Collagen has become one of the more talked-about hair supplements in recent years, and unlike some hair growth trends, there's a genuinely newer and more active body of research behind it, though it comes with real caveats worth understanding. This guide covers what the current evidence actually shows, how collagen compares to other supplements like biotin, and what to know about choosing a type.

What Is Collagen and Why Is It Linked to Hair?

Collagen is the most abundant structural protein in the body, found in skin, bone, tendons, and connective tissue, including structures involved in the hair follicle. Collagen production naturally declines with age, similar to changes seen in skin. It's worth being precise about the mechanism here: hair itself is made primarily of keratin, not collagen, but when collagen is digested, it breaks down into amino acids and smaller peptides that the body can use as building blocks for various proteins, potentially including those involved in hair growth. This is a more indirect relationship than marketing sometimes implies, where collagen is often described as if it's delivered directly to hair follicles intact.

Does Collagen Help Hair Growth?

The evidence here is more mixed and more actively evolving than for many hair supplements, so it's worth unpacking carefully. Laboratory research using human hair follicle organ culture, a model that studies real hair follicle tissue outside the body, has found that hydrolyzed collagen peptides can influence hair follicle stem cell activity and inhibit the follicle's transition into its resting phase, suggesting a plausible biological mechanism. More recent human clinical trials have also shown promising results: a 2023 randomized, controlled study found a supplement containing marine hydrolyzed collagen, along with amino acids, iron, and selenium, improved hair growth measures in people with androgenetic alopecia, female pattern hair loss, or telogen effluvium. A separate 2024 randomized, placebo-controlled trial found a hydrolyzed collagen supplement, combined with vitamin C, improved scalp and hair condition alongside skin measures over 12 weeks.

The important caveat: both of these trials tested combination products containing collagen alongside other active ingredients, not collagen in isolation, so it isn't possible to say from this research how much of the benefit came from collagen specifically versus the other included ingredients. Both studies were also sponsor-funded, evaluating a specific branded product, which is a common limitation across supplement research generally and worth factoring into how much weight to give the results.

Which Type of Collagen Is Best for Hair?

Most of the research on collagen and hair has used hydrolyzed collagen, meaning it's been broken down into smaller peptides that are more easily absorbed than intact collagen protein, generally sourced from marine (fish) or bovine sources and predominantly Type I collagen. Laboratory research comparing marine and bovine-derived collagen peptides found they had somewhat different effects on distinct hair follicle stem cell populations, which is scientifically interesting but hasn't yet been translated into clear evidence that one source is definitively better for hair in real-world human use. Beyond choosing a hydrolyzed (rather than non-hydrolyzed) form, there currently isn't strong comparative human evidence establishing one specific type or source as clearly best.

Collagen for Skin Versus Hair

Collagen's evidence base is considerably more established for skin than for hair specifically. Clinical trials have shown more consistent improvements in skin elasticity, hydration, and roughness with hydrolyzed collagen supplementation than the newer, more limited research on hair. If you're considering collagen primarily for hair, it's worth knowing that the research supporting its skin benefits is currently stronger and more extensively replicated.

How Does Collagen Compare to Biotin?

It's worth being fair to the actual evidence rather than lumping every hair supplement into the same category. Our related guide on biotin for hair growth covers research showing the highest-quality available study found no significant difference between biotin and a placebo in people without a deficiency. Collagen's evidence, by contrast, includes newer randomized controlled trials showing some promising results, even though those trials involved combination products and industry funding that limit how confidently the results can be generalized. Neither supplement currently has evidence approaching the strength behind FDA-approved treatments like topical minoxidil, but it's inaccurate to say the evidence is identical for both.

Practical Considerations Before Trying Collagen

• Most studied products combine collagen with other ingredients like vitamin C, amino acids, iron, or selenium, so a single-ingredient collagen product hasn't been tested in the same way as the combination formulas used in these trials.
• Studies generally used the supplement for eight to twelve weeks before evaluating results, so a similar timeframe is reasonable before judging whether it's helping.
• Collagen supplements aren't a substitute for evidence-based treatment of a diagnosed hair loss condition like androgenetic alopecia or alopecia areata.
• If you're pregnant, breastfeeding, or taking other medications or supplements, it's worth checking with a healthcare provider before adding a new supplement.

What Has Stronger Evidence for Hair Growth?

If you're dealing with noticeable hair thinning, treatments with a larger, more established body of evidence are generally a better starting point. Our related guide on minoxidil for men and our guide on baldness cover FDA-approved options with substantially more research behind them than any current hair supplement, and our guide on the best shampoo for hair loss covers topical ingredients with real supporting evidence.

When Should You See a Healthcare Professional?

If hair thinning is your main concern, it's worth getting an accurate diagnosis from a dermatologist before relying on a supplement, since the underlying cause affects which treatments are actually likely to help. A healthcare provider can also help you weigh whether a collagen supplement makes sense alongside any treatments you're already using.

Frequently Asked Questions

Does collagen help hair growth?

The evidence is more promising and more actively developing than for some other hair supplements, with recent randomized controlled trials showing improvements in hair measures using collagen-containing combination products, alongside laboratory research suggesting a plausible biological mechanism. That said, these trials tested collagen combined with other active ingredients rather than collagen alone, and were funded by the product's manufacturer, so the evidence, while more encouraging than for some supplements, is still preliminary compared to established, FDA-approved treatments.

Which type of collagen is best for hair?

Most research uses hydrolyzed (broken down into peptides) Type I collagen, generally sourced from marine or bovine origins, since hydrolyzed forms are more readily absorbed than intact collagen protein. Laboratory research has found some differences between marine and bovine-derived collagen peptides in how they affect hair follicle cells, but this hasn't yet translated into clear evidence that one source works better than the other in real-world use. Beyond choosing a hydrolyzed form, there isn't strong comparative evidence pointing to one specific type as definitively best.

Conclusion

Collagen's evidence for hair growth is genuinely more promising and more actively researched than some other popular hair supplements, with newer randomized controlled trials showing encouraging results, though those trials tested combination products with industry funding, which limits how much can be concluded about collagen specifically. It remains considerably better established for skin than for hair. If you're dealing with noticeable hair loss, treatments with a larger evidence base, like topical minoxidil, are a more reliable starting point, and a dermatologist can help you weigh whether a collagen supplement is worth adding alongside them.

Doc Med Center provides health information for general educational purposes only. This content is not a substitute for professional medical advice, diagnosis, or treatment. Speak with a qualified healthcare professional about your individual health concerns.

References

Milani M, et al. — Efficacy and Tolerability of an Oral Supplement Containing Amino Acids, Iron, Selenium, and Marine Hydrolyzed Collagen in Subjects with Hair Loss (Skin Research and Technology, 2023): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10240182/

Reilly D, et al. — A Clinical Trial Shows Improvement in Skin Collagen, Hydration, Elasticity, Wrinkles, Scalp, and Hair Condition Following 12-Week Oral Intake of a Supplement Containing Hydrolysed Collagen (Dermatology Research and Practice, 2024): https://onlinelibrary.wiley.com/doi/10.1155/2024/8752787

ScienceDirect — Revealing Novel Insights on How Oral Supplementation with Collagen Peptides May Prevent Hair Loss: Lessons from the Human Hair Follicle Organ Culture: https://www.sciencedirect.com/science/article/pii/S1756464624001269

Almohanna HM, et al. — The Role of Vitamins and Minerals in Hair Loss: A Review (Dermatology and Therapy, 2019): https://doi.org/10.1007/s13555-018-0278-6