Signs of low iron: symptoms and tests

What are the signs of low iron?

Tiredness and lack of energy, shortness of breath, noticeable heartbeats (palpitations), paler skin than usual and headaches. Those are the five symptoms the NHS lists first for iron deficiency anaemia, the stage where low iron has reduced the haemoglobin in your blood. Haemoglobin carries oxygen around the body, and with too little of it your blood can't carry enough, which is why you feel tired.

Each of the five has plenty of other possible causes, and paleness is harder to judge on darker skin. Symptoms are a good reason to get checked, but on their own they can't show that iron is the problem.

Symptoms can start before anaemia does. NHS Blood and Transplant's leaflet on iron says low iron alone can cause restless legs, pica, brittle nails, hair loss, dizziness and headaches.

What are the weird signs of iron deficiency?

The odder signs are among the ten less common symptoms the NHS lists, which with the five above make 15 in all:

• ringing, buzzing or hissing noises in your head (tinnitus)
• food tasting strange
• feeling itchy
• a sore tongue
• hair loss, noticed as more hair coming out when you brush or wash it
• wanting to eat things that aren't food, such as paper or ice (pica)
• finding it hard to swallow
• painful sores in the corners of your mouth
• nail changes, such as spoon-shaped nails
• restless legs syndrome

We couldn't find a list of "5 weird signs" from any medical body. The ones that tend to surprise people are pica (often a habit of chewing ice), tinnitus, restless legs, a sore tongue and spoon-shaped nails, which curve upwards at the edges. Difficulty swallowing needs quicker attention: the NHS advises an urgent GP appointment or a call to 111 for any swallowing problem, whatever you think is causing it.

Are there signs of low iron in your eyes?

Yes, one: a pale lining inside the lower eyelid. To check for anaemia, doctors gently pull the lid down to look at the lining (the palpebral conjunctiva), which is normally clearly red and turns pale pink when haemoglobin is low. A UK clinical skills review notes it is one of the few places, along with the palms and nail beds, where pallor can be judged on any skin colour.

It's a rough sign. In a 1997 study of 302 hospital patients, obvious pallor raised the odds of severe anaemia (haemoglobin of 90 g/L or below) about four and a half times, but a normal-looking eyelid didn't rule it out, and the sign is less reliable when anaemia is mild. Dark circles and eye twitching, which some websites add, are not on the NHS list. Pale eyelids are a reason to book a blood test.

Which blood tests check for low iron?

A GP will usually do a full blood count (FBC), which measures your haemoglobin and the size of your red blood cells, and often a ferritin test, which reflects how much iron you have stored. The same blood count helps show whether you might have a different type of anaemia, such as vitamin B12 deficiency or folate deficiency anaemia. If the cause isn't clear, the GP may test a stool sample for hidden blood (a FIT test). The British Society of Gastroenterology (BSG) recommends that anyone with confirmed iron deficiency anaemia also has a urine test and a blood test for coeliac disease.

What is a ferritin blood test?

Ferritin is a protein that stores iron, and the level in your blood reflects your iron stores. The BSG calls it the single most useful marker of iron deficiency anaemia. Ferritin also rises with infection and inflammation, so it can look normal, or even high, while your stores are low. For that reason, the BSG notes, a cut-off of 45 µg/L has been suggested as the best balance in practice between catching iron deficiency and raising false alarms.

What should ferritin levels be?

Within the reference range of the lab that tests you, and NHS labs set different ones. Here is how three of them set their adult ranges:

A woman with a ferritin of 20 µg/L would be in range in Bristol and below it in Liverpool. The BSG gives two fixed points: below 15 µg/L means your iron stores are used up, and below 30 µg/L generally means they're low.

Haemoglobin ranges vary too. Gloucestershire Hospitals uses 130 to 180 g/L for men and 115 to 165 g/L for women, while the World Health Organization defines anaemia as below 130 g/L in men, 120 g/L in non-pregnant women and 110 g/L in later pregnancy. The BSG says each lab should use its own lower limit, in line with those WHO figures. So any iron levels chart, this one included, is a rough guide: the range printed on your own result is the one that counts, and your GP will read it alongside your symptoms.

What causes low ferritin with normal haemoglobin?

Usually the same things that cause anaemia, caught earlier. The body uses up its stored iron before it runs short of haemoglobin, a stage the BSG calls non-anaemic iron deficiency. Heavy periods, pregnancy, low intake, blood donation and poor absorption (from coeliac disease, for example) are common reasons, and the cause still needs finding. A 2018 systematic review found that iron reduced self-reported tiredness in adults at this stage (four trials, 714 people) but made no difference to measured physical fitness.

Who is most likely to have low iron?

Girls and women of childbearing age. In the latest UK National Diet and Nutrition Survey (2019 to 2023), 34% of women aged 19 to 64 and 49% of girls aged 11 to 18 got less iron from food than the lower reference nutrient intake, a level expected to meet the needs of only 2.5% of people. For men aged 19 to 64 the figure was 2%. Diet surveys rely on people recalling what they ate, so treat these as estimates. Blood tests in the same survey found both low haemoglobin and low iron stores in 9% of girls aged 11 to 18.

