Do iron supplements help with hair loss?

Nobody has shown that they do. A 2023 systematic review of 30 studies, 17 of them randomized trials, looked at supplements for hair loss in people without a known deficiency. It listed zinc, tocotrienol and several branded blends among the better-supported options, and iron alone was not on the list. That absence means no qualifying iron-only study, which is different from proof that iron does nothing. What does exist is a link. Across 36 observational studies with 10,029 participants, women with non-scarring hair loss had ferritin, the blood marker of iron stores, about 18.5 units lower than women without it.

Unsettled. Low iron stores and shedding hair travel together in women. Whether iron tablets bring the hair back is a question no randomized trial has answered. The one randomized hair trial with iron in it used a tablet of several ingredients and excluded people who were iron deficient. Every result about iron given for hair comes from studies without randomization.

What the trials found

The one randomized trial with iron in it

In six Italian dermatology clinics, 83 adults with pattern hair loss or chronic shedding stayed on their hair-loss drugs and were randomized to add a daily tablet of collagen, amino acids, iron and selenium, or to add nothing. After 12 weeks the global hair score had risen by 1.67 points with the tablet and 0.66 without, a difference of 1.01 (95% CI 0.52 to 1.50). The assessors were blinded, and there was no placebo. The iron dose is not given, and iron deficiency was a reason to be excluded, so the result cannot be credited to iron.

Iron given for a measured deficiency

In a pilot without randomization, 116 premenopausal blood donors with ferritin of 10 ng/ml or less and no anemia took iron for 16 weeks and were compared with 108 earlier donors. Mean ferritin rose from 7.12 to 25.2 ng/ml, and hair loss was among the complaints reported as resolved. There was no blinding, the hair loss was self-reported, and 40 percent dropped out.

A chart review at NYU went the other way. Of 131 patients with non-scarring hair loss, 42 were given supplements for a measured deficiency, most often low ferritin. In a multivariate analysis the supplements did not significantly change hair density (P=0.73) or hair diameter (P=0.96). Ferritin was low in only 6.5 percent of these patients, follow-up was short, and several kinds of supplement were pooled.

What iron does when stores are low and blood count is normal

This is the group hair clinics see most. A 2018 review of 18 randomized trials enrolling 1170 adults with low iron and no anemia found that iron raised ferritin in 14 of the trials. In the 4 trials with 714 participants that measured it, iron eased self-reported fatigue by a standardized difference of -0.38 (95% CI -0.52 to -0.23). It made no difference to objective measures of physical capacity. The review did not measure hair.

The link, in observational data

The 2022 meta-analysis behind the 18.5 figure pooled 36 studies and had no treatment arms. The paper prints the unit as ng/dL, which is most likely ng/mL. In a case-control study of 60 women aged 15 to 45, ferritin at or below 30 ng/mL went with 21 times the odds of diffuse shedding, with a 95% confidence interval from 4.2 to 105. That is a small study, and an odds ratio is not the same as a risk. In 5110 French women aged 35 to 60, 59 percent of those reporting excessive hair loss had ferritin under 40, against 48 percent of the rest. In a Korean chart review, women with female pattern hair loss had mean ferritin of 49 mcg/L against 78 in matched healthy women.

Two findings narrow the link. After bariatric surgery, 18 studies with 2538 patients found hair loss in 57 percent, tied to lower ferritin (standardized difference -0.22, 95% CI -0.38 to -0.05) but not to serum iron, and also tied to low zinc and folate. Iron is one of several shortfalls there. In alopecia areata, the patchy autoimmune kind, a meta-analysis of 10 studies with 764 people found no difference in serum iron (P=0.36) or ferritin (P=0.37) against healthy controls. Zinc and selenium were lower. Iron belongs to the question of diffuse shedding in women, and these data do not support it for patchy hair loss.

Who should be careful

Iron tablets have a known cost. In a meta-analysis of 43 randomized trials with 6831 adults, ferrous sulfate, the standard tablet, more than doubled the odds of gut side effects against placebo (odds ratio 2.32, 95% CI 1.74 to 3.08). Those trials were mostly in anemia, pregnancy and bowel disease, not in hair loss.

