🟢 Strong Evidence
A randomized controlled trial published in the Journal of the International Society of Sports Nutrition (2025) has directly tested and refuted a persistent claim that creatine supplementation causes hair loss—a concern based on a single small study from 2009 that never actually measured hair.
Key takeaways
- A 2009 study of 20 rugby players showing elevated DHT levels spawned 16 years of hair-loss claims without clinical evidence
- The new RCT measured actual hair outcomes: no change in density, follicle count, or thickness after 12 weeks of creatine
- No changes in DHT or testosterone were observed, contradicting even the hormonal basis of the original concern
Study at a Glance
| Source | Journal of the International Society of Sports Nutrition |
| Study type | Randomized controlled trial, double-blind |
| Sample size | N = 38 resistance-trained males |
| Intervention | 5 g/day creatine monohydrate vs placebo for 12 weeks |
| Outcomes measured | Hair density, follicular unit count, cumulative hair thickness, DHT, testosterone |
From Extrapolation to Evidence: The Journey of the Creatine Myth
Timeline of the claim’s origin and first direct clinical test
Sources: Van der Merwe et al., Clin J Sport Med, 2009; Lak et al., JISSN, 2025 | Georgian Medical Journal News
The Original Study: Hormone Marker, Not Clinical Outcome
In 2009, van der Merwe and colleagues published a study in the Clinical Journal of Sport Medicine examining 20 rugby players who supplemented with creatine. The research found a statistically significant elevation in dihydrotestosterone (DHT), a hormone implicated in androgenetic alopecia (male pattern baldness).
However, the 2009 study measured only hormonal markers—not a single hair outcome. No hair density was assessed. No follicle counts were performed. No clinical measure of hair loss was recorded. The leap from elevated DHT to actual hair loss was never tested empirically, yet it became the foundation of widespread concern.
The 2025 RCT: Direct Measurement of Hair
Researchers led by Lak and colleagues conducted the first rigorous trial to directly assess whether creatine affects hair. According to the Journal of the International Society of Sports Nutrition (2025), 38 resistance-trained males were randomized to receive either 5 grams per day of creatine monohydrate or placebo in a double-blind design for 12 weeks.
The study measured multiple hair parameters: hair density, follicular unit count, and cumulative hair thickness. It also reassessed DHT and testosterone levels. The results were unambiguous: no statistically significant changes in any measure of hair growth or structure. DHT levels did not rise. Testosterone remained stable. Hair density was unchanged.
No change in hair density, follicular unit count, cumulative hair thickness, DHT, or testosterone after 12 weeks of 5 g/day creatine monohydrate versus placebo in 38 resistance-trained males.
— Lak et al., Journal of the International Society of Sports Nutrition (2025)
Why the Myth Persisted: Evidence Gaps in Sports Nutrition
This case exemplifies how a single finding—even a statistically significant one—can propagate into public health belief without direct clinical validation. The 2009 study was small (N=20), measured only a mechanistic proxy (DHT), and was never replicated before spawning 16 years of consumer warnings.
Athletes, fitness enthusiasts, and clinicians seeking evidence-based guidance have faced contradictory signals: biochemical plausibility (elevated DHT could theoretically trigger hair loss) versus absent clinical evidence (no one had actually tested it on hair). The new RCT published in 2025 closes that gap, shifting the evidence base from inference to direct measurement.
Implications for Supplement Users and Clinicians
For resistance-trained men concerned about hair loss, the evidence now suggests that creatine monohydrate supplementation at standard doses (5 g/day) does not cause measurable changes in hair parameters or the hormonal markers previously implicated. This does not mean individual susceptibility is impossible, but it means the population-level risk—if it exists—is not detectable in a 12-week trial.
The study also highlights the importance of distinguishing mechanistic biomarkers from clinical outcomes in supplement safety. Elevated DHT alone is not evidence of hair loss, as the 2009 study assumed. Direct measurement of the alleged harm—in this case, hair density—is essential before cautionary claims are broadcast.
What this means
Frequently asked questions
Was the 2009 study flawed?
No—the 2009 study by van der Merwe et al. was methodologically sound within its scope. It correctly measured DHT elevation in 20 rugby players. The flaw was not the study itself but the unsupported extrapolation to clinical hair loss without ever testing hair outcomes. This highlights the importance of replication and direct outcome measurement.
Could creatine still cause hair loss in some people?
The Lak et al. trial found no population-level effect in 38 men over 12 weeks. Individual susceptibility cannot be ruled out with absolute certainty, but the burden of evidence now requires demonstration rather than hypothesis. If someone experiences hair loss while using creatine, other causes (genetic predisposition, age, stress) are more likely.
Is creatine monohydrate safe for long-term use?
This trial examined 12 weeks of use. Creatine has a long safety track record in sports nutrition research spanning decades, but this specific study does not address outcomes beyond 12 weeks. Individuals with pre-existing kidney disease should consult a clinician before supplementing.
The resolution of the creatine–hair loss controversy demonstrates the self-correcting power of rigorous clinical research. After 16 years of uncertainty rooted in a single hormone study, a double-blind RCT measuring actual hair outcomes has provided clarity. As evidence-based medicine advances, supplement safety claims will increasingly require direct clinical validation rather than mechanistic inference alone. This standard protects consumers and ensures that public health guidance reflects what we have actually measured, not merely what we theoretically expect.
Sources: Van der Merwe et al., Clinical Journal of Sport Medicine, 2009; Lak et al., Journal of the International Society of Sports Nutrition, 2025
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