Is Creatine Safe? Evidence on Kidneys, Hair, and Side Effects

Creatine has been commercially available since the early 1990s and has been the subject of more than 500 published studies. No other sports supplement has this depth of safety data. Yet misconceptions persist, driven largely by a misunderstanding of kidney markers and one poorly replicated study about hair.

Kidney Function: The Creatinine Confusion

This is the most common concern, and it stems from a measurement artifact. When your body metabolizes creatine, one of the byproducts is creatinine — a molecule routinely measured in blood tests as a marker of kidney function. Higher creatinine levels can indicate kidney dysfunction. But creatine supplementation raises creatinine levels simply by providing more substrate for its production, not by damaging kidneys [1].

Poortmans and Francaux published a comprehensive safety review in which they found no evidence of renal dysfunction in healthy individuals supplementing with creatine at recommended doses, even over periods exceeding 5 years [2]. Their conclusion was unambiguous: creatine does not damage healthy kidneys.

The important caveat: individuals with pre-existing kidney disease are a different population. The research in this group is limited, and it would be prudent to consult a nephrologist before supplementing [3].

Hair Loss and DHT: One Study, Never Replicated

In 2009, van der Merwe et al. published a study showing that creatine supplementation increased dihydrotestosterone (DHT) levels by 56% in college-aged rugby players after a 7-day loading protocol [4]. Since DHT is implicated in androgenetic alopecia (male pattern baldness), this generated concern.

However — and this is critical — no subsequent study has replicated this finding. A comprehensive 2021 review by Antonio et al. examined 12 studies measuring testosterone and DHT responses to creatine and found no consistent effect on either hormone [5]. The van der Merwe study has notable limitations: small sample size, no control for diet, and unusually high loading dose.

The current scientific consensus: there is insufficient evidence to conclude that creatine causes hair loss.

Gastrointestinal Effects

Some users report stomach discomfort, particularly during loading phases at 20 g/day. This is typically resolved by splitting the dose into 4–5 servings throughout the day or by using the maintenance-only approach at 3–5 g/day [6]. Taking creatine with food also reduces GI complaints.

The Long-Term Data

Kreider et al.'s 2017 ISSN position stand — the most comprehensive review of creatine research to date — concluded that creatine monohydrate is the most effective and safest nutritional supplement available for increasing high-intensity exercise capacity and lean body mass [7]. This isn't a marginal endorsement. It's a strong, evidence-based position statement from the field's leading professional organization.