Iron Deficiency Anaemia: The Complete Guide to Symptoms, Causes and Treatment

Iron deficiency is the most common nutritional deficiency in the world. The World Health Organization estimates that anaemia affects around 40 percent of children under five, around 37 percent of pregnant women and around 30 percent of women of reproductive age worldwide, and iron deficiency is the leading cause. Iron deficiency anaemia makes people tired, breathless and less able to work, learn and enjoy life. In pregnancy it increases the risk of premature birth and low birth weight, and in young children it can affect brain development.

Iron deficiency is also a clue. In adults, especially men and women after menopause, it can be the first sign of hidden bleeding from the gut, including bowel cancer. This complete guide explains what iron does, the symptoms of iron deficiency, the many causes, how it is diagnosed, how to eat for iron, how to take iron tablets so they work and cause fewer side effects, when intravenous iron is needed, and how iron deficiency affects pregnancy, children, athletes and older adults.

What does iron do?

Iron is an essential mineral. Its most important job is helping to make haemoglobin, the protein in red blood cells that carries oxygen from the lungs to every part of the body. Iron is also needed for muscle function (in a protein called myoglobin), energy production in cells, a healthy immune system, brain development and function, and healthy skin, hair and nails.

The body cannot make iron, so it must come from food. The body carefully controls how much iron it absorbs from the gut, because it has no active way to get rid of excess iron. Iron is stored mainly in the liver, bone marrow and spleen, in a protein called ferritin.

Iron deficiency and anaemia: what is the difference?

Iron deficiency develops in stages:

1. Iron depletion: iron stores (ferritin) fall, but haemoglobin is still normal.
2. Iron deficiency without anaemia: stores are empty and the body begins to struggle to make red blood cells, but haemoglobin is still within the normal range. People may already have symptoms such as fatigue, poor concentration and hair loss.
3. Iron deficiency anaemia: haemoglobin falls below normal. Red blood cells become smaller and paler than usual.

Anaemia means having less haemoglobin than normal. It has many causes, including vitamin B12 and folate deficiency, chronic disease, kidney disease, inherited conditions such as sickle cell disease and thalassaemia, malaria and other infections, and bone marrow problems. Iron deficiency is the most common cause worldwide.

Symptoms of iron deficiency

Symptoms often develop gradually, and many people adapt without realising how unwell they are:

• Tiredness and lack of energy.
• Shortness of breath, especially on exertion.
• Fast or pounding heartbeat (palpitations).
• Pale skin, pale inner eyelids and pale nail beds.
• Headaches.
• Dizziness or light-headedness.
• Cold hands and feet.
• Difficulty concentrating and poor memory.
• Hair loss.
• Brittle, spoon-shaped nails (koilonychia).
• Sore tongue, cracks at the corners of the mouth.
• Difficulty swallowing in rare cases.
• Restless legs, particularly at night.
• Pica: craving and eating non-food items such as ice (pagophagia), clay, soil, chalk or starch.
• Reduced exercise performance.
• Low mood and irritability.
• More frequent infections.

People with heart disease may notice worsening chest pain or breathlessness. In children, iron deficiency can cause poor appetite, slow growth, irritability and difficulties with learning and behaviour.

Seek urgent medical care if you have severe breathlessness, chest pain, fainting, or signs of significant bleeding such as vomiting blood, passing black or bloody stools, or very heavy bleeding.

What causes iron deficiency?

Iron deficiency happens when the body’s iron needs are greater than the iron absorbed from food. There are three broad causes: blood loss, increased need, and not enough iron absorbed.

