Do collagen supplements help hair growth and skin?

For hair, nobody has shown it. We found no systematic review that tests collagen on its own for hair loss. One randomized trial in 114 women aged 20 to 50 with self-reported thinning found that 1 g a day of a fish collagen peptide for 24 weeks made hair strands thicker than placebo, and it did not measure shedding or hair counts. For skin, trials look positive when pooled. A meta-analysis of 23 randomized trials with 1,474 people found that the benefit to hydration, elasticity and wrinkles appeared only in industry-funded trials and vanished in independent and high-quality ones.

Unsettled. The hair question has barely been asked. One trial of one proprietary peptide measured strand thickness, and the abstract does not say by how much. Another trial used a tablet with iron and selenium in it. The reviews of hair supplements pool branded blends, none of them plain collagen. That is too little to say collagen helps hair, and too little to say it does not.

Percent of patients whose global hair score rose by 2 points or more in 12 weeks

The tablet held 300 mg of collagen together with amino acids, iron and selenium, so the gap cannot be credited to collagen. Assessors were blinded and there was no placebo. The paper gives no interval for these shares, so none is drawn. Source: card ev-colh-06 below.

What the trials found

Hair

The fish peptide trial recruited women aged 20 to 50 who had thigh cellulite and reported thinning hair, and gave 1000 mg a day of a low-molecular-weight fish collagen peptide or placebo. At week 24 hair diameter had risen significantly, and more women on the peptide showed measurable thickening. The size of the change is not in the abstract, and we could not get the full text. Hair loss itself was not an outcome.

The second trial ran in 83 adults, mean age 41, with pattern hair loss or chronic telogen effluvium, the diffuse shedding that follows illness or stress. All stayed on their drug treatment, and half added a daily tablet with 300 mg of collagen plus amino acids, iron and selenium. After 12 weeks the global hair score was 1.67 in the tablet group against 0.66 in the others, and half of the tablet group improved by 2 points or more, against 23 percent. The assessors were blinded. There was no placebo, and the iron in the tablet makes it impossible to tell what collagen added.

A 2026 meta-analysis of 14 hair supplement studies with 967 people found more growing hairs with branded supplements (mean difference 10.48, 95% CI 8.81 to 12.14) and fewer resting hairs. Total hair count did not change significantly. The products were multi-ingredient blends, mostly industry-funded, and none was plain collagen, so this result says nothing about collagen on its own.

Skin

This is where most of the trials are, and they disagree with themselves. Pooling 19 double-blind trials in 1,125 mostly female adults, about 90 days of hydrolyzed collagen improved hydration, elasticity and wrinkles against placebo. That meta-analysis did not split trials by who paid for them.

Pooled effect of collagen on skin, as standardized mean differences against placebo

A standardized difference has no unit, so the bars compare size across outcomes rather than measure skin. The risk of bias in these trials was unclear and publication bias was not assessed. A larger meta-analysis that split trials by funding found no effect in the independent ones. Sources: cards clgn-daily-r4-06 and ev-colh-01 below.

The 23-trial meta-analysis did, and that split is the answer for skin. Trials funded by supplement companies showed significant effects. Trials without that funding, and trials rated high quality, showed none. A 2025 review of 40 randomized trials of supplements for sun-aged skin still found collagen raised elasticity against placebo, in trials mostly 24 weeks or shorter, and its abstract gives no effect size. One example of the positive trials: in 85 East Asian women aged 43 to 65, 5 g a day of collagen peptides for 84 days improved dermis density and skin moisture against placebo. Both groups used the same face cream, the product came from industry, and hair was not measured.

Unsettled. Collagen is not proven to improve skin. The pooled numbers look convincing, but in the meta-analysis that split trials by funding, the effect showed up only in trials paid for by the companies that sell it. Independent and high-quality trials found none. That is the most useful finding on this page.

Nails

In an open-label trial of 25 people with brittle nails, 2.5 g a day of collagen peptides for 24 weeks raised nail growth by 12 percent and cut broken nails by 42 percent. There was no placebo, so part of that could be time or expectation.

