Iron Deficiency — Understanding, Symptoms & Treatment
You've been told you're "just tired." That it's stress, or your age, or that your blood results are "borderline normal." But something doesn't feel right — and you know your body better than anyone. Iron deficiency is the most common nutritional deficiency in the world, and it's treatable. This is everything you need to know.
What is iron deficiency?
Iron deficiency occurs when your body doesn't have enough iron to function properly. Iron is essential for producing haemoglobin — the protein in red blood cells that carries oxygen to every tissue and organ in your body. When iron stores run low, your body can't make enough healthy red blood cells, and oxygen delivery suffers.
It's remarkably common. According to the World Health Organization, iron deficiency affects an estimated 2 billion people globally. In the UK, around 1 in 5 women of reproductive age are iron deficient. It's the single most common cause of anaemia worldwide — yet it remains widely underdiagnosed and undertreated.
Left untreated, iron deficiency doesn't just make you tired. It impairs cognitive function, weakens your immune system, causes hair loss, and can worsen heart conditions. In pregnancy, it increases the risk of premature birth and low birth weight. The longer it goes unaddressed, the harder it becomes for your body to recover on its own.
The good news: iron deficiency is entirely treatable. The key is getting the right diagnosis, understanding the underlying cause, and choosing the right treatment approach — whether that's dietary changes, oral supplements, or iron infusion therapy.
Symptoms of iron deficiency
Iron deficiency symptoms develop gradually, which is why many people live with them for months — or years — before realising something is wrong.
Why does iron deficiency happen?
Your body can't make iron — it has to come from food or supplements. Iron deficiency happens when you're losing iron faster than you're replacing it, or when your body can't absorb the iron you're taking in.
The most common causes include heavy menstrual bleeding, pregnancy, gastrointestinal conditions (coeliac disease, Crohn's, ulcerative colitis), restrictive diets, and chronic illness. Even regular blood donation can deplete your iron stores.
For many people, the problem is compounded by poor absorption. Oral iron supplements are absorbed in the gut — but only 10–20% of the iron actually reaches your bloodstream. If you have a gut condition, or if oral iron causes side effects that make you stop taking it, your levels never recover. That's when iron tablets stop being enough.
Common causes
- Heavy periods (menorrhagia)
- Pregnancy and postpartum
- Coeliac disease or IBD
- Vegetarian or vegan diet
- Gastric bypass surgery
- Chronic kidney disease
- Regular blood donation
- Endurance exercise
Treatment options for iron deficiency
Dietary changes
Iron-rich foods like red meat, liver, lentils, spinach, and fortified cereals can help maintain iron levels. Vitamin C improves absorption. Tea and coffee with meals reduce it.
Best for: Prevention, mild deficiency, or maintaining levels after treatment. Unlikely to correct established deficiency alone.
Oral iron supplements
Ferrous sulphate, ferrous fumarate, or ferrous gluconate — taken daily for 3–6 months. Widely available and often the first-line treatment recommended by GPs.
Best for: Mild to moderate deficiency with no absorption issues.
Drawbacks: Only 10–20% absorbed. Common side effects include constipation, nausea, stomach cramps, and dark stools. Up to 70% of patients experience stomach side effects from iron tablets.
IV iron infusion
A single intravenous infusion delivering up to 1000mg of iron directly into your bloodstream. Bypasses the gut entirely — no nausea, no constipation, no waiting months.
Best for: Moderate to severe deficiency, oral iron intolerance, malabsorption, pregnancy, or when fast restoration is clinically needed.
NICE recommended when oral iron is ineffective, not tolerated, or clinically inappropriate.
How IronOx Clinic helps
Specialist assessment, not a tick-box
Iron deficiency isn't one-size-fits-all. Dr Ros reviews your full blood picture, symptoms, medical history, and the likely underlying cause — not just a single ferritin number. Many patients come to us after being told their levels are 'normal' by their GP.
The right treatment for your situation
Not everyone needs an infusion. If oral iron is likely to work for you, we'll say so. If an infusion is appropriate, you'll understand exactly why. No upselling, no unnecessary treatments — just honest, specialist advice.
One appointment, not months of waiting
NHS haematology referrals can mean waiting 12–18 months. At IronOx Clinic, you can be seen this week. No GP referral needed. If an infusion is appropriate, it can often be done in the same visit.
Follow-through, not just follow-up
Your GP receives a full clinical report within 24 hours. We explain the likely cause of your deficiency and what to do next to prevent recurrence — because treating the deficiency is only half the story.
Real patient experience
"Can't praise Dr Ros enough. Staff are very friendly, the treatment room was extremely clean."
Related conditions
Iron deficiency has many faces. Explore the condition that best matches your situation.
Iron Deficiency Symptoms
Recognise the signs — fatigue, brain fog, hair loss, breathlessness, and more.
Read moreIron Deficiency Anaemia
When iron deficiency progresses to anaemia — understanding diagnosis and treatment.
Read moreLow Ferritin
Your ferritin is low but you've been told it's 'normal' — why that matters.
Read moreIron Deficiency & Hair Loss
How low iron causes hair thinning and shedding, and what restores it.
Read moreIron Infusion for Heavy Periods
Heavy menstrual bleeding is the leading cause of iron deficiency in women.
Read moreIron Infusion in Pregnancy
Safe, fast iron restoration when oral supplements aren't enough during pregnancy.
Read moreIron Infusion Before Surgery
Low haemoglobin before an operation risks delays and transfusions. IV iron corrects it fast.
Read moreIron & Fertility
Low iron affects ovulation, implantation, and IVF outcomes. Optimise before conceiving.
Read moreIron Tablets Not Working
Why oral iron fails for many people — and what to do next.
Read moreIron deficiency — common questions
Iron deficiency means your body's iron stores are depleted — your ferritin level is low. Anaemia is a further stage where iron levels have dropped enough to reduce your red blood cell count, measured by haemoglobin (Hb). You can be iron deficient without being anaemic, and still experience significant symptoms like fatigue, brain fog, and hair loss.
A ferritin level below 30 µg/L is generally considered iron deficient, though symptoms can occur even with levels in the 30–50 range. The NHS often uses a threshold of 15 µg/L for anaemia diagnosis, which means many people with genuine iron deficiency are told their results are 'normal'. A specialist assessment considers your ferritin alongside your symptoms and full blood picture.
Yes — mild iron deficiency can sometimes be treated with dietary changes and oral iron supplements. However, oral iron has poor absorption (only 10–20% is absorbed), causes side effects like constipation and nausea, and can take 3–6 months to restore levels. Iron infusion is recommended when oral iron hasn't worked, isn't tolerated, or when iron levels need restoring quickly.
With oral supplements, it can take 3–6 months to fully restore iron levels. With an iron infusion, most patients notice symptom improvement within 1–2 weeks, and ferritin levels typically normalise within 4–6 weeks. The speed of recovery depends on the severity of your deficiency and the underlying cause.
No. You can self-refer directly to IronOx Clinic. If you have recent blood results (within 3 months), bring them along — you may not need additional testing. If you don't have recent results, we can arrange blood testing as part of your assessment.
Medically reviewed by Dr Ros Jabar, GMC-registered doctor and Medical Director at IronOx Clinic. Last reviewed May 2026.
Don't let iron deficiency hold you back
Get a specialist assessment and find out exactly what's going on — and what to do about it. No referral needed, appointments available this week.