Blood loss

• Heavy menstrual bleeding: the most common cause in women of reproductive age. Many women do not realise their periods are heavy. Signs include needing to change pads or tampons every one to two hours, passing large clots, bleeding through to clothes or bedding, periods lasting more than seven days, or needing double protection.
• Bleeding from the gut: from stomach ulcers, inflammation, haemorrhoids, polyps, bowel cancer or stomach cancer. Bleeding can be slow and invisible. This is the most important cause to rule out in men and in women after menopause.
• Medicines: aspirin, anti-inflammatory painkillers and blood thinners increase the risk of gut bleeding.
• Parasitic infections: hookworm infection is a major cause of iron deficiency in tropical and subtropical regions. Schistosomiasis can cause blood loss in urine or stool.
• Frequent blood donation, nosebleeds, or blood loss in the urine.
• Childbirth, particularly with heavy bleeding.

Increased need

• Pregnancy: iron needs rise sharply to support the baby, placenta and increased blood volume.
• Infancy, childhood and adolescence: rapid growth increases needs.
• Endurance athletes: may have higher losses and needs.

Not enough iron absorbed

• Low dietary intake: diets low in iron-rich foods, particularly where meat, fish and poultry are scarce or unaffordable, or poorly planned vegetarian and vegan diets.
• Coeliac disease: damage to the small intestine reduces iron absorption. It is a common hidden cause of iron deficiency and should be tested for.
• Helicobacter pylori infection of the stomach.
• Inflammatory bowel disease such as Crohn’s disease.
• Weight-loss surgery and other stomach or bowel surgery.
• Long-term use of acid-reducing medicines, which can reduce iron absorption.
• Atrophic gastritis.
• Chronic kidney disease and heart failure, where inflammation affects iron handling.

How iron deficiency is diagnosed

Blood tests

• Full blood count: measures haemoglobin and the size of red blood cells. Iron deficiency typically causes low haemoglobin with small (microcytic) and pale (hypochromic) red cells.
• Serum ferritin: the best single test of iron stores. A low ferritin confirms iron deficiency. Thresholds vary: the World Health Organization uses below 15 micrograms per litre for adults, but many experts and guidelines now consider levels below 30 micrograms per litre to indicate iron deficiency, particularly in people with symptoms.
• Important caveat: ferritin also rises with inflammation, infection, liver disease and cancer. In these situations, ferritin can appear normal or high even when iron stores are low. Other tests help in this case.
• Transferrin saturation: shows how much iron is available for making red blood cells. Low levels (below about 20 percent) suggest iron deficiency, even when ferritin is normal.
• Other tests: C-reactive protein (to check for inflammation), vitamin B12 and folate, kidney function, and sometimes reticulocyte haemoglobin.

Finding the cause

Finding out why iron is low is as important as treating it. Depending on age, sex and symptoms, investigations may include:

• A coeliac disease blood test.
• A stool test for hidden blood or a faecal immunochemical test (FIT).
• Testing for Helicobacter pylori.
• Stool tests for parasites, in areas where hookworm and other infections are common.
• Urine tests for blood.
• Endoscopy and colonoscopy: cameras to examine the stomach and bowel. These are recommended for men and postmenopausal women with iron deficiency anaemia without a clear cause, because of the risk of cancer. Many countries have fast-track pathways for this.
• Assessment of menstrual bleeding and, if heavy, gynaecological evaluation.

In young women with heavy periods and no other symptoms, extensive investigation is often not needed, but coeliac testing is still recommended. Any warning signs, such as weight loss, a change in bowel habit, blood in stools, abdominal pain or a family history of bowel cancer, should prompt further tests.

Eating for iron

There are two types of dietary iron:

• Haem iron: found in animal foods such as red meat, liver, poultry and fish. It is absorbed well, around 15 to 35 percent.
• Non-haem iron: found in plant foods and in fortified foods. It is absorbed less well, around 2 to 20 percent, depending on what it is eaten with.