Not for everyone. The NIH sets the upper limit for iron at 45 mg a day for adults, and 40 to 45 mg for infants, children and teenagers, and names stomach upset, constipation, nausea and diarrhea from high-dose supplements. The limit is set on the gut effects of iron salts, and treatment doses above it are given under medical supervision. It also notes that supplements with 25 mg of iron or more can lower zinc absorption. The NIH gives no size for that effect. Low zinc turned up in two of the hair-loss reviews above, so the interaction is worth knowing about if you take high-dose iron for hair.

We have no card on iron for hair in pregnancy, in children or alongside specific medicines. That is a gap in what we found, and it should not be read as a sign of safety.

What expert bodies say

The only expert body on our cards for this question is the NIH Office of Dietary Supplements, and it speaks to dose and side effects, not to hair. We found no dermatology body position that we could check against a source and put on a card.

How we searched

What would change this answer

• A randomized, placebo-controlled trial of plain iron tablets in women with diffuse shedding and low ferritin, with hair counts as the outcome. We found none, in print or registered.
• A trial of the ferritin cut-off. Papers use different thresholds, 30 in one study above and 40 in another, and none has been tested as a point where treating helps hair.
• Results from the two trials we could not read. If either reports hair counts against a control, it would be the first direct evidence on this page.

How much iron you need, who runs short and where it comes from in food is in the iron guide. Iron for anemia, a separate question, has its own evidence page.

Sources

1. ev-irh-01 · Meta-analysis or systematic review · systematic review of randomized and non-randomized intervention studies · n = 30 studies
   Studies of nutritional interventions with the highest-quality evidence showed the potential benefit of Viviscal, Nourkrin, Nutrafol, Lamdapil, Pantogar, capsaicin and isoflavone, omegas 3 and 6 with antioxidants, apple nutraceutical, total glucosides of paeony and compound glycyrrhizin tablets, zinc, tocotrienol, and pumpkin seed oil.
   
   Who: individuals with alopecia or hair loss without a known baseline nutritional deficiency
   Effect: 17 RCTs, 11 non-randomized clinical studies, 2 case series; no diet-based interventional study met inclusion criteria
   Certainty: Not pooled; quality graded by Oxford CEBM. Absence of iron from the list means no qualifying iron-only study, not proof of no effect.
   JAMA Dermatol, 2023 · checked 2026-10-06 · we read the abstract
2. ev-irh-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6831
   Ferrous sulfate supplementation significantly increased risk of GI side-effects versus placebo with an odds ratio (OR) of 2.32 [95% CI 1.74-3.08, p<0.0001, I2 = 53.6%] and versus i.v. iron with an OR of 3.05 [95% CI 2.07-4.48, p<0.0001, I2 = 41.6%].
   
   Who: adults in RCTs of ferrous sulfate versus placebo or intravenous iron
   Effect: GI side effects OR 2.32 (95% CI 1.74 to 3.08) vs placebo, I2 53.6%; OR 3.05 (2.07 to 4.48) vs IV iron; no dose relationship
   Certainty: Trials were mostly in iron deficiency anemia, pregnancy and IBD, not in hair loss.
   PLoS One, 2015 · checked 2026-10-06 · we read the abstract
3. ev-irh-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 1170
   Using a Mantel-Haenszel random-effects model, iron supplementation was associated with reduced self-reported fatigue (standardised mean difference (SMD) -0.38; 95% CI -0.52 to -0.23; I2 0%; 4 trials; 714 participants) but was not associated with differences in objective measures of physical capacity, including maximal oxygen consumption (SMD 0.11; 95% CI -0.15 to 0.37; I2 0%; 9 trials; 235 participants) and timed methods of exercise testing.
   