Who should be careful

In the trials, collagen looks harmless. A review of 11 placebo-controlled trials with 805 people, at 2.5 to 10 g a day for 8 to 24 weeks, found no reported adverse events. The trials were small and short and often did not actively collect side effects. A wider review of 25 trials also found few side effects, and most of those trials carried a high risk of bias. Neither covers long-term use.

Not for everyone. Two groups have a specific reason for caution. In 10 healthy adults, 30 g a day of gelatin for five days raised urinary oxalate by 43 percent against whey protein, in a small, short study that did not measure stones. Changes showed up at 5 and 10 g loads and not at 1 or 2 g, and usual collagen doses of 2.5 to 10 g overlap that range. If you have had kidney stones, that is worth raising with your doctor before a daily habit. Gelatin allergy is rare and can be severe. One case report describes anaphylaxis within 5 minutes of a gelatin capsule in a 20-year-old woman with gelatin-specific antibodies.

We have no card on collagen in pregnancy, in children or alongside 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 EU has not authorized the two collagen skin claims we checked. It refused the general claim that collagen helps skin keep its firmness and elasticity, and refused the claim for a branded collagen peptide mixture said to raise skin elasticity and reduce wrinkles. Non-authorized means the evidence did not meet the bar when it was assessed. There is no collagen claim about hair in the EU register at all. We found no dermatology body position on collagen and hair loss.

How we searched

Searched: a local copy of PubMed, queried on 6 October 2026 for collagen, collagen peptides, hydrolyzed collagen or gelatin with hair, alopecia, hair loss, hair growth, nails or skin (248 hits, mostly skin, with two hair trials). A narrower hair and nail query gave 26 hits. Further queries covered meta-analyses of hair supplements (4 hits, none with a collagen-only arm), gelatin and urinary oxalate, and allergy to oral collagen or gelatin. We searched the full texts of the two hair supplement reviews for any collagen-only product, the EU register of health claims (22 collagen entries, none about hair), ClinicalTrials.gov (one unpublished trial of a salmon protein hydrolysate with hair as a secondary self-rated outcome), the web for newer reviews, and Retraction Watch for every source used. None was retracted.

Included: four meta-analyses or systematic reviews, three of them limited to randomized trials, three randomized trials, an open-label nail trial, a feeding study on oxalate, a case report and an EU register entry from this search, alongside skin, safety and EU claim cards already in our collagen set.

Excluded: a review of diet and skin aging that did not say whether all its studies were randomized. A network meta-analysis of supplements for pattern hair loss with no collagen arm. An uncontrolled study of a fish collagen blend that judged hair only by a satisfaction questionnaire. Single skin trials already inside the meta-analyses, a study in cats, and older allergy case reports.

What we read: abstracts, with each quotation checked against the abstract text, and the full texts of the two hair supplement reviews. For the oxalate study the quotation was read through Europe PMC and confirmed on the PubMed Central page.

What we could not get: the full text of the fish peptide trial, so the size of the hair diameter change is missing. A manufacturer study of collagen for hair thickness in women, found only in press releases with no PubMed record, which we did not treat as a source.

What would change this answer

An independent, placebo-controlled trial of plain collagen in people with hair loss, with hair counts or shedding as the outcome. We found none, in print or registered.
The full results of the fish peptide trial. If the gain in strand thickness is large and holds up in a second trial, the hair answer would move from untested to promising.
For skin, more trials without industry funding. The gap between funded and independent trials is the whole question, and only new independent trials can close it.

Iron, another ingredient in the tablet trial above, has its own evidence page on hair loss.

The food behind this question

Collagen supplements: the skin benefit fades when the sponsor leaves — numbers, evidence and safety

The same question for other foods (hair loss)