Iron-rich foods

• Red meat such as beef, lamb and goat.
• Liver and other organ meats (not recommended in large amounts during pregnancy because of high vitamin A content).
• Chicken and turkey, especially dark meat.
• Fish and shellfish, including sardines, tuna, mussels, clams and oysters.
• Eggs.
• Beans, lentils, chickpeas and peas.
• Tofu and tempeh.
• Dark green leafy vegetables such as spinach, kale, amaranth leaves, pumpkin leaves and moringa.
• Nuts and seeds, such as pumpkin seeds, sesame seeds and cashews.
• Dried fruit such as apricots, raisins, prunes and dates.
• Wholegrains such as millet, teff, sorghum, quinoa and oats.
• Iron-fortified breakfast cereals, breads and flours.

Boosting absorption

• Combine iron-rich foods with vitamin C: citrus fruits, guava, mango, pineapple, tomatoes, peppers, kiwi and broccoli can greatly increase absorption of plant iron.
• Combine plant iron with some animal foods, even small amounts of meat, fish or poultry, which increases non-haem iron absorption.
• Avoid tea and coffee with meals: the tannins and polyphenols in tea and coffee can reduce iron absorption significantly. Drink them at least an hour before or after meals.
• Calcium from dairy and supplements can reduce iron absorption when taken at the same meal.
• Soaking, sprouting and fermenting grains and legumes reduces phytates, which bind iron.

Diet alone is usually enough to prevent iron deficiency in many people, but once iron deficiency anaemia has developed, diet alone is rarely enough to correct it. Supplements are usually needed.

Iron tablets: how to take them properly

Oral iron supplements are the first-line treatment for most people. Common forms include ferrous sulphate, ferrous fumarate and ferrous gluconate. They contain different amounts of “elemental iron”, which is what matters for treatment.

New evidence on dosing

For many years, people were told to take iron two or three times a day. Research has shown that a single dose of iron raises a hormone called hepcidin for about 24 hours, which blocks further iron absorption. As a result:

• Taking iron once a day is as effective as taking it several times a day, with fewer side effects.
• Taking iron on alternate days may lead to even better absorption per dose and fewer side effects, and is now recommended by some experts and guidelines, particularly for people who struggle with side effects.

Your healthcare provider will advise on the best regimen for you.

Tips for taking iron

• Take iron on an empty stomach, ideally in the morning, for best absorption. If it upsets your stomach, take it with a small amount of food.
• Take it with water or orange juice (vitamin C), not with tea, coffee or milk.
• Keep at least two hours between iron and antacids, calcium supplements, some antibiotics (such as tetracyclines and quinolones) and levothyroxine (leave four hours).
• Continue treatment for around three months after haemoglobin returns to normal, to refill iron stores.
• Keep iron tablets out of the reach of children. Iron overdose is a leading cause of poisoning deaths in young children and is a medical emergency.

Side effects

Common side effects include nausea, stomach pain, constipation, diarrhoea and dark or black stools. Black stools from iron are harmless, but stools that are black, sticky and tar-like with a bad smell, especially with dizziness, can be a sign of bleeding and need urgent assessment. To reduce side effects, try taking iron with food, switching to alternate days, using a lower dose or a different preparation, or treating constipation with fluids, fibre and a gentle laxative.

Monitoring

Haemoglobin usually starts to rise within two to four weeks, rising by around 10 to 20 grams per litre every two to three weeks. A blood test after two to four weeks shows whether treatment is working. If haemoglobin does not rise, the reasons may include not taking the tablets, ongoing blood loss, poor absorption (for example, coeliac disease), or another cause of anaemia.

Intravenous (IV) iron

Iron can be given directly into a vein as an infusion. Modern IV iron preparations, such as ferric carboxymaltose, ferric derisomaltose and iron sucrose, are effective and generally safe. IV iron may be used when:

• Oral iron is not tolerated or does not work.
• Iron absorption is impaired, for example in inflammatory bowel disease, coeliac disease or after weight-loss surgery.
• Rapid replacement is needed, for example in late pregnancy, before surgery, or with ongoing blood loss.
• People have chronic kidney disease or heart failure.