   Who: adults who were iron deficient but non-anemic, 18 trials enrolling 1170 patients
   Effect: self-reported fatigue SMD -0.38 (95% CI -0.52 to -0.23), 4 trials, 714 participants; ferritin rose in 14 trials
   Certainty: Shows iron corrects low stores in the group that hair clinics see most, but gives no hair outcome.
   BMJ Open, 2018 · checked 2026-10-06 · we read the abstract
4. ev-irh-04 · Randomized controlled trial(s) · randomized assessor-blinded controlled trial, add-on to drug treatment, no placebo · n = 83
   After 12 weeks both the two groups showed an increase in the GAS, that was higher in group A compared to group B (1.67 ± 0.16 and 0.66 ± 0.20, respectively, mean difference 1.01 ± 0.25, 95% CI: 0.52–1.50) (Figure 2).
   
   Who: 83 subjects with AGA, FAGA or chronic TE in six Italian dermatology clinics; iron deficiency was an exclusion criterion
   Effect: global assessment score at 12 weeks 1.67 vs 0.66, mean difference 1.01 (95% CI 0.52 to 1.50)
   Certainty: Multi-ingredient product, no placebo, open patient-rated outcomes; the iron dose is not given and iron-deficient people were excluded, so the effect cannot be credited to iron.
   Skin Res Technol, 2023 · checked 2026-10-06 · we read the fulltext
5. ev-irh-05 · Observational data · systematic review and meta-analysis of observational studies · n = 10,029
   Women with nonscarring alopecia had lower ferritin values at MD = -18.51 ng/dL (-25.85; -11.16, p < 0.01).
   
   Who: women with and without nonscarring alopecia, 36 studies; 18 compared mean ferritin
   Effect: ferritin MD -18.51 (-25.85 to -11.16) as reported in ng/dL; prevalence of ferritin 10 to 15 and below 21% (12 to 29)
   Certainty: Cross-sectional comparisons cannot show that low ferritin causes hair loss; unit printed as ng/dL in the paper is likely ng/mL. No intervention arms.
   Skin Appendage Disorders, 2022, Iron Deficiency and Nonscarring Alopecia in Women: Systematic Review and Meta-Analysis · checked 2026-10-06 · we read the abstract
6. ev-irh-06 · Observational data · case-control study · n = 60
   Odds ratio (95% confidence interval) for diffuse telogen hair loss was 21.0 (4.2-105.0) at serum ferritin levels < or =30 ng/mL.
   
   Who: 30 consecutive women with diffuse telogen hair loss and 30 women without hair loss, childbearing age
   Effect: OR 21.0 (95% CI 4.2 to 105.0) at ferritin <=30 ng/mL; mean ferritin 16.3 vs 60.3 ng/mL
   Certainty: Small, very wide interval; odds, not risk.
   Acta Dermatovenerol Croat, 2009 · checked 2026-10-06 · we read the abstract
7. ev-irh-07 · Observational data · cohort, cross-sectional analysis · n = 5110
   Among the women affected by excessive hair loss, a larger proportion of women (59%) had low iron stores (< 40 microg/L) compared to the remainder of the population (48%).
   
   Who: 5110 women aged 35 to 60, questionnaire on hair loss and serum ferritin
   Effect: ferritin <40 microg/L in 59% with excessive hair loss vs 48% of the rest
   Certainty: Self-reported hair loss; association only.
   Eur J Dermatol, 2007 · checked 2026-10-06 · we read the abstract
8. ev-irh-08 · Observational data · single-center retrospective chart review · n = 131
   Multivariate regression analysis showed that supplementation did not significantly impact hair density or diameter (P=0.73; P=0.96, respectively).
   
   Who: 131 patients with non-scarring alopecia with at least two hair specialist visits; 42 received supplementation for their deficiency
   Effect: supplementation vs none: hair density P = 0.73, hair diameter P = 0.96 in multivariate regression
   Certainty: Few patients were deficient (ferritin low in 6.5%), short follow-up, supplements of several kinds pooled.
   J Drugs Dermatol, 2021 · checked 2026-10-06 · we read the abstract
9. ev-irh-09 · Observational data · non-randomized controlled pilot with historical controls · n = 116
   Significant results were serum ferritin increase (from a mean value of 7.12 to 25.2 ng/ml), resolution of prostration, fatigue, sleep disturbances, tension in the neck, hair loss and nail breakage.
   
