Last Updated: 20 October 2026
iron deficiency symptoms are easy to brush aside in autumn, when shorter days, darker evenings and the first colds of the season give everyone a ready excuse for feeling tired. Yet iron deficiency is one of the most common nutritional problems in the UK, and when the body cannot make enough healthy red blood cells, the tiredness is different in kind: it lingers after rest, it affects concentration and stamina, and it often arrives alongside breathlessness, a racing heartbeat or unusually pale skin that friends and family may notice before you do.
This guide explains the main signs to watch for, from the everyday symptoms almost everyone notices first to the less familiar ones that can appear in your hair, nails, tongue and legs. It covers the usual causes, including heavy periods, pregnancy and hidden blood loss from the stomach or bowel, how a GP tests for low iron, and what treatment involves, from iron tablets and iron-rich foods to the practical details that help tablets work better. It is general information only and is not medical advice — if you are worried about iron deficiency symptoms or your own health, speak to your GP, a pharmacist or NHS 111.
What are iron deficiency symptoms? Iron deficiency symptoms most often include tiredness and a lack of energy, shortness of breath, a noticeable heartbeat, paler skin and headaches. Less common signs include hair loss, a sore tongue, spoon-shaped nails, restless legs and cravings to eat non-food items such as ice or paper.
Iron Deficiency Symptoms: The Main Signs to Watch For
Iron deficiency symptoms are the signs that develop when the body lacks enough iron to produce haemoglobin, the protein in red blood cells that carries oxygen around the body.
That single definition explains why the signs can seem scattered. Oxygen delivery affects almost every system at once, so a shortage can show up as exhaustion, a thumping heart, a headache and pale skin on the same afternoon. The NHS sets out the full picture on its page about iron deficiency anaemia, and it is the reference point for the symptoms described here. Not everyone gets every sign, and iron deficiency symptoms often develop gradually, which is precisely why they are so often explained away for months.
- Tiredness and a lack of energy — the most common sign of all, often described as feeling drained, heavy or unable to get going, even after a reasonable night of sleep.
- Shortness of breath — becoming breathless on stairs, hills or brisk walks that used to feel easy, because less oxygen is reaching your muscles.
- A noticeable heartbeat — palpitations, or a heart that feels as though it is racing, pounding or skipping, as it works harder to move oxygen around the body.
- Paler skin — a washed-out complexion, sometimes most obvious inside the lower eyelid or in the creases of the palm, caused by reduced haemoglobin in the blood.
- Headaches — recurring headaches, sometimes with light-headedness or dizziness when you stand up quickly.
Alongside those common signs sits a second group of less familiar symptoms that many people never connect with iron at all. Hair loss or increased shedding can occur, as can tinnitus — ringing in the ears. Some people develop a sore or smooth tongue, itchy skin, or find that food tastes strange. A craving to eat non-food items — a condition called pica, which can include ice, paper or soil — is a distinctive clue. Nails can become spoon-shaped, a change called koilonychia. Restless legs, mouth ulcers, sore cracked corners of the mouth known as angular cheilitis, and difficulty swallowing complete a list that looks random until you remember that iron supports far more than blood alone.
Two cautions matter here. First, no single symptom proves low iron: tiredness alone has dozens of possible causes, from poor sleep and stress to thyroid problems and other vitamin shortages. Our guide to vitamin B12 deficiency symptoms covers a close cousin with very similar early signs, and the two are often checked in the same set of blood tests. Secondly, a pattern matters more than any one sign: tiredness plus breathlessness plus palpitations, or tiredness alongside pica or spoon-shaped nails, is worth taking to a GP rather than pushing through until spring.
Why Iron Matters and How Anaemia Develops
Iron is a mineral with one headline job: it is an essential building block of haemoglobin. Every red blood cell carries haemoglobin, and every haemoglobin molecule uses iron to bind oxygen in the lungs and release it where tissues need it. Iron also supports muscle function, energy production and the immune system. The body recycles iron from old red blood cells and stores a reserve, mainly as ferritin, but it cannot make iron for itself: every milligram must come from food, and small amounts are lost daily through the gut, skin and, for women, menstrual blood.
Deficiency develops in stages, which is why iron deficiency symptoms can be vague at first. Initially the stores fall: ferritin drops, but haemoglobin may still sit within the normal range, and you may feel only mildly below par, if anything at all. As stores empty further, the bone marrow has less iron to work with and begins producing smaller, paler red blood cells. Once haemoglobin itself falls below the normal range, doctors call the result iron deficiency anaemia. At that stage symptoms become harder to ignore: exertion feels disproportionately hard, the heart beats faster to compensate, and the skin loses colour because there is less red pigment circulating beneath it.