Serious allergic reactions are rare, and infusions are given in settings where staff are trained to manage them. Some IV iron preparations can cause low phosphate levels with repeated use. Skin staining at the injection site can occur if iron leaks out of the vein, so report any discomfort during the infusion.

Blood transfusion

Blood transfusion is reserved for severe anaemia with symptoms, active major bleeding, or when rapid correction is essential and other options are not suitable. It is not a substitute for finding and treating the cause.

Iron deficiency in pregnancy

Pregnancy increases iron needs significantly, particularly in the second and third trimesters. Iron deficiency anaemia in pregnancy is linked to premature birth, low birth weight, increased risk of needing a blood transfusion after birth, and maternal fatigue and postnatal depression. Babies born to mothers with iron deficiency may have lower iron stores.

• The World Health Organization recommends daily iron and folic acid supplements for pregnant women in many settings, particularly where anaemia is common. Recommendations vary between countries.
• Haemoglobin is checked at the first antenatal visit and again later in pregnancy. Ferritin may also be checked.
• Iron-rich foods and good absorption habits are important, but supplements are often needed.
• IV iron may be used in the second and third trimesters if oral iron does not work or anaemia is severe.
• Delayed cord clamping at birth, where the umbilical cord is not clamped for at least one minute, increases the baby’s iron stores.

See also our guide to anaemia in pregnancy.

Iron deficiency in babies and children

Babies are born with iron stores that last about four to six months. After that, iron must come from the diet. Iron deficiency in infancy and early childhood is linked to delays in development, learning and behaviour, which may not fully reverse.

• Breast milk contains small amounts of well-absorbed iron. From around six months, iron-rich complementary foods are essential: pureed meat, fish, eggs, legumes and iron-fortified cereals.
• Avoid giving cow’s milk as the main drink before 12 months of age, and limit it to recommended amounts in toddlers. Too much milk fills children up, displaces iron-rich foods and can cause gut irritation.
• Premature and low birth weight babies often need iron supplements.
• Deworming programmes in areas with high rates of intestinal worms help reduce anaemia in children.
• Children with iron deficiency are treated with iron drops or syrup at a dose based on weight. Iron supplements in malaria-endemic areas should be given alongside malaria prevention and treatment, following local guidelines.

Iron deficiency in teenagers and young women

Teenage girls are at high risk because of rapid growth, the start of periods, and sometimes restrictive diets. Iron deficiency in adolescence can affect school performance, mood, energy and sporting performance. Heavy periods in teenagers should not be dismissed as normal; they can sometimes be a sign of an inherited bleeding disorder, such as von Willebrand disease.

Athletes and iron

Endurance athletes, especially female runners, are at increased risk of iron deficiency because of sweat losses, minor gut bleeding during exercise, red blood cell breakdown from foot strike, increased demand, and the effect of exercise-induced inflammation on hepcidin. Symptoms include declining performance, unusual fatigue and slower recovery. Athletes should not take iron supplements without testing, because excess iron can be harmful.

Iron deficiency in older adults

In older adults, iron deficiency is often caused by bleeding from the gut, chronic disease, medicines such as aspirin and anticoagulants, poor diet and reduced absorption. It can worsen heart failure, increase falls risk and contribute to frailty and confusion. Iron deficiency anaemia in an older adult almost always needs investigation to look for gut causes, including cancer.

Iron deficiency with heart failure and kidney disease

Iron deficiency, with or without anaemia, is common in people with heart failure and chronic kidney disease. In heart failure, intravenous iron has been shown to improve symptoms, exercise capacity and quality of life, and to reduce hospital admissions. In kidney disease, iron is often given alongside medicines that stimulate red blood cell production.

Too much iron: why you should not self-treat

Iron supplements are widely available, but taking them without a confirmed deficiency can be harmful. Excess iron can damage the liver, heart and pancreas. Hereditary haemochromatosis, a common genetic condition in people of Northern European descent, causes the body to absorb too much iron. Taking iron supplements can worsen it. Always confirm iron deficiency with a blood test before taking supplements long term, unless you are pregnant or advised by a healthcare provider as part of a public health programme.

