Does magnesium help with hair loss?

There is no evidence that it does. Only one randomized trial has given magnesium on its own and measured hair. It enrolled 64 women with polycystic ovary syndrome, gave 250 mg of magnesium oxide a day or a placebo for 10 weeks, and found no significant effect on hair loss. We found no systematic review or meta-analysis of magnesium for any kind of hair loss, and no trial registered to test it.

Unsettled. The answer is thin because almost nobody has asked the question. One small, short trial in one kind of hair loss, the androgen-driven thinning of PCOS, came back negative. Nobody has tested magnesium in telogen effluvium, in alopecia areata, in pattern hair loss in men, or in people who are actually short of magnesium. So the honest position is that magnesium has not been shown to help, and the one test it was given, it failed.

What the trials found

The one trial with a hair outcome

The trial recruited 64 women with PCOS and gave each a 250 mg magnesium oxide tablet after breakfast or a starch placebo for 10 weeks. Hair loss was graded on the Sinclair scale. The authors write that magnesium had no significant effect on alopecia. Acne and abnormal bleeding did not change either. We read the full text. The trial was small and short, and the magnesium group started with higher blood magnesium than the placebo group, which makes any comparison harder to read.

The same trial did find one thing. Total quality of life scores, reported by the women themselves on a questionnaire, improved against placebo (p below 0.001). The abstract does not say whether the women knew what they were taking. That result is about how the women felt overall. It says nothing about hair.

Is low magnesium behind hair loss?

Observational data say probably not. A meta-analysis of 10 case-control studies with 764 people compared blood levels of minerals in people with alopecia areata and in healthy controls. Zinc and selenium were lower in alopecia areata. Magnesium did not differ significantly (P = 0.07), and the abstract does not say in which direction the small gap ran. A separate study of 50 people with alopecia areata and 50 matched controls found magnesium was not altered, while zinc was lower in extensive, long-lasting disease. Blood magnesium is a poor marker of what the body holds, which limits both studies.

For diffuse hair loss, a case-control study of adults that recorded what they ate over three days looked at 13 nutrients. Only protein intake was linked to hair loss, with an odds ratio of 1.5 (1.06 to 2.3). Magnesium was not. This is a small study based on food records, and we read only the English abstract of a French paper.

None of this shows that magnesium could not matter in someone who is truly deficient. It shows that the people who were studied did not have a magnesium problem that tracked with their hair.

Who should be careful

Percent of trial participants with side effects, mostly digestive such as diarrhea

The review reports a range across trials, so the chart shows both ends of it. These trials were about muscle cramps in older adults, pregnancy and cirrhosis, not about hair. They are here because they show what oral magnesium does to the gut. The review gives no interval for these shares, so none is drawn. Source: card ev-mghl-01 below.

Magnesium tablets are not free of cost to the body. A Cochrane review of 11 randomized trials with 735 people, all about muscle cramps rather than hair, found side effects were mostly digestive, such as diarrhea. They hit between 11 and 37 percent of people on magnesium, against 10 to 14 percent on control. For minor side effects the risk ratio was 1.51, with an interval from 0.98 to 2.33 that just crosses no difference, on low-certainty evidence.

Not for everyone. Three groups should not treat magnesium as a harmless hair supplement. People with reduced kidney function or kidney failure, because the kidneys lose the ability to clear the excess and the risk of toxicity rises. People on oral bisphosphonates, tetracyclines or quinolone antibiotics, because magnesium interacts with them. The approved doxycycline label says antacids containing magnesium impair absorption of tetracyclines. People on diuretics or proton pump inhibitors, because those medicines change magnesium status, which is a reason to have it measured rather than guessed.

What expert bodies say

The NIH Office of Dietary Supplements sets the upper limit for supplemental magnesium at 350 mg a day for adults, and between 65 and 350 mg for children and adolescents depending on age. The limit covers supplements and medicines, not magnesium in food.

The EU register of authorized health claims holds no hair claim for magnesium. The claim a magnesium product may make is that magnesium contributes to normal protein synthesis. That general sentence often appears on hair supplements, and it says nothing about hair loss. We found no position from a dermatology body on magnesium for hair.

