Does selenium help with hair loss?

There is no trial evidence that it does, and good trial evidence that extra selenium can cause hair loss. We found no randomized trial of selenium alone as a treatment for any kind of hair loss. In the SELECT trial, 17,448 healthy men took 200 mcg of selenium a day or placebo, and those on selenium had a 28 percent higher risk of alopecia (risk ratio 1.28, 95% CI 1.07 to 1.53). A 2020 Cochrane review rated that finding high certainty.

Myth. Selenium supplements as a hair treatment rest on no trial at all. The one large randomized trial that measured hair found more alopecia on selenium, in healthy men.

Risk with selenium supplements against placebo

Harms in the SELECT trial

Above 1 means more cases on selenium. All four rows come from one trial, SELECT, read by two Cochrane reviews with slightly different intervals. The abstracts give relative risks only, so the number of extra cases per 1000 men cannot be shown. Sources: cards ev-sehl-01 and ev-sehl-02 below.

What the trials found

Selenium alone

Three Cochrane reviews of selenium for cancer and heart disease prevention report the same hair signal, and all three take it from SELECT. The 2020 review found the increase in alopecia with high certainty, along with more mild dermatitis (risk ratio 1.16, 1.04 to 1.31). The 2013 review, covering 12 trials and 19,715 people, gives alopecia a risk ratio of 1.28 (1.01 to 1.62). The 2018 review of 10 trials and 27,232 people says that in SELECT selenium increased the risks of alopecia and dermatitis. None of these abstracts gives the absolute numbers of men affected, so we cannot say how many extra cases the 28 percent is.

Selenium inside mixed supplements

A 2023 systematic review in JAMA Dermatology looked at 30 studies of supplements for hair loss in people without a known deficiency. It listed the products with the best evidence, among them several branded blends, zinc, tocotrienol and pumpkin seed oil. Selenium on its own was not on the list. Some of the listed blends contain selenium, so its share of any effect cannot be separated.

One randomized trial shows the problem. 83 adults with pattern hair loss or chronic telogen effluvium, already on drug treatment, took a tablet of collagen, amino acids, iron and selenium or nothing extra for 12 weeks. Photo scores improved more with the tablet (1.67 against 0.66 on a global assessment score). There was no placebo, and the tablet held four kinds of ingredient, so the result says nothing about selenium itself.

Low selenium in alopecia areata

Unsettled. Two meta-analyses of observational studies disagree. A 2017 analysis of case-control studies found lower blood selenium in people with alopecia areata than in healthy controls. A 2020 analysis of 27 studies found no significant difference, with a standardized difference of 0.47 and an interval from -2.72 to 3.65. Even if the levels were lower, that would be an association, and a low level could follow the disease rather than cause it.

Who should be careful

Hair loss is the best-known sign of too much selenium. The NIH Office of Dietary Supplements lists hair loss and brittle or lost nails as the most common signs of chronically high intake, and the US upper limit for adults is 400 mcg a day.

Selenium, micrograms a day

The dose that raised alopecia in SELECT sits below both official upper limits. The toxicity bar starts at 330 and its whisker runs to 450, the range the Nordic review gives. Sources: cards ev-sehl-01, ev-sehl-10 and ev-sehl-12 below.

Poisonings show the same pattern at doses no one would choose. In a 2008 US outbreak, 201 people took a liquid supplement that carried about 200 times the selenium on its label. 72 percent lost hair, and in 29 percent the hair loss was still there 90 days later. In Enshi County, China, a food-borne poisoning in the 1960s, with intakes near 5 mg a day, affected almost half the people in the worst villages, and loss of hair and nails was the most common sign.

Percent of people poisoned by a misformulated supplement

A liquid supplement carried about 200 times the selenium on its label. These are proportions from an outbreak investigation, so no intervals are drawn. Source: card ev-sehl-08 below.

Not for everyone. Brazil nuts are the ordinary food that can reach these levels. The NIH Office of Dietary Supplements gives 68 to 91 mcg of selenium per nut and warns that eating them regularly could cause toxicity. If you already take a supplement with selenium, a daily handful of Brazil nuts adds up fast. Upper limits for children are lower, from 45 mcg a day in infants depending on age.

What expert bodies say

The US upper limit for adults is 400 mcg a day, and for infants, children and teenagers it ranges from 45 to 400 mcg by age. The Nordic Nutrition Recommendations review cites a lower European limit of 255 mcg a day for adults, set by EFSA, and places toxic effects on skin, nails and hair above 330 to 450 mcg a day. The bodies disagree on the exact line.

In the EU, a label may say that selenium contributes to the maintenance of normal hair. That is a general function claim tied to getting enough selenium. It does not say that extra selenium treats hair loss, and no body we found recommends selenium for that purpose.