The autumn timing of many searches on this topic is no coincidence. As evenings darken in October and November, tiredness is easy to attribute to the season, and winter pressure on the NHS can make people reluctant to book what feels like a minor appointment. Seasonal tiredness is real, but it does not cause palpitations, spoon-shaped nails or cravings for ice. If your tiredness matches the pattern in this guide, the season is a reason to check sooner, not to wait — a simple blood test settles the question either way.
What Causes Iron Deficiency in Adults?
Finding low iron is only half the task; finding out why it happened is the other half, and it matters just as much. Treating iron deficiency symptoms without finding the cause risks missing the underlying problem, which is why GPs take unexplained iron deficiency seriously, particularly in older adults and in anyone with bowel symptoms. The causes fall broadly into three groups: blood loss, increased need, and not absorbing or eating enough iron.
In women of reproductive age, heavy periods are the most common cause of all. Losing a large amount of blood month after month gradually drains iron stores faster than diet can replace them, and because the loss feels normal to the person experiencing it, the connection with worsening tiredness is often missed for years. Pregnancy is the other major cause in women: the body needs considerably more iron for the growing baby and the mother’s increased blood volume, which is why iron levels are checked routinely in pregnancy and supplements are commonly advised.
In men, and in women after the menopause, the cause most carefully looked for is blood loss from the stomach or bowel, because there is no routine monthly loss to explain it. Bleeding may be slow and invisible. Possible sources include stomach ulcers, inflammation of the stomach or bowel, piles, and conditions such as inflammatory bowel disease and coeliac disease, which can also impair absorption. Regular use of non-steroidal anti-inflammatory drugs — NSAIDs such as ibuprofen and aspirin — can irritate the stomach lining and cause bleeding over time, which is why a GP will ask about painkillers. Rarely, cancers of the stomach or bowel are the source of the blood loss, and that possibility is exactly why unexplained iron deficiency, a change in bowel habit or visible blood should always be investigated promptly rather than simply treated with tablets.
Diet completes the picture. A diet low in iron — for example one with little meat and few plant sources such as beans, lentils, nuts and leafy greens — can contribute, particularly when combined with heavy periods or high needs. Diet alone is less often the whole explanation in adults than blood loss, so a GP will usually still look for other causes. The NHS guide to iron in the diet explains how much iron different age groups need and where to find it, and it is the best starting point if you want to review what you eat.
How Iron Deficiency Is Diagnosed
Diagnosis is straightforward, and it starts with an ordinary GP appointment. Because the signs overlap with so many other conditions — including those covered in our guide to vitamin D deficiency symptoms, another shortage that is commonly checked in the same blood panel — a proper test is far more reliable than matching yourself against a checklist of iron deficiency symptoms at home. The usual sequence is simple, and none of it is uncomfortable beyond a standard blood sample.
- Describe the pattern to your GP. Explain how long the tiredness has lasted, any breathlessness, palpitations, hair loss or nail changes, your periods if relevant, any bowel changes, and every medicine you take, including painkillers such as ibuprofen.
- Have a full blood count. This measures your haemoglobin level and the size of your red blood cells; low haemoglobin with small, pale cells points strongly towards iron deficiency anaemia.
- Have a ferritin test. Ferritin reflects your iron stores, and a low ferritin confirms that iron deficiency is the cause of the anaemia rather than something else.
- Expect an examination and questions about the cause. The GP may examine you, ask about bleeding or bowel symptoms, and review your diet, periods and medicines to work out where the iron is going.
- Be referred if the cause is unclear. Unexplained blood loss, a change in bowel habit or other warning signs can lead to further tests or a specialist referral to find the source.
It is worth knowing that ferritin can appear misleadingly normal when you have inflammation or infection, because it also rises as part of the body’s response to illness, so a GP reads it alongside the full blood count and your symptoms. If your results come back normal but symptoms persist, say so — low iron is only one of several treatable causes of tiredness, and ruling it out is useful in itself.
Treatment, Food and Everyday Steps That Help
Once the cause is identified, treatment for iron deficiency usually has two strands running together: replacing the missing iron, and dealing with whatever caused the loss. If your haemoglobin is low, a GP will normally prescribe iron tablets — commonly ferrous fumarate or ferrous sulfate — and advise you to take them exactly as directed. Prescribed tablets contain far more iron than shop-bought multivitamins, and the course typically runs for several months: haemoglobin usually starts rising within weeks, but stores take longer to rebuild, and stopping early is a common reason symptoms drift back.
Iron tablets have a well-known practical side, and knowing it in advance helps people stick with the course. Side effects can include constipation, stomach discomfort, nausea and dark or black stools, which are expected on iron tablets and are not, on their own, a sign of bleeding — though new or worsening bowel symptoms should always be mentioned to the GP. Taking tablets exactly as your GP or pharmacist advises, and telling the practice if side effects make the course hard to complete, is better than quietly stopping: a different preparation or dose can often be arranged. Absorption details matter too. Vitamin C helps the body absorb iron, so taking tablets with a small glass of orange juice or eating vitamin C-rich foods alongside iron-rich meals can help, while tea and coffee drunk with meals can reduce absorption, so it is worth separating them by an hour or so where you can.