How we searched

Searched: a local copy of the PubMed baseline, all study types, for magnesium with hair loss, alopecia, telogen effluvium and androgenetic alopecia. We also searched reviews of micronutrients in hair loss, magnesium trials in PCOS, and safety reviews of oral magnesium. A broad first query returned 333 records, almost all using hair as a test material for mineral exposure. A narrower query returned 8, of which 4 were relevant. We also searched ClinicalTrials.gov, which held no registered trial, the NIH magnesium fact sheet, drug labels, the EU claims register and the open web. Search run on 7 October 2026.

Included: eight sources. One Cochrane review used only for side effects, one randomized trial, one meta-analysis and two case-control studies of observational data, the NIH fact sheet, the doxycycline label and the EU register.

Excluded: a 2024 meta-analysis of trace elements in alopecia areata that did not pool magnesium. Reviews of supplements for pattern hair loss with no magnesium arm. A trial of a multi-ingredient supplement in telogen effluvium, where the effect of magnesium cannot be separated. Magnesium trials in PCOS with no hair outcome. A report of hair loss from the drug magnesium valproate, which is an effect of the drug. Commercial blogs.

What we read: the full text of the PCOS trial, including its methods for grading hair loss, and the full text of the 2024 review to confirm it did not pool magnesium. Abstracts for the rest, with each quotation checked against the source.

What we could not get: the full text of the 2017 meta-analysis, so the size and direction of the magnesium difference are unknown. A Turkish study of telogen effluvium that reported how often people were short of magnesium, whose summary page no longer loads and which has no PubMed record. A 1976 paper on the magnesium content of hair in alopecia areata, available only as a paywalled abstract page.

What would change this answer

A randomized trial in people with documented low magnesium and hair loss, with hair counts or shedding as the outcome. That is the one group where a supplement could plausibly matter, and nobody has tested it.
Trials of magnesium alone in telogen effluvium, alopecia areata or pattern hair loss in men. We found none, published or registered.
The full results of the 2017 meta-analysis. If magnesium ran lower in alopecia areata and the gap was only just short of significance, a larger pooled study could change the observational picture.

The nutrients with more data in hair loss have their own pages: zinc, iron and protein. What magnesium does do, and how much you need, is in the magnesium guide. Whether it helps sleep is on its own evidence page.

The rest of the nutrient, in one place. Magnesium: widely under-eaten, and widely over-promised → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The full guide

Magnesium: widely under-eaten, and widely over-promised

The same question for other foods (hair loss)