Sources

ev-colh-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs with funding and quality subgroups · n = 1,474
However, in the subgroup meta-analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements for improving skin hydration, elasticity, and wrinkles, while those receiving funding from pharmaceutical companies did show significant effects.
Who: adults in randomized trials of oral collagen for skin aging
Effect: pooled: hydration, elasticity and wrinkles improved; independent and high-quality trials: no significant effect
Certainty: Skin outcomes only; no hair outcomes pooled.
Am J Med, 2025 · checked 2026-10-06 · we read the abstract
ev-colh-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs, PROSPERO registered · n = 40 trials
Collagen, flavanols, and other polyphenol supplements have been found to alleviate skin photoaging and increase MED or overall skin elasticity (R2) when compared to a placebo.
Who: adults in randomized trials of oral supplements for skin photoaging
Effect: collagen improved skin elasticity (R2) or MED vs placebo; hyaluronic acid, lycopene and carotenoids did not
Certainty: Effect size for collagen not given in the abstract; trials mostly 24 weeks or shorter.
Front Med (Lausanne), 2025 · checked 2026-10-06 · we read the abstract
ev-colh-03 · Meta-analysis or systematic review · systematic review of randomized placebo-controlled trials · n = 805
Collagen supplementation is generally safe with no reported adverse events.
Who: randomized placebo-controlled trials of oral collagen in dermatology
Effect: no reported adverse events; skin elasticity, hydration and dermal collagen density improved
Certainty: Trials small and short; adverse events often not actively collected.
J Drugs Dermatol, 2019 · checked 2026-10-06 · we read the abstract
ev-colh-04 · Randomized controlled trial(s) · systematic review and meta-analysis of RCTs, open-label and proof-of-concept studies · n = 967
Supplements assessed included Ceramosides, Nutrafol, Nourkrin, Lambdapil, Viviscal, Forti5, GFM oral supplement, and Cynatine HNS.
Who: adults with alopecia or hair thinning taking commercial oral supplements
Effect: anagen hair density MD +10.48 (95% CI 8.81 to 12.14); telogen density MD -5.91 (-6.74 to -5.08); total hair count not significant (p = 0.06)
Certainty: Products were multi-ingredient (marine protein complexes, plant extracts); mostly industry-funded; says nothing about collagen alone.
J Cosmet Dermatol, 2026 · checked 2026-10-06 · we read the abstract
ev-colh-05 · Randomized controlled trial(s) · randomized placebo-controlled trial · n = 114
Hair diameter also increased significantly at week 24, with a larger proportion of participants in the LMWCP group exhibiting measurable hair thickening.
Who: women aged 20 to 50 with thigh cellulite and self-reported hair thinning; low-molecular-weight fish collagen peptide 1000 mg/day or placebo
Effect: hair diameter increased significantly at week 24 vs placebo; size of change not in the abstract
Certainty: Single trial of a proprietary peptide; hair loss (shedding, counts) not measured; no full text.
J Med Food, 2026 · checked 2026-10-06 · we read the abstract
ev-colh-06 · Randomized controlled trial(s) · randomized assessor-blinded controlled trial, add-on to drug treatment, no placebo · 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 drug treatment, mean age 41; 26 men, 57 women
Effect: GAS at 12 weeks 1.67 vs 0.66 (p < 0.001); GAS of 2 or more in 50% vs 23%
Certainty: Multi-ingredient tablet with iron, so the collagen effect cannot be separated; no placebo.
Skin Res Technol, 2023 · checked 2026-10-06 · we read the abstract
ev-colh-07 · Randomized controlled trial(s) · randomized placebo-controlled trial · n = 85
After 84 days, a significant improvement of dermis density and skin moisture was observed in the collagen peptides group compared to the placebo group.
Who: healthy women aged 43 to 65, standardized face cream in both groups; collagen peptides 5 g or maltodextrin
Effect: dermis density and skin moisture improved vs placebo at day 84; nail color improved earlier
Certainty: Hair not measured; industry product.
J Cosmet Dermatol, 2024 · checked 2026-10-06 · we read the abstract
ev-colh-08 · Observational data · open-label single-center trial, no control group · n = 25
Bioactive collagen peptides treatment promoted an increase of 12% nail growth rate and a decrease of 42% in the frequency of broken nails.
Who: participants with brittle nail syndrome, 2.5 g/day bioactive collagen peptides