   Who: 116 premenopausal female blood donors aged 50 or under, ferritin <=10 ng/ml without anemia, against 108 retrospective controls
   Effect: ferritin 7.12 to 25.2 ng/ml; hair loss among symptoms reported as resolved; 60% completed
   Certainty: No randomization, no blinding, hair loss self-reported, 40% dropout.
   Vox Sang, 2011 · checked 2026-10-06 · we read the abstract
10. ev-irh-10 · Observational data · systematic review and meta-analysis of observational studies · n = 2538
    Serum zinc (standardized mean difference (SMD), - 1.13; 95% CI, - 2.27 to 0.01, p = 0.05), folic acid (SMD = - 0.88, 95% CI - 1.29 to - 0.46, p < 0.0001), and ferritin levels (SMD, - 0.22; 95% CI, - 0.38 to - 0.05; p = 0.01), but not serum iron and vitamin B12, were associated with hair loss following MBS.
    
    Who: patients after metabolic and bariatric surgery, 18 studies
    Effect: incidence 57% (95% CI 42 to 71%); ferritin SMD -0.22 (-0.38 to -0.05); serum iron not associated
    Certainty: Observational; zinc and folate were also linked, so iron is one of several deficits.
    Obes Surg, 2021 · checked 2026-10-06 · we read the abstract
11. ev-irh-11 · Observational data · meta-analysis of observational studies · n = 764
    However, there was no significant difference between the AA patients and controls in the levels of serum copper (P = 0.81), serum iron (P = 0.36), serum ferritin (P = 0.37) and serum magnesium (P = 0.07).
    
    Who: patients with alopecia areata and healthy controls, 10 studies
    Effect: serum iron P = 0.36, ferritin P = 0.37 vs controls; zinc and selenium lower (P < 10-4)
    Certainty: Few small studies; patchy autoimmune hair loss differs from diffuse shedding.
    J Dermatol, 2017 · checked 2026-10-06 · we read the abstract
12. ev-irh-12 · Observational data · retrospective chart review with matched controls · n = 420
    Serum ferritin concentration (FC) was lower in patients with FPHL (49.27 ± 55.8 µg/L), compared with normal healthy women (77.89 ± 48.32 µg/L) (P < 0.001).
    
    Who: 113 FPHL and 97 MPHL patients with 210 age-sex matched healthy controls
    Effect: ferritin 49.27 vs 77.89 microg/L in women (P < 0.001)
    Certainty: Hospital controls; association only.
    J Korean Med Sci, 2013 · checked 2026-10-06 · we read the abstract
13. ev-irh-13 · Position of an expert body · agency fact sheet · n = —
    The Tolerable Upper Intake Level for iron is 45 mg for adults, and it ranges from 40 mg to 45 mg for infants, children, and adolescents, depending on age.
    
    Who: General population, NIH Office of Dietary Supplements iron fact sheet
    Effect: UL 45 mg/day adults, 40 to 45 mg/day for infants, children and adolescents
    Certainty: The UL is set on GI effects of iron salts; treatment doses above it are prescribed under medical supervision.
    NIH Office of Dietary Supplements, Iron fact sheet for health professionals · checked 2026-10-06 · we read the section
14. ev-irh-14 · Position of an expert body · agency fact sheet · n = —
    However, supplements containing 25 mg iron or more can reduce zinc absorption and plasma zinc concentrations [3,87,88].
    
    Who: General population, NIH Office of Dietary Supplements iron fact sheet
    Effect: supplements with >=25 mg iron reduce zinc absorption and plasma zinc
    Certainty: Agency summary without effect sizes; the hair link to zinc rests on other cards.
    NIH Office of Dietary Supplements, Iron fact sheet for health professionals · checked 2026-10-06 · we read the section