Sources

ev-mghl-01 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of RCTs · n = 735
Overall, oral magnesium was associated with mostly gastrointestinal adverse events (e.g. diarrhoea), experienced by 11% (10% in control) to 37% (14% in control) of participants.
Who: people with skeletal muscle cramps in randomized trials of magnesium supplements (older adults, pregnancy, cirrhosis)
Effect: minor adverse events RR 1.51 (95% CI 0.98 to 2.33; 4 studies, 254 participants; low certainty); major adverse events 2/72 vs 3/68
Certainty: Trials were about cramps, not hair; the safety data apply to oral magnesium supplements in general.
Cochrane Database Syst Rev, 2020 · checked 2026-10-07 · we read the abstract
ev-mghl-02 · Randomized controlled trial(s) · parallel randomized placebo-controlled trial (IRCT20130903014551N9) · n = 64
We found that magnesium supplementation had no significant effect on alopecia.
Who: women with polycystic ovary syndrome; 250 mg magnesium oxide tablet per day after breakfast or starch placebo, 10 weeks; alopecia graded by the Sinclair Scale
Effect: no significant difference in alopecia (Sinclair stage) vs placebo at 10 weeks
Certainty: The only trial of magnesium alone with a hair outcome; small, short, androgen-related hair loss in PCOS only; baseline serum magnesium higher in the magnesium group.
Reprod Biol Endocrinol, 2022 · checked 2026-10-07 · we read the fulltext
ev-mghl-03 · Randomized controlled trial(s) · parallel randomized placebo-controlled trial · n = 64
Magnesium supplementation in women with PCOS had a significant positive effect on improving total quality of life.
Who: women with polycystic ovary syndrome, 250 mg magnesium oxide per day or placebo for 10 weeks
Effect: total quality of life p < 0.001 vs placebo; no significant effect on acne, alopecia or abnormal uterine bleeding
Certainty: Quality of life is self-reported (SF-36 style questionnaire); blinding not stated in the abstract.
Reprod Biol Endocrinol, 2022 · checked 2026-10-07 · we read the abstract
ev-mghl-04 · Observational data · meta-analysis of case-control 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 in case-control studies
Effect: serum magnesium P = 0.07 (not significant); serum zinc and selenium lower in alopecia areata (P < 10-4)
Certainty: Association only; direction and size of the magnesium difference not given in the abstract; no_pmc.
J Dermatol, 2017 · checked 2026-10-07 · we read the abstract
ev-mghl-05 · Observational data · comparative case-control study · n = 100
We conclude that copper and magnesium levels are not altered in AA, but the decreased zinc levels found in our study may merit further investigation of the relationship.
Who: 50 alopecia areata patients (34 men, 16 women) and 50 age and sex matched healthy controls
Effect: serum magnesium and copper showed an insignificant rise vs controls; zinc significantly lower in extensive, prolonged, treatment-resistant AA
Certainty: Single small study; serum magnesium is a poor marker of body stores.
Indian J Dermatol Venereol Leprol, 2009 · checked 2026-10-07 · we read the abstract
ev-mghl-06 · Observational data · cross-sectional case-control study · n = 272
On multivariate analysis, only a protein intake was directly associated to alopecia, odds ratio of 1,5 (1,06 - 2,3) p=0,02.
Who: adults aged 20 to 35 with diffuse alopecia and matched controls without hair disorders; 3-day food records of 13 nutrients including magnesium
Effect: protein intake OR 1.5 (1.06 to 2.3), p = 0.02; no other nutrient, magnesium included, retained in multivariate analysis
Certainty: Small; dietary recall; article in French with English abstract, full text not read.
Rev Med Liege, 2010 · checked 2026-10-07 · we read the abstract
ev-mghl-07 · Position of an expert body · government fact sheet · n = —
The Tolerable Upper Intake Level for supplemental magnesium is 350 mg for adults, and it ranges from 65 to 350 mg for children and adolescents, depending on age.
Who: healthy adults and children; UL covers supplements and medicines, not food
Effect: UL 350 mg/day supplemental magnesium for adults; 65 to 350 mg for children and adolescents
NIH Office of Dietary Supplements, Magnesium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-mghl-08 · Position of an expert body · government fact sheet · n = —
The risk of magnesium toxicity increases with impaired renal function or kidney failure because the ability to remove excess magnesium is reduced or lost [1,29].
Who: people with impaired renal function or kidney failure
Effect: reduced or lost ability to remove excess magnesium; toxicity signs usually above serum 1.74 to 2.61 mmol/L
NIH Office of Dietary Supplements, Magnesium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-mghl-09 · Position of an expert body · government fact sheet · n = —
Magnesium may interact with certain medications, such as oral bisphosphonates, tetracyclines, and quinolone antibiotics.
Who: people taking these medicines regularly
Effect: interactions with bisphosphonates, tetracyclines, quinolones; diuretics and PPIs affect magnesium status
NIH Office of Dietary Supplements, Magnesium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-mghl-10 · Position of an expert body · FDA-approved drug label, drug interactions section · n = —
Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations.
Who: people taking doxycycline or other tetracyclines
Effect: reduced antibiotic absorption when taken with magnesium-containing antacids
Certainty: Label text; spacing doses apart is the usual advice.
Doxycycline, FDA-approved label (DailyMed), effective 2026-05-01 · checked 2026-10-07 · we read the section
ev-mghl-11 · Position of an expert body · EU Register on nutrition and health claims, claim POL-HC-6406, snapshot of 2026-09-21 · n = —
POL-HC-6406 Magnesium Magnesium contributes to normal protein synthesis Authorised
Who: foods and supplements sold in the EU
Effect: claim status: Authorized; no magnesium hair claim in the register
Certainty: Generic role claim, often used in hair supplement marketing; it says nothing about hair loss.
EU Register on nutrition and health claims, claim POL-HC-6406, 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.