Can Iron Deficiency Cause Hair Loss?
Last updated: August 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
Yes — low ferritin is one of the better-established nutritional causes of hair shedding, particularly telogen effluvium in menstruating women. It is also one of the most treatable, which makes a ferritin test the highest-value thing you can do about unexplained hair loss.
Key takeaways
- Low ferritin is a well-recognised and treatable cause of shedding.
- Ferritin can be low while haemoglobin is still normal — ask for ferritin specifically.
- Expect 3–6 months of correction before hair responds.
Why ferritin rather than haemoglobin
Ferritin measures stored iron and falls before haemoglobin does. Someone can have normal haemoglobin, no anaemia, and ferritin low enough to affect hair. A standard full blood count will not show it. If you are asking about hair, ask for ferritin explicitly — it is frequently not included by default.
Why hair is sensitive to it
Hair follicles are among the most metabolically active tissues in the body, and non-essential ones. When iron is scarce the body prioritises red blood cell production and other essential functions, and follicles shift prematurely into the resting phase. The result is diffuse shedding rather than patchy loss.
Correcting it, and the timeline
Iron bisglycinate is gentler than ferrous sulphate; take it with vitamin C and away from tea, coffee, calcium and dairy. Alternate-day dosing absorbs proportionally better. Ferritin takes 3–6 months to refill, and hair lags behind that — six months is a fair point to judge it. And do not supplement iron without a confirmed deficiency; overload causes real organ damage.
Key ingredients to understand
The ingredients most relevant to this question, with what the evidence actually supports:
- Iron Bisglycinate — Iron bisglycinate is chelated iron with markedly better tolerability than ferrous sulphate — far less constipation and nausea — at comparable…
- Ferrous Sulfate — Ferrous sulphate is the cheapest and most-studied iron supplement and the standard first-line treatment for iron deficiency anaemia. It also…
- Vitamin C — Vitamin C is an essential antioxidant nutrient needed for immunity, collagen and iron absorption. For colds, regular intake may slightly shorten…
- Biotin — Biotin is the vitamin behind countless hair, skin and nail supplements — but there's little evidence it helps anyone who isn't…
Frequently asked questions
What ferritin level is low enough to matter for hair?
Thresholds are debated and higher than the anaemia threshold. This is worth discussing with a doctor rather than self-interpreting.
Why did I become iron deficient?
Worth investigating, especially for men and post-menopausal women, where it can indicate a source of blood loss.
Will iron help if my ferritin is normal?
No, and supplementing iron you do not need is harmful.
Related on FactoWiki
- Hair & Scalp Health supplements — the full category
- All health answers
- Ingredient evidence guides
- Iron Bisglycinate — ingredient guide
- Ferrous Sulfate — ingredient guide
- How we review
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