A note for nurses and healthcare workers

Nurses are central to identifying and treating iron deficiency: noticing pallor and fatigue, asking about heavy periods, checking haemoglobin in pregnancy, teaching patients how to take iron tablets effectively, managing IV iron infusions and monitoring for reactions, and making sure the cause has been investigated. Nurses working night shifts, those with heavy periods and those following plant-based diets may themselves be at risk. If you are always exhausted, consider asking for a blood test rather than assuming it is just the job.

Common myths about iron deficiency

• “Spinach is the best source of iron.” Spinach contains iron, but it is poorly absorbed because of oxalates. Meat, fish, legumes and fortified foods are often better sources.
• “Feeling tired is normal for busy women.” Persistent fatigue deserves investigation; iron deficiency is common and treatable.
• “Heavy periods are just something to put up with.” Heavy menstrual bleeding is a medical condition that can be treated.
• “More iron is better.” Excess iron can be harmful. Take iron only when needed and at the right dose.
• “If my haemoglobin is normal, my iron is fine.” Iron stores can be low before anaemia develops.

Heavy periods: the hidden epidemic behind iron deficiency

Heavy menstrual bleeding affects around one in four to one in three women at some point, yet many never seek help because they assume their periods are normal or feel embarrassed to talk about them. Heavy bleeding is defined not by a measured amount, but by its impact: bleeding that interferes with physical, social, emotional or work life. Signs include soaking through a pad or tampon every one to two hours, needing to get up at night to change protection, passing clots larger than a coin, flooding through clothes, avoiding activities during periods, and periods lasting more than seven days.

Causes include fibroids, polyps, adenomyosis, hormonal changes around the teenage years and perimenopause, polycystic ovary syndrome, thyroid problems, bleeding disorders such as von Willebrand disease, copper intrauterine devices and some medicines, including blood thinners. Many women have no identifiable cause.

Effective treatments are available, including the hormonal intrauterine system (a small device in the womb that releases a progestogen), tranexamic acid tablets taken during periods, anti-inflammatory painkillers, hormonal contraceptives, and procedures for fibroids or polyps. Treating heavy periods is often essential to prevent iron deficiency from coming back. If your periods are heavy, talk to a nurse or healthcare provider; you do not need to put up with it.

Iron deficiency without anaemia: does it matter?

For years, attention focused on anaemia, and iron deficiency without anaemia was often overlooked. Research now shows that low iron stores, even with normal haemoglobin, can cause fatigue, poor concentration, reduced exercise capacity, restless legs and hair loss. Treating iron deficiency without anaemia in people with symptoms and low ferritin, particularly women with heavy periods, has been shown in some studies to improve fatigue. It also prevents progression to anaemia. If you have symptoms and your haemoglobin is normal, ask whether your ferritin has been checked.

Restless legs and iron

Restless legs syndrome causes an uncomfortable urge to move the legs, usually in the evening or at night, relieved by moving. It disrupts sleep and is closely linked to iron levels in the brain. People with restless legs are often advised to have their ferritin checked, and iron supplements may help when ferritin is below around 75 micrograms per litre, a higher threshold than used for anaemia. Restless legs is also common in pregnancy, partly because of iron deficiency.

Anaemia around the world

Anaemia is one of the world’s most widespread health problems. The highest rates are in South Asia, West and Central Africa, and parts of the Middle East, where poverty, limited access to iron-rich foods, malaria, intestinal worms, frequent pregnancies, and inherited blood disorders all contribute. The World Health Assembly set a global target to halve anaemia in women of reproductive age, but progress has been slow, and many countries are off track. Effective public health measures include fortifying staple foods such as flour, rice and salt with iron and other micronutrients, iron and folic acid supplementation programmes in pregnancy, delayed cord clamping, deworming, malaria prevention, family planning that allows women time to recover between pregnancies, and improving overall nutrition. Nurses, midwives and community health workers deliver most of these interventions.