Food supports recovery and helps prevent a repeat once tablets finish. The richest source of well-absorbed iron is red meat, while useful plant sources include beans and lentils, nuts and seeds, dried fruit such as apricots, fortified breakfast cereals, and dark green leafy vegetables such as spinach and kale. Iron from plant foods is absorbed less easily, which makes the vitamin C pairing — peppers, citrus fruit or broccoli in the same meal — especially useful for vegetarians and vegans. Treating the cause runs in parallel: heavier periods may need their own treatment, and if NSAID painkillers are part of the picture, the GP can review alternatives. Never stop a prescribed medicine on your own; raise it at the appointment instead.
When to See Your GP Promptly
Most cases behind iron deficiency symptoms can be handled through a routine GP appointment, but some combinations of signs should move you to book promptly rather than joining a mental queue for later. Make an appointment soon if tiredness and lack of energy persist for more than a few weeks, or if they arrive with shortness of breath, a noticeable heartbeat, unusually pale skin, repeated headaches, hair loss, restless legs, spoon-shaped nails, a sore tongue or cravings for non-food items such as ice or paper. Those patterns suggest iron deficiency symptoms may already be affecting your blood count, and earlier testing means earlier treatment.
Certain signs deserve faster action still. See a GP urgently, or use NHS 111 for advice the same day, if you notice blood in your stool or vomit, black tarry stools when you are not taking iron tablets, an unexplained change in your bowel habit, difficulty swallowing, unintentional weight loss, or severe breathlessness or chest pain. Those symptoms can point to bleeding or another serious cause that needs investigation in its own right. In pregnancy, mention new exhaustion, breathlessness or palpitations at your next midwife or GP contact rather than assuming they are part of being pregnant, because iron needs rise sharply and levels are easy to check.
What are the most common iron deficiency symptoms?
The most common signs are tiredness and a lack of energy, shortness of breath, a noticeable heartbeat or palpitations, paler skin and headaches. Less common signs include hair loss, tinnitus, a sore tongue, itchy skin, food tasting strange, spoon-shaped nails, restless legs, mouth ulcers and cravings to eat non-food items such as ice or paper, a condition called pica.
What is the most common cause of iron deficiency?
Heavy periods are the most common cause in women, and pregnancy also raises iron needs considerably. In men and post-menopausal women, slow blood loss from the stomach or bowel is the cause doctors look for most carefully, including from stomach ulcers, piles, bowel conditions and regular use of NSAID painkillers such as ibuprofen and aspirin. A diet low in iron can also contribute.
How is iron deficiency diagnosed?
A GP diagnoses it with blood tests: a full blood count to check your haemoglobin and red blood cell size, and a ferritin test to measure your iron stores. The GP will also ask about periods, diet, bowel symptoms and medicines, and may examine you, because finding the underlying cause is as important as confirming the deficiency itself.
How is iron deficiency treated?
Treatment usually combines iron tablets, such as ferrous fumarate or ferrous sulfate prescribed by a GP and taken exactly as directed for several months, with treatment of the underlying cause. Iron-rich foods help recovery and prevention: red meat, beans, lentils, nuts, dried fruit, fortified cereals and dark green leafy vegetables. Vitamin C helps absorption, while tea and coffee with meals can reduce it.
What are the side effects of iron tablets?
Common side effects include constipation, stomach discomfort, nausea and dark or black stools, which are expected while taking iron tablets. If side effects make the course hard to complete, tell your GP or pharmacist rather than stopping quietly, as a different preparation or dose can often be arranged. New or worsening bowel symptoms should always be reported.
When should I see a GP about possible iron deficiency?
Book promptly if persistent tiredness comes with breathlessness, palpitations, pale skin, hair loss, restless legs or cravings for non-food items. Seek help the same day for blood in your stool or vomit, black tarry stools when you are not taking iron tablets, an unexplained change in bowel habit, difficulty swallowing, unintentional weight loss, severe breathlessness or chest pain.
Conclusion: Common, Treatable and Worth Testing
The reassuring thread running through this guide is that iron deficiency is both common and treatable. The iron deficiency symptoms most people notice first — tiredness, breathlessness, palpitations, pale skin and headaches — along with stranger clues such as pica, restless legs and spoon-shaped nails, are settled one way or the other by two ordinary blood tests, a full blood count and a ferritin level. Iron tablets, an iron-aware diet and, above all, treatment of the underlying cause resolve most cases, whether that cause is heavy periods, pregnancy, stomach or bowel blood loss, painkillers or simply eating too little iron.
If you have recognised your own exhaustion in this guide, do not put it down to darker evenings for another month — book a GP appointment, ask for your iron to be checked, and share this guide on iron deficiency symptoms with anyone you know who has been running on empty.
