Creatine and Testosterone: What the Studies Actually Measured

The Claim That Launched a Thousand Headlines

Search for "creatine testosterone" and you will find fitness forums, supplement ads, and social media posts all pointing to the idea that creatine boosts testosterone. Some go further, claiming it raises dihydrotestosterone (DHT) and therefore accelerates hair loss. The source of nearly all of this is a single study published in 2009. Understanding what that study actually measured requires reading past the headlines.

The van der Merwe Study: Design and Findings

In 2009, van der Merwe and colleagues at Stellenbosch University in South Africa published a randomized, double-blind, placebo-controlled trial in the Clinical Journal of Sport Medicine. The study enrolled 20 college-age male rugby players. After a 7-day loading phase (25 g/day creatine monohydrate) followed by a 14-day maintenance phase (5 g/day), the researchers measured serum testosterone, DHT, and the DHT-to-testosterone ratio at baseline, after loading, and after maintenance.

Testosterone levels did not change significantly in the creatine group compared to placebo. DHT, however, increased by 56% after the loading phase and remained 40% above baseline after the maintenance phase. The DHT-to-testosterone ratio followed the same pattern, rising by 36% during loading and remaining 22% elevated during maintenance.

This is the only published study to date that has measured creatine's effect on DHT specifically. It has never been replicated.

Limitations Worth Noting

A sample size of 20 is small for hormonal research. Hormones fluctuate based on time of day, sleep quality, physical stress, and diet. The study controlled for some of these factors but could not eliminate all confounders in a three-week window with college athletes in active training.

The authors themselves noted the preliminary nature of their findings and called for further investigation. The magnitude of the DHT increase was statistically significant, but the clinical meaning of a 56% rise from baseline depends on where baseline sits. All participants remained within normal physiological ranges throughout the study. A shift within normal range is not equivalent to pathological elevation.

The study also did not examine downstream effects. No hair follicle assessments were performed. No prostate markers were tracked. The connection between elevated DHT and hair loss is well-established in androgenetic alopecia research, but the van der Merwe study did not measure or claim any such outcome.

What About Testosterone Itself?

The broader literature on creatine and total testosterone is more extensive, and the results are inconsistent. Volek and colleagues published an early study in 1997 examining creatine supplementation during a 12-week resistance training program. They found no significant difference in resting testosterone levels between creatine and placebo groups. They did observe that the creatine group showed greater increases in lean body mass and strength, but this was not mediated by changes in circulating testosterone.

A 2006 study by Hoffman and colleagues examined creatine supplementation in collegiate football players over 10 weeks of training. Again, no significant changes in testosterone, cortisol, or the testosterone-to-cortisol ratio were observed between groups.

Op't Eijnde and colleagues (2003) found no hormonal changes in a longer-term study involving older adults supplementing creatine during resistance training. Cooke and colleagues (2014) similarly reported that creatine did not alter testosterone, free testosterone, or cortisol in young men performing resistance exercise.

In a systematic review and meta-analysis, Delpino and colleagues (2022) evaluated the available randomized controlled trials on creatine and testosterone. Their analysis found no significant effect of creatine supplementation on total testosterone levels. The review included studies of varying durations, populations, and dosing protocols, and the overall conclusion was that creatine does not meaningfully alter testosterone concentrations.

DHT: Mechanism and Relevance

Dihydrotestosterone is synthesized from testosterone by the enzyme 5-alpha-reductase. It is a more potent androgen than testosterone at the androgen receptor and plays a role in prostate tissue growth, skin sebum production, and the miniaturization of hair follicles in genetically susceptible individuals. Elevated DHT is the primary hormonal driver of male pattern baldness.

The question is whether creatine supplementation exerts any influence on 5-alpha-reductase activity. The van der Merwe findings suggest a possible link, but the mechanism has never been established. Creatine does not have known direct interactions with steroidogenic enzymes. One hypothesis is that creatine might influence the rate of testosterone conversion indirectly through altered energy metabolism in tissues where 5-alpha-reductase is active, but this remains speculative.

No subsequent study has attempted to measure creatine's effect on 5-alpha-reductase activity directly. Without replication of the DHT findings, the van der Merwe result remains an isolated data point rather than an established effect.

Other Hormonal Markers

Some studies have examined whether creatine affects growth hormone, IGF-1, or cortisol. Schedel and colleagues (2000) found a transient increase in growth hormone following acute creatine ingestion, but this was short-lived and within physiological norms. Burke and colleagues (2008) found no significant changes in IGF-1 with creatine supplementation in older men. The cortisol literature is similarly unremarkable, with most controlled trials showing no meaningful shifts.

The consensus from the International Society of Sports Nutrition (ISSN) position stand on creatine (2017, updated 2021) does not list hormonal modulation as a recognized mechanism of creatine's ergogenic effects. The primary mechanisms remain phosphocreatine resynthesis, cell volumization, and enhanced training capacity.

The Hair Loss Question

Because DHT drives androgenetic alopecia, the van der Merwe study is frequently cited in discussions about creatine and hair loss. The logic chain runs: creatine raises DHT, DHT causes hair loss, therefore creatine causes hair loss. Each link in that chain has problems.

First, only one study has shown a DHT increase with creatine. Second, a single three-week observation in 20 rugby players does not establish a chronic effect. Third, hair follicle miniaturization is a slow process driven by years of DHT exposure in genetically susceptible individuals. A temporary elevation within normal range, even if real, does not automatically translate to clinically meaningful hair loss.

A 2021 review by Antonio and colleagues examined the available evidence and concluded that there is insufficient evidence to support the claim that creatine supplementation causes hair loss. The authors emphasized the need for properly designed studies measuring both DHT and hair-related outcomes simultaneously.

What the Evidence Actually Supports

Creatine monohydrate has been studied in over 500 peer-reviewed papers across multiple decades. Its effects on strength, power output, lean mass accretion, and exercise capacity are well-established. Its safety profile in healthy populations is supported by both short-term and long-term data.

On the hormonal front, the weight of evidence indicates that creatine does not significantly alter testosterone levels. A single study suggests a possible effect on DHT that has not been replicated. No study has demonstrated a downstream clinical consequence of any such hormonal change.

Researchers who study creatine extensively, including those at the ISSN, have consistently characterized the testosterone and hair loss claims as unsupported by the current evidence base. This does not mean the question is permanently closed. Replication studies measuring DHT, 5-alpha-reductase activity, and hair follicle outcomes would be valuable. Until such studies exist, the single van der Merwe data point does not warrant changing supplementation decisions.

Practical Takeaway

If you are considering creatine supplementation and have concerns about hormonal effects, the current evidence provides substantial reassurance regarding testosterone. The DHT question remains open but is built on a single unreplicated finding in a small sample. Individuals with a family history of androgenetic alopecia may reasonably choose to monitor, but the available data does not establish creatine as a cause of hair loss.

The responsible position is to acknowledge the gap, not fill it with certainty in either direction.