Condition
    Moderate Evidence
    Effectiveness 3/5

    Iron for Hair Thinning & Loss

    Iron helps hair shedding when ferritin is low, and only then. Telogen effluvium is strongly associated with low ferritin, and most trichologists treat toward 70 ug/L rather than the standard lab cut-off — but regrowth is slow and requires the deficiency to be genuinely corrected.

    Overview

    Iron deficiency is one of the genuinely reversible causes of hair shedding, which makes it worth ruling out before anything else. A 2010 Cochrane review of iron supplementation in iron deficiency anaemia and a 2016 Cochrane review of daily iron supplementation in menstruating women establish that supplementation reliably corrects iron status. Correcting the deficiency is the mechanism by which hair improves; iron does not stimulate hair growth in people with normal stores.
    The typical picture is telogen effluvium: diffuse shedding across the whole scalp rather than patterned thinning, often noticed in the shower or on the pillow, and frequently starting two to three months after the trigger. Hair recovery is slow. Ferritin needs to rise and stay up, then follicles must re-enter the growth phase, so meaningful regrowth typically takes three to six months after iron status normalises. Patterned hair loss will not respond to iron at all.

    How It Works

    Hair matrix cells in the follicle bulb are among the fastest dividing cells in the body, which makes them unusually sensitive to any shortage of substrate. Iron is required by ribonucleotide reductase, the rate-limiting enzyme for DNA synthesis, so proliferation slows early when iron is short. The body also triages iron. Haemoglobin production takes priority over non-essential tissues, so hair follicles are among the first structures to be deprived.
    Deprived follicles shift prematurely from anagen, the growth phase, into telogen, the resting phase. Because telogen hairs shed roughly two to three months later, the visible shedding lags the triggering deficiency, which is why people often cannot connect the two. Ferritin thresholds for hair are debated. Many dermatologists target above 40 to 70 micrograms per litre for hair health, well above the threshold used to diagnose anaemia, though the evidence for those specific cut-offs is observational rather than randomised.

    Dosing & Protocol

    Dosing follows standard deficiency treatment: 100 to 200 mg elemental iron daily, or 60 to 100 mg on alternate days, which absorbs better and causes fewer gastrointestinal problems. Take with vitamin C, away from tea, coffee, calcium and dairy. Continue for at least three months after ferritin normalises to refill stores. Judge results at six months, not six weeks, and use reduced shedding rather than visible thickness as the first sign.

    Confirm deficiency first

    Iron only helps hair when you are deficient. Get ferritin and a full blood count before starting; supplementing when replete risks overload without any hair benefit.

    Evidence

    Two linked Cochrane reviews support this pairing: iron supplementation in iron deficiency anaemia, and daily iron supplementation for improving anaemia, iron status and health in menstruating women. Both demonstrate that oral iron reliably raises haemoglobin and ferritin. Neither used hair as an outcome measure, which is the honest limitation here: the pairing rests on correcting a deficiency known to cause telogen effluvium rather than on trials of iron for hair loss.

    Studies linked to this pairing.

    Daily iron supplementation for improving anaemia, iron status and health in menstruating women

    Score: 9/10
    2016
    meta_analysis

    Low MSY, Speedy J, Styles CE +2 more

    Daily iron supplementation raised haemoglobin and ferritin and roughly halved the risk of anaemia and iron deficiency.

    View source

    Safety

    Gastrointestinal side effects affect a large minority at treatment doses: constipation, nausea, cramping and black stools. These are the main reason people abandon treatment, and alternate-day dosing or bisglycinate usually solves it. The more important issue is that iron should not be taken without confirmed deficiency. Iron accumulates, and in undiagnosed haemochromatosis supplementation accelerates organ damage. Paediatric iron poisoning remains a leading cause of fatal overdose in young children.

    Some hair loss needs a dermatologist

    Patchy bald areas, scarring, scalp inflammation, sudden severe shedding or hair loss with other systemic symptoms need medical assessment rather than supplements.

    Interactions & Conflicts

    Iron interferes with absorption of levothyroxine, tetracyclines, quinolones, bisphosphonates and levodopa, all requiring four hours of separation. Thyroid disease deserves particular attention here because hypothyroidism itself causes hair shedding and frequently coexists with iron deficiency. In the other direction, calcium, zinc, tea, coffee and proton pump inhibitors reduce iron absorption, while vitamin C improves it substantially.
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    References

    Frequently Asked Questions

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.