Other groups at higher risk:

• people with heavy periods, who the NHS says may need iron supplements
• pregnant women, for whom low iron is a very common cause of anaemia
• blood donors, since each donation removes iron along with red blood cells
• vegetarians and vegans, who the NHS says are more likely to have lower iron stores because plant iron is harder to absorb
• people taking anti-inflammatory painkillers such as ibuprofen or aspirin regularly, or long-term stomach acid medicines (proton pump inhibitors)
• people with coeliac disease or other conditions that affect absorption

In men and in women after the menopause, the BSG says iron deficiency anaemia is often caused by slow blood loss from the gut. NHS Blood and Transplant says iron deficiency should always be investigated when the cause isn't clear, especially in these groups, because it can be the first sign of a serious condition such as bowel cancer.

Should you take iron if you think you're low?

Not until you've had a blood test. Tiredness has many causes, and the NHS advises anyone who feels tired but hasn't been diagnosed with iron deficiency anaemia to talk to a doctor or pharmacist before taking ferrous sulfate, the standard iron tablet.

Some people already have too much iron. Haemochromatosis is an inherited condition in which iron slowly builds up over years. It most often affects people of white northern European background and is particularly common where many people have Celtic roots, such as Ireland, Scotland and Wales. The first symptom the NHS lists for it is feeling very tired all the time, and people being treated for it are usually advised to avoid iron and vitamin C supplements. If you do turn out to be low, your GP will also look for the reason.

Prescribed iron is a much higher dose than a multivitamin. One ferrous sulfate tablet gives 65 mg of iron, against up to 14 mg in a multivitamin with iron, and the NHS says 17 mg a day or less from supplements is unlikely to cause harm. Our guide to iron tablets covers how long they take, side effects and how to take them.

What foods have iron?

The NHS lists liver, red meat, beans, nuts, dried fruit, fortified breakfast cereals and soy bean flour as good sources. Women aged 19 to 49 need 14.8 mg of iron a day. Men, and women aged 50 and over, need 8.7 mg, though women still having periods after 50 may need the higher amount. Here is what common UK foods provide:

Iron per 100 g is from the UK government's food composition dataset (CoFID 2021); portion figures are our arithmetic. Fortified cereals vary by brand, so check the label. The NHS advises avoiding liver in pregnancy because of its high vitamin A content, and government advice is to limit red and processed meat because of a probable link with bowel cancer.

What are some iron-rich snacks?

Pumpkin seeds, cashew nuts, hummus and dried fruit are easy snacks with some iron, though one snack gives a small share of the day's needs. A 30 g portion of pumpkin seeds gives about 3 mg (see the table above). A hospital dietetics leaflet puts 30 g of cashew nuts at about 2 mg, a quarter pot (50 g) of hummus at 1 mg and a tablespoon of tahini at 1 mg. Another trust's leaflet gives 30 g of fortified cereal an average of 2.5 mg, and fortified bran flakes more. Leaflets differ a little, so treat these as rough guides. If you eat little or no meat, plant snacks matter more because plant iron is harder to absorb, so pair them with fruit or another source of vitamin C.

Which fruit is high in iron?

Dried fruit is the fruit that gets listed, and it gives modest amounts. The NHS names dried fruit such as dried apricots among iron-containing foods. A hospital dietetics leaflet gives 30 g of sultanas, raisins, dates or apricots 0.5 to 1.5 mg, two dried figs (40 g) 1.5 mg and six prunes (60 g) 1.5 mg, and the leaflets we read list no fresh fruit as an iron source. Fruit does help in another way: vitamin C in citrus fruit and other fruit helps you absorb iron from plant foods eaten at the same meal.

Which drinks are high in iron?

Few drinks supply much iron. The exceptions are iron-fortified ones: a hospital leaflet gives about 3.5 to 5 mg for a serving of fortified malted drink powder (5 to 6 teaspoons) and notes that some milks are fortified, so check the label. Tea and coffee go the other way and reduce how much iron you absorb (see below). Fruit juice isn't listed as an iron source in the leaflets we read, but a glass of orange juice with a meal supplies vitamin C, which helps absorption. One trust leaflet lists a 150 ml glass of red wine at 1.5 mg, which is no reason to drink it for iron. We found no UK source giving an iron figure for prune juice.

Haem and non-haem iron

Iron from meat and fish (haem iron) is absorbed more easily than the iron in plants, eggs and fortified foods (non-haem iron). In single-meal studies reviewed by the government's Scientific Advisory Committee on Nutrition (SACN), people absorbed 20 to 30% of haem iron against 5 to 15% of non-haem iron. Your body also absorbs more when its stores are low. Eating plant sources with vitamin C, or with some meat or fish, helps you absorb more of their iron.

NHS dietitians suggest having vegetables, fruit or fruit juice, especially citrus, with meals that contain iron. A glass of orange juice with fortified cereal is one easy way to do it.

Does tea or coffee stop iron absorption?

They reduce it, mostly from plant foods eaten at the same time. In one study reviewed by SACN, the polyphenols in a cup of tea or instant coffee cut non-haem iron absorption from a bread meal by 60 to 90%. Coffee has about half the effect of tea, and milk doesn't change it. Calcium and the phytic acid in wholegrain cereals also reduce absorption. NHS Blood and Transplant suggests keeping tea and coffee an hour away from meals, though SACN notes that single-meal studies may overstate these effects across a whole diet.

Where Natura fits

Daily Iron, in the Natura cabinet (coming soon), is 14 mg of iron as bisglycinate in one capsule, below the 17 mg a day the NHS says is unlikely to cause harm from supplements. Iron contributes to the normal formation of red blood cells and haemoglobin and to the reduction of tiredness and fatigue. It's a food supplement for topping up intake and isn't a treatment for iron deficiency anaemia, so if you think you're low, get the blood test first. You'll find it with the daily bottles, and paired with Daily B12 in the Blood Pack.