Iron Deficiency Symptoms: 12 Signs You May Be Low in Iron
Iron deficiency is the most common nutritional deficiency in the world, and it is easy to miss. The symptoms of iron deficiency often build up slowly, so many people put them down to stress, poor sleep or a busy life. This guide covers the 12 most common signs, who is most at risk, the blood tests that confirm low iron, and how it is treated.
What does iron do in your body?
Your body uses iron to make hemoglobin, the protein in red blood cells that carries oxygen from your lungs to every tissue. Iron is also needed for muscle function, brain function, healthy hair and nails, and a strong immune system.
Iron deficiency usually develops in stages:
- Low iron stores: your reserves (measured as ferritin) start to drop, but hemoglobin is still normal. Many people already feel tired at this stage.
- Iron deficiency without anemia: stores are depleted and the body struggles to make new red blood cells.
- Iron-deficiency anemia: hemoglobin falls below normal and symptoms usually become more noticeable.
12 common iron deficiency symptoms
- Ongoing tiredness and low energy that does not improve with rest. This is the most common symptom.
- Weakness or reduced exercise tolerance, such as feeling worn out after stairs or a short walk.
- Shortness of breath during everyday activity.
- Pale skin, or pale inner eyelids and gums.
- Headaches, dizziness or light-headedness, especially when standing up.
- A fast or pounding heartbeat (palpitations).
- Cold hands and feet.
- Hair shedding or thinning and dry, damaged hair.
- Brittle, thin or spoon-shaped nails.
- Restless legs, an uncomfortable urge to move your legs, often at night.
- Unusual cravings (pica), such as chewing ice, clay or starch.
- A sore, smooth tongue or cracks at the corners of the mouth.
Some people also notice poor concentration, low mood, or getting sick more often. Children with low iron may be irritable, have a poor appetite or grow more slowly.
Many people with low iron have no obvious symptoms at all. A routine blood test is often the only way it is found.
Who is most at risk of iron deficiency?
- People with heavy periods. This is the most common cause in women of reproductive age.
- Pregnant people, because the body needs much more iron to support the baby.
- People who eat little or no meat, including vegetarians and vegans, if their diet is not well planned.
- Frequent blood donors.
- People with gut conditions that reduce absorption, such as celiac disease or inflammatory bowel disease, or after bariatric (weight-loss) surgery.
- People with slow blood loss from the gut, for example from ulcers, polyps or, less commonly, bowel cancer. This is especially important to check in men and in women after menopause.
- Infants, toddlers and teenagers during growth spurts.
- Endurance athletes.
- People with chronic kidney disease or heart failure.
How is iron deficiency diagnosed?
Iron deficiency is confirmed with a simple blood test. Your doctor will usually order:
| Test | What it shows |
|---|---|
| Complete blood count (CBC) | Your hemoglobin level and the size of your red blood cells. Small, pale red cells suggest low iron. |
| Ferritin | Your stored iron. A low ferritin is the most reliable sign of iron deficiency. |
| Iron and transferrin saturation | How much iron is available in your blood to make red blood cells. |
| Other tests if needed | Tests for celiac disease, kidney function, or a stool test to look for hidden bleeding, depending on the likely cause. |
One important point: ferritin can look normal or high when you have inflammation or an infection, even if your iron is low. That is why your doctor reads the results together, alongside your symptoms.
WESN Health has an on-site laboratory at our Mississauga clinics, so your blood work can often be done in the same place you see your doctor.
Why finding the cause matters
Treating low iron is only half the job. Your doctor will also want to know why your iron is low. Heavy periods, a diet low in iron, absorption problems and hidden bleeding are all treated differently. If you are a man or a post-menopausal woman with unexplained iron deficiency, your doctor may recommend further tests of your digestive tract.
How is iron deficiency treated?
1. Iron-rich foods
Diet helps prevent low iron and supports treatment, but it is rarely enough on its own to correct a real deficiency.
- Heme iron (best absorbed): red meat, chicken, turkey, fish and seafood.
- Non-heme iron: beans, lentils, chickpeas, tofu, spinach, fortified cereals, pumpkin seeds.
- Boost absorption by pairing plant iron with vitamin C, such as citrus fruit, peppers or tomatoes.
- Avoid tea, coffee and calcium supplements with iron-rich meals, as they reduce absorption.
2. Oral iron supplements
Iron tablets are usually the first treatment. They are inexpensive and work well for many people. However, they can cause constipation, nausea and stomach upset, and it can take several months to fully refill your iron stores. Taking iron every other day can improve absorption and reduce side effects for some people. Ask your doctor what suits you.
3. IV iron infusion
An IV iron infusion delivers iron directly into your bloodstream. Your doctor may recommend it when:
- Oral iron has not worked after a fair trial
- You cannot tolerate tablets because of side effects
- You have a condition that stops your gut from absorbing iron
- Your iron needs to be replenished more quickly, for example before surgery or later in pregnancy
For a detailed comparison, read our guide IV iron vs oral iron: which treatment is right for you?
When to see a doctor urgently
Book an appointment if you have ongoing fatigue or any of the symptoms above. Seek care the same day, or call 911, if you have:
- Chest pain or severe shortness of breath
- Fainting
- Black, tarry stools or blood in your stool
- Vomiting blood
- Very heavy bleeding that soaks through a pad or tampon every hour
Frequently asked questions
Ongoing tiredness that does not improve with rest is usually the first and most common sign. Others include weakness, pale skin and shortness of breath during normal activity.
Yes. Your iron stores (ferritin) can be low while your hemoglobin is still normal. Many people already have symptoms such as fatigue or hair shedding at this stage.
A ferritin test measures your iron stores and is the most useful single test. Doctors usually order it with a complete blood count (CBC), and sometimes iron and transferrin saturation.
With tablets, hemoglobin often starts to rise within a few weeks, but refilling iron stores can take three months or more. An IV iron infusion can raise iron levels much faster.
Yes. Low iron is a common, treatable cause of hair shedding, especially in women. Hair usually improves gradually once iron levels are restored.
Get your iron checked in Mississauga
If you think you may be low in iron, start with a visit to your family doctor or one of our walk-in physicians for an assessment and blood work. IV iron infusions at WESN Health are provided at Med Square Medical Centre, 4188 Living Arts Drive, Unit 5, Mississauga. Call (905) 808-3002, ask your doctor to send our Iron Infusion Referral form, or book an appointment online.
This article is for general information and does not replace advice from your doctor. If you think you are having a medical emergency, call 911 or go to the nearest emergency department.
