Can anaemia cause hair thinning?

Anaemia and hair: what the evidence shows

Various anaemias affect hair differently. Here is the picture across the main types.

1. Iron deficiency anaemia

Most common cause of anaemia. Low haemoglobin (under 130 g/L in men, under 120 g/L in non-pregnant women per NHS thresholds). Associated with telogen effluvium and worsened pattern hair loss. The mechanism involves both reduced oxygen delivery and direct iron deficiency effects on hair matrix cells. Treatment with iron supplementation supports hair recovery.

2. B12 deficiency anaemia

Megaloblastic anaemia caused by B12 deficiency (low intake, malabsorption, pernicious anaemia). Hair loss is documented but less common than iron-related. Symptoms include fatigue, neurological symptoms, glossitis. Treatment: B12 injections for pernicious anaemia, oral supplementation for dietary causes. Hair recovery follows treatment over 3 to 6 months.

3. Folate deficiency anaemia

Also megaloblastic anaemia. Folate (vitamin B9) deficiency from inadequate intake, malabsorption or certain medications. Less commonly associated with hair loss than iron or B12 deficiency but possible. Folic acid supplementation under GP guidance. Address underlying causes.

4. Chronic disease anaemia

Anaemia of chronic disease accompanies conditions like inflammatory bowel disease, rheumatoid arthritis, chronic kidney disease and cancers. The hair effects relate to both the underlying condition and the anaemia itself. Treatment addresses the underlying condition rather than just the anaemia.

5. Recovery follows treatment

Anaemia-related hair loss is generally reversible with proper treatment of the underlying cause. Hair shedding may continue for weeks after treatment starts then gradually decrease. Visible regrowth takes 3 to 6 months. Total recovery to baseline density may take 6 to 12 months. Patience matters during recovery.

How to investigate anaemia-related hair thinning in five steps

Use this framework to identify and address anaemia contributing to hair concerns.

Step 1. GP blood tests

Full blood count (haemoglobin, MCV, MCH). Ferritin (iron stores). B12. Folate. Thyroid function. These together identify common anaemias and other hair-relevant conditions. Discuss results with GP for personalised interpretation.

Step 2. Investigate cause of anaemia

Iron deficiency: heavy periods, poor dietary intake, GI bleeding, malabsorption. B12 deficiency: dietary patterns (especially vegan), pernicious anaemia, malabsorption. Folate deficiency: dietary patterns, certain medications, malabsorption. Address the cause not just the lab number.

Step 3. Treat per GP recommendations

Iron supplementation for iron deficiency. B12 injections (typically initial loading then 3-monthly) for pernicious anaemia. Folate supplementation for folate deficiency. Treatment for chronic disease anaemias. Follow GP guidance rather than self-treating.

Step 4. Optimise diet for ongoing support

Iron-rich foods (red meat, organ meats, beans, lentils, fortified cereals). B12 sources (animal products, fortified foods, supplements for vegans). Folate sources (leafy greens, beans, fortified grains). Adequate protein for hair structure. Balanced diet supports treatment effects.

Step 5. Allow recovery time

Hair recovery follows blood marker improvements by 3 to 6 months. The shedding pattern should improve as new hair grows in. Reassess hair density at 6 to 12 months against baseline photos. Persistent hair loss despite treated anaemia warrants dermatology referral.

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When to see your GP about hair loss

Anaemia warrants medical assessment and treatment. See your GP if any of the following apply.

• Fatigue, breathlessness or pale skin. Likely anaemia, get tested.
• Heavy menstrual bleeding. Common cause of iron deficiency anaemia.
• Vegan or vegetarian diet without B12 supplementation. Risk of B12 deficiency.
• GI symptoms with hair loss. Investigate for malabsorption or bleeding.
• Hair loss persisting despite treated anaemia. Dermatology referral.

Anaemia is one of the most common reversible causes of hair thinning. Proper GP assessment identifies the type and cause of anaemia and guides appropriate treatment. NHS treatment of anaemia is well-established with good outcomes when the underlying cause is addressed. Supplements alone without medical input are not appropriate for diagnosed anaemia.

More on hair loss causes

Anaemia connects to specific deficiencies. Can an iron deficiency cause hair loss? covers iron deficiency. Can B12 deficiency cause hair loss? covers B12. And Does a lack of iron cause hair loss? covers iron specifically.