency usually doesn't cause any problems. If the body doesn’t get enough iron for a long time, though, longer-lasting anemia may develop. Then the blood can no longer supply the cells and organs with enough oxygen, and they can't function properly. Various problems develop, sometimes even including organ damage or heart failure. And you're more likely to get infections.

If pregnant women have iron-deficiency anemia, it increases the risk of complications such as premature birth or an underweight newborn baby. Because of this, pregnant women’s iron levels are checked regularly.

Severe, long-term iron deficiency in young children can lead to developmental disorders.


Doctors diagnose iron deficiency with a blood test. A number of different things are measured in the blood and then looked at together. This includes

  • how full the body’s iron reserves are (ferritin and transferrin),
  • how big the red blood cells are (MCV level) and how much hemoglobin they contain (MCH level), and
  • the total amount of hemoglobin in the blood.

If iron deficiency or anemia is diagnosed, your doctor will first ask about possible causes and do a physical examination. Further examinations will follow if necessary, such as a stool ("poop") sample, gastroscopy or colonoscopy to check for bleeding. It can be a good idea for women to see their gynecologist, for instance if they have heavy monthly periods.


It is normally possible to get enough iron by eating a balanced diet. Iron-rich foods include things like meat, spinach, lentils, chickpeas, tuna, oats and cashew nuts. Vitamin C helps your body to absorb iron.

There is usually no benefit to taking iron supplements for prevention. In fact, too much iron can be harmful. So it's important to speak to your doctor before taking iron supplements.


If possible, the cause of iron deficiency is treated. That may include things like treating diseases of the digestive tract that cause bleeding. There are also treatment options for heavy periods.

Mild iron deficiency (stage 1) doesn't usually cause any problems and isn’t normally treated with medication. Depending on the situation, it can be a good idea to try to get more iron in your diet.

More severe iron deficiency (stage 2) or anemia (stage 3) can be treated with iron supplements – in the form of tablets or drops, for example. When treating anemia, people are advised to take the iron supplements for at least a further three months after their blood iron levels have gone back to normal. That then also fills their body’s iron reserves. Infusions (drips) are sometimes an option as well. It is important to make sure you get enough iron in your diet. Professional dietary advice can help here.

Iron supplements may have side effects such as stomach ache, constipation and nausea. Very high doses can also damage organs. It is important to keep iron supplements out of the reach of children because an overdose can be especially dangerous for them.

Further information

When people are ill or need medical advice, they usually go to see their family doctor or pediatrician first. Specialists can be consulted too, including gynecologists, cardiologists and nephrologists (kidney specialists).

You can read about how to find the right doctor in our topic "Health care in Germany" – and our list of questions can help you to prepare for your appointment.

Deutsche Gesellschaft für Hämatologie und Medizinische Onkologie (DGHO). Eisenmangel und Eisenmangelanämie (Leitlinie). 2022.

Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH). Eisenmangelanämie (S1-Leitlinie). AWMF-Registernr.: 025-021. 2021.

Ko CW, Siddique SM, Patel A et al. AGA Clinical Practice Guidelines on the Gastrointestinal Evaluation of Iron Deficiency Anemia. Gastroenterology 2020; 159(3): 1085-1094.

Pschyrembel Online. 2023.

Snook J, Bhala N, Beales ILP et al. British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults. Gut 2021; 70(11): 2030-2051.

World Health Organization (WHO). WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. Geneva: WHO; 2020.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Created on September 18, 2023

Next planned update: 2026


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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