How we searched

Searched: a local copy of the PubMed baseline, on 7 October 2026, for selenium with hair loss, alopecia, hair or telogen effluvium. The broad query returned 176 records and we reviewed the top 40. Narrower queries on toxicity and SELECT (46 records), on poisoning outbreaks (14), on supplements for hair loss in general (17) and on adverse skin effects in trials (9) followed. We also read the NIH selenium fact sheet, the EU claims register, ClinicalTrials.gov and Retraction Watch. None of the papers used has been retracted. A web search for 2025 reviews found mostly blogs.

Included: three Cochrane reviews that report SELECT, a systematic review of supplements for hair loss, one randomized trial of a mixed supplement, two observational meta-analyses on alopecia areata, two poisoning reports, the NIH fact sheet, the Nordic review and the EU claim.

Excluded: reviews of micronutrients and trace elements whose abstracts give no selenium-specific number for hair, a high-dose prostate cancer trial that did not quantify hair changes, a single occupational case report, and selenium sulfide shampoo, which is a topical dandruff treatment and not dietary selenium.

What we read: abstracts from the PubMed baseline, with every quotation checked against the abstract text, and the agency pages themselves.

What we could not get: the full text of the 2023 JAMA Dermatology review, and a 2025 meta-analysis of nutraceuticals for hair loss in Archives of Dermatological Research that is not in our corpus.

What would change this answer

A placebo-controlled trial of selenium in people with documented low selenium status and hair loss. That is the one group where a benefit is plausible, and we found no trial of it.
Absolute numbers from SELECT on how many men lost hair in each group, which would turn the 28 percent into a count.

More on selenium: selenium and the thyroid and the Brazil nuts page. Other nutrients and hair loss: zinc and iron.

The rest of the nutrient, in one place. Selenium: a deficiency that kills and a supplement that does not help → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The food behind this question

Brazil nuts: the one food where a handful can be too much — numbers, evidence and safety

The full guide

Selenium: a deficiency that kills and a supplement that does not help

The same question for other foods (hair loss)