Other causes of anaemia to consider

Not all anaemia is due to iron deficiency, and giving iron to someone who does not need it can delay the right diagnosis. Other common causes include:

• Vitamin B12 deficiency: caused by pernicious anaemia (an autoimmune condition), strict vegan diets without supplements, some stomach surgery and long-term metformin or acid-reducing medicines. It can cause nerve damage if not treated.
• Folate deficiency: from poor diet, pregnancy, alcohol excess and some medicines.
• Anaemia of chronic disease: linked to long-term infections, inflammation, kidney disease and cancer.
• Thalassaemia trait: an inherited condition, common in people of Mediterranean, Middle Eastern, South Asian, Southeast Asian and African descent, which causes small red cells similar to iron deficiency but normal or high ferritin. Iron does not help and should not be given unless iron deficiency is also present.
• Sickle cell disease and other inherited blood conditions.
• Malaria and other infections that destroy red cells.
• Bone marrow conditions, which are less common but important to rule out when anaemia is unexplained.

A sample iron-friendly day

• Breakfast: iron-fortified cereal or porridge with seeds, plus an orange or a glass of orange juice. Drink tea or coffee later in the morning instead of with breakfast.
• Lunch: a bean, lentil or chickpea stew with tomatoes and peppers, served with wholegrain bread, rice or millet, and a side of dark leafy greens.
• Snack: a handful of pumpkin seeds and dried apricots, or a hard-boiled egg.
• Dinner: lean red meat, chicken or fish with vegetables and a starchy staple, or tofu stir-fried with broccoli and peppers.

Plan meals so that iron-rich foods are combined with vitamin C-rich fruit or vegetables, and keep tea and coffee for between meals.

Questions to ask your healthcare provider

• What are my haemoglobin and ferritin levels, and what do they mean?
• What is causing my iron deficiency, and does it need further investigation?
• Should I be tested for coeliac disease or Helicobacter pylori?
• Which iron supplement should I take, how often, and for how long?
• When will my blood be rechecked?
• What should I do if I cannot tolerate the tablets?
• Would IV iron be suitable for me?
• Can my heavy periods be treated?

Iron, the brain and mental health

Iron is essential for the brain. It is needed to produce neurotransmitters such as dopamine and serotonin, to build the protective coating around nerves, and to supply brain cells with energy. In babies and young children, iron deficiency during periods of rapid brain growth can affect attention, memory, language and motor development, and some of these effects may persist even after iron is corrected. This is why preventing iron deficiency in pregnancy and early childhood is a global priority.

In adults, iron deficiency is linked to poor concentration, low mood, irritability, anxiety and reduced ability to cope with stress. Some studies suggest that people with iron deficiency anaemia have a higher risk of depression and anxiety. Treating iron deficiency often improves energy and mood, though persistent mental health symptoms should be assessed in their own right.

Iron and surgery

Anaemia before major surgery increases the risk of complications, the need for blood transfusion, longer hospital stays and slower recovery. Many hospitals now follow “patient blood management” programmes, which check for anaemia several weeks before planned surgery and treat iron deficiency with tablets or IV iron beforehand. If you are due to have a major operation, ask whether your blood count and iron levels have been checked. After surgery or childbirth with significant blood loss, iron replacement helps recovery and reduces fatigue.

Iron deficiency after weight-loss surgery

People who have had bariatric surgery, especially gastric bypass, are at high risk of iron deficiency because the parts of the gut that absorb iron are bypassed and stomach acid is reduced. Lifelong monitoring of iron, vitamin B12, folate, vitamin D and calcium is recommended, along with daily multivitamin and mineral supplements. Many people need additional iron, and some require IV iron because oral iron is poorly absorbed. Menstruating women who have had weight-loss surgery are at particularly high risk.