Effect: nail growth rate +12%; frequency of broken nails -42%; 64% global clinical improvement
Certainty: No placebo; nails, not hair.
J Cosmet Dermatol, 2017 · checked 2026-10-06 · we read the abstract
ev-colh-09 · Observational data · controlled crossover feeding study, randomization not stated · n = 10
Urinary glycolate excretion was 5.3-fold higher on the gelatin diet compared to the whey diet and urinary oxalate excretion was 43% higher.
Who: healthy subjects with no history of nephrolithiasis, two 5-day controlled diets with 30 g gelatin or whey, washout of at least 1 week
Effect: urinary oxalate +43%, glycolate 5.3-fold vs whey; changes seen at 5 and 10 g loads, not at 1 and 2 g
Certainty: Small, short; healthy people; stone risk itself not measured. Typical collagen doses (2.5 to 10 g) overlap the loads that raised oxalate.
Kidney International, 2006, Hydroxyproline ingestion and urinary oxalate and glycolate excretion · checked 2026-10-06 · we read the abstract
ev-colh-10 · Laboratory or animal data · case report · n = 1
Allergic reactions to gelatin are comparatively rare, but according to the past reports, the reactions were severe.
Who: one 20-year-old woman with gelatin-specific IgE
Effect: anaphylaxis within 5 minutes of a gelatin-containing capsule; no reactions after avoiding gelatin
Certainty: Single case; frequency of collagen supplement allergy unknown.
Arerugi, 2014 · checked 2026-10-06 · we read the abstract
ev-colh-11 · Position of an expert body · EU Register on nutrition and health claims, claim POL-HC-8433, snapshot of 2026-09-21 · n = —
POL-HC-8433 VeriSol®P Characteristic collagen peptide mixture (collagen hydrolysate) having a beneficial physiological effect on the maintenance of skin health, as indicated by an increased skin elasticity and a reduction of wrinkles volume, by contributing to a normal collagen and elastin synthesis. -/- Non-authorised
Who: foods and supplements sold in the EU
Effect: claim status: non-authorized
Certainty: Non-authorized means the evidence did not meet the bar at assessment; no hair claim for collagen exists in the register.
EU Register on nutrition and health claims, claim POL-HC-8433, snapshot 2026-09-21 · checked 2026-10-06 · we read the section
clgn-daily-r4-05 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 1125
In the meta-analysis, a grouped analysis of studies showed favorable results of hydrolyzed collagen supplementation compared with placebo in terms of skin hydration, elasticity, and wrinkles.
Who: 19 RCTs, 1125 participants aged 20 to 70, 95% women
Effect: favorable vs placebo for hydration, elasticity and wrinkles; effect sizes not in the abstract
Certainty: no analysis by funding (see card 04)
Int J Dermatol, 2021 · checked 2026-10-03 · we read the abstract
clgn-daily-r4-06 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 646
The findings indicate that collagen supplements were statistically effective in increasing skin hydration (SMD 1.25 (CI: 0.77-1.74)) and elasticity (SMD 0.61 (CI: 0.21-1.02)). The most commonly administered dose was 4 g/day, with a median dose of 3.5 g/ day.
Who: 10 RCTs, 646 participants, mostly women, studies 2010 to 2021
Effect: hydration SMD 1.25 (95% CI 0.77 to 1.74); elasticity SMD 0.61 (0.21 to 1.02); most common dose 4 g/day, median 3.5 g/day
Certainty: risk of bias unclear; publication bias not assessed
Indian J Dermatol Venereol Leprol, 2025 · checked 2026-10-03 · we read the abstract
clgn-daily-r4-16 · Meta-analysis or systematic review · systematic review of RCTs, descriptive synthesis · n = —
HC supplementation was generally well-tolerated, with a low incidence of adverse events. ... The majority of included trials were rated as having a high risk of bias.
Who: 25 RCTs, 13 to 236 participants each, adults
Effect: low incidence of adverse events; majority of trials at high risk of bias
Certainty: no meta-analysis; no long-term safety
Eur J Clin Nutr, 2026 · checked 2026-10-03 · we read the abstract
clgn-daily-r4-19 · Position of an expert body · regulatory decision · n = —
POL-HC-8291 Collagen Collagen is a natural component of the skin. Helps the skin to preserve its firmness and elasticity. Has beneficial effect in the maintenance of skin firmness and elasticity. Non-authorised
Who: EU health claims register
Effect: status non-authorized
Certainty: reason for refusal is absent in the snapshot; EFSA opinion separately
EU Register on nutrition and health claims, claim POL-HC-8291, snapshot 2026-09-21 · checked 2026-10-03 · we read the dataset

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.