Sources

ev-sehl-01 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 17448
Selenium in men results in little to no difference in lung cancer incidence (RR 1.11, 95% CI 0.80 to 1.54; 1 RCT, 17448 participants; high-certainty evidence) and lung cancer mortality (RR 1.09, 95% CI 0.72 to 1.66; 1 RCT, 17448 participants; high-certainty evidence) and increases the risk for grade 1 to 2 dermatitis (RR 1.16, 95% CI 1.04 to 1.31; 1 RCT, 17448 participants; high-certainty evidence) and for alopecia (RR 1.28, 95% CI 1.07 to 1.53; 1 RCT, 17448 participants; high-certainty evidence).
Who: healthy men in a randomized trial of selenium supplementation for cancer prevention
Effect: alopecia RR 1.28 (95% CI 1.07 to 1.53); grade 1 to 2 dermatitis RR 1.16 (1.04 to 1.31); 1 RCT, high certainty
Certainty: Single trial (SELECT, 200 mcg/day selenomethionine); men only.
Cochrane Database Syst Rev, 2020 · checked 2026-10-07 · we read the abstract
ev-sehl-02 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 19715
Other adverse effects that increased with selenium supplementation, as reported in the SELECT trial, included alopecia (RR 1.28, 95% CI 1.01 to 1.62) and dermatitis grade 1 to 2 (RR 1.17, 95% CI 1.0 to 1.35).
Who: adults in randomized trials of selenium-only supplementation vs placebo
Effect: alopecia RR 1.28 (95% CI 1.01 to 1.62); dermatitis grade 1 to 2 RR 1.17 (1.0 to 1.35)
Certainty: Alopecia data come from SELECT alone; no trial reports hair gain with selenium.
Cochrane Database Syst Rev, 2013 · checked 2026-10-07 · we read the abstract
ev-sehl-03 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials and cohorts · n = 27232
In the largest trial, the Selenium and Vitamin E Cancer Trial, selenium supplementation increased risks of alopecia and dermatitis, and for participants with highest background selenium status, supplementation also increased risk of high-grade prostate cancer.
Who: adults in randomized trials of selenium vs placebo, 88% men
Effect: increased risks of alopecia and dermatitis in SELECT; no cancer benefit (any cancer RR 1.01, 0.93 to 1.10)
Certainty: Hair outcome not pooled; reported from SELECT.
Cochrane Database Syst Rev, 2018 · checked 2026-10-07 · we read the abstract
ev-sehl-04 · Randomized controlled trial(s) · systematic review of randomized and non-randomized clinical studies · n = 30 studies (17 RCTs)
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: potential benefit for several multi-ingredient products, zinc, tocotrienol, pumpkin seed oil and others; no selenium-only intervention listed
Certainty: Several listed multi-ingredient products contain selenium, so its own role cannot be separated. no_pmc.
JAMA Dermatol, 2023 · checked 2026-10-07 · we read the abstract
ev-sehl-05 · Randomized controlled trial(s) · randomized assessor-blinded controlled trial · n = 83
At week 12 the GAS score in Group A was statistically significant higher in comparison with Group B (1.67 ± 0.16 and 0.66 ± 0.20, p < 0.001; Mann-Whitney test).
Who: adults with androgenetic alopecia or chronic telogen effluvium on specific drug treatment
Effect: global assessment score at week 12: 1.67 vs 0.66 (p < 0.001); score 2 or more in 50% vs 23%
Certainty: Multi-ingredient product, no placebo; selenium's share of any effect unknown.
Skin Res Technol, 2023 · checked 2026-10-07 · we read the abstract
ev-sehl-06 · Observational data · meta-analysis of case-control studies · n = 764
Overall, pooled analysis indicated that patients with AA had a lower serum level of zinc (P < 10-4 ) and selenium (P < 10-4 ) than the healthy controls.
Who: patients with alopecia areata and healthy controls
Effect: serum selenium lower in alopecia areata (P < 10-4); size not given in abstract
Certainty: Association only; low level could be a result, not a cause. Contradicted by ev-sehl-07.
J Dermatol, 2017 · checked 2026-10-07 · we read the abstract
ev-sehl-07 · Observational data · systematic review and meta-analysis of observational studies · n = 1315 patients and 7181 controls (all skin diseases)
Compared with controls, no significant difference in selenium was found in patients with vitiligo (SMD = 0.53, 95% CI: -0.40 to 1.45), alopecia areata (SMD = 0.47, 95% CI: -2.72 and 3.65), or eczema (SMD = 0.12, 95% CI: -0.24 to 0.48).
Who: patients with skin diseases and healthy controls
Effect: alopecia areata SMD 0.47 (95% CI -2.72 to 3.65), not significant
Certainty: Very wide interval; observational data disagree across reviews.
J Trace Elem Med Biol, 2020 · checked 2026-10-07 · we read the abstract
ev-sehl-08 · Observational data · outbreak investigation with follow-up questionnaires · n = 201
Frequently reported symptoms included diarrhea (78%), fatigue (75%), hair loss (72%), joint pain (70%), nail discoloration or brittleness (61%), and nausea (58%).
Who: people in 10 US states who took a misformulated liquid dietary supplement
Effect: hair loss 72%; still present at 90 days in 29%; median dose about 41,749 mcg/day
Certainty: Massive overdose; shows the hair-loss signature of selenosis.
Arch Intern Med, 2010 · checked 2026-10-07 · we read the abstract
ev-sehl-09 · Observational data · case series · n = 248
The most common sign of the poisoning was loss of hair and nails.
Who: inhabitants of high-selenium villages, Enshi County, Hubei; intakes about 5 mg/day
Effect: morbidity almost 50% in five villages; loss of hair and nails most common sign
Certainty: Historical environmental exposure; dietary intake far above supplement doses.
Am J Clin Nutr, 1983 · checked 2026-10-07 · we read the abstract
ev-sehl-10 · Position of an expert body · agency fact sheet · n = —
The Tolerable Upper Intake Level for selenium is 400 mcg for adults, and it ranges from 45 mcg to 400 mcg for infants, children, and adolescents, depending on age.
Who: adults and children
Effect: UL 400 mcg/day adults; 45 to 400 mcg for infants, children and adolescents by age
Certainty: T2; UL itself is based on hair and nail loss.
NIH Office of Dietary Supplements, Selenium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-sehl-11 · Position of an expert body · agency fact sheet · n = —
As discussed earlier, Brazil nuts contain very high amounts of selenium (68–91 mcg per nut) and could cause selenium toxicity if consumed regularly.
Who: people eating Brazil nuts regularly
Effect: 68 to 91 mcg selenium per nut
Certainty: T2; a few nuts a day exceed the RDA of 55 mcg.
NIH Office of Dietary Supplements, Selenium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-sehl-12 · Observational data · scoping review for dietary reference values · n = —
At high intakes above 330 to 450 µg/day selenium may cause toxic effects affecting liver, peripheral nerves, skin, nails, and hair.
Who: adults
Effect: toxicity above 330 to 450 mcg/day; EFSA UL 255 mcg/day
Certainty: EFSA limit is lower than the US 400 mcg; divergence between bodies.
Food Nutr Res, 2023 · checked 2026-10-07 · we read the abstract
ev-sehl-13 · Position of an expert body · EU register entry · n = —
POL-HC-6461 Selenium Selenium contributes to the maintenance of normal hair Authorised
Who: EU food labeling
Effect: claim authorized
Certainty: Generic function claim tied to adequate intake; not evidence that extra selenium treats hair loss.
EU Register on nutrition and health claims, claim POL-HC-6461, snapshot 2026-09-21 · checked 2026-10-07 · we read the section

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.