Iron and plant-based diets

Vegetarian and vegan diets can provide enough iron, but they require more planning because plant iron is less well absorbed. Studies show that people following plant-based diets often have lower iron stores, although not always higher rates of anaemia. Practical steps include eating legumes daily, choosing iron-fortified cereals and breads, including tofu and tempeh, snacking on seeds and nuts, adding vitamin C-rich foods to every meal, cooking in cast-iron pots (which can add small amounts of iron to food), and keeping tea and coffee away from mealtimes. Vegans should also take a vitamin B12 supplement, because B12 is found almost only in animal foods and deficiency also causes anaemia. Women with heavy periods following plant-based diets may benefit from having their ferritin checked periodically.

Recovering your energy

Once treatment starts, many people notice improvements in energy, breathlessness and concentration within a few weeks, even before haemoglobin is fully back to normal. Hair loss and nail changes take longer to recover, often several months, because hair and nails grow slowly. Be patient, keep taking your iron as advised, and complete the full course to rebuild your stores. Most importantly, make sure the cause has been addressed so that you do not end up back where you started.

Iron deficiency and blood donation

Regular blood donors, particularly women and frequent donors, can become iron deficient because each donation removes a significant amount of iron. Many blood services now check haemoglobin before every donation and some measure ferritin, recommend longer intervals between donations, or advise iron supplements for frequent donors. If you donate blood and feel unusually tired, or have been deferred because of low haemoglobin, talk to the blood service or your healthcare provider about your iron levels.

Key points to remember

• Iron deficiency is common, especially in women, children and pregnancy, and it is treatable.
• Low ferritin confirms iron deficiency, but inflammation can hide it.
• Always look for the cause, particularly in men and women after menopause.
• Take iron once daily or on alternate days, on an empty stomach, away from tea, coffee and calcium.
• Continue iron for about three months after your blood count recovers.

Frequently asked questions

How long does it take to correct iron deficiency anaemia?

Haemoglobin usually improves within a few weeks and normalises in two to three months. Iron tablets should then be continued for about three more months to refill stores.

Can iron deficiency cause hair loss?

Yes. Iron deficiency is a common, reversible cause of hair shedding, particularly in women.

Why are my stools black on iron tablets?

Iron commonly turns stools dark green or black. This is harmless. Black, sticky, tar-like stools with dizziness may indicate bleeding and need urgent assessment.

Is IV iron better than tablets?

IV iron works faster and avoids gut side effects, but tablets are effective for most people. IV iron is used when tablets are not suitable or rapid replacement is needed.

Can vegetarians and vegans get enough iron?

Yes, with careful planning: include legumes, tofu, wholegrains, seeds, leafy greens and fortified foods, combine them with vitamin C, and avoid tea and coffee at meals.

Should I take iron with vitamin C tablets?

Vitamin C from food or a glass of orange juice is usually enough to help absorption. Separate vitamin C tablets are not routinely needed.

But what if my iron keeps dropping even on treatment?

If your iron or haemoglobin falls again after treatment, or does not improve despite taking tablets properly, it usually means the underlying cause has not been found or fixed. Common reasons include ongoing heavy periods, undiagnosed coeliac disease, bleeding from the gut, Helicobacter pylori infection, or poor absorption. Ask your healthcare provider whether the cause has been fully investigated, whether you need referral for heavy periods or a camera test, and whether IV iron would be appropriate. Treating iron deficiency without finding the cause is like bailing water out of a boat without fixing the leak.

Related: Anaemia symptoms and iron-rich foods · Anaemia in pregnancy · Healthy pregnancy: the complete guide

Sources: World Health Organization (anaemia fact sheet, guideline on haemoglobin cut-offs and ferritin thresholds, iron supplementation recommendations), British Society of Gastroenterology guidelines for iron deficiency anaemia in adults, International Federation of Gynecology and Obstetrics (FIGO), Moretti and Stoffel studies on hepcidin and iron dosing, European Society of Cardiology heart failure guidelines, Global Burden of Disease Study.