What the Research Says
Multiple large-scale reviews and meta-analyses conclude that creatine supplementation is safe for both short- and long-term use. A 2021 expert consensus paper noted that over 500 peer-reviewed publications support the tolerability of creatine at recommended dosages (3–5 g/day or 0.1 g/kg/day) [1]. Similarly, a 2021 update in Current Sports Medicine Reports states that both short- and long-term supplementation is safe and well tolerated in healthy individuals and several patient populations [2].
The most comprehensive safety analysis to date examined 685 human clinical trials and found no significant difference in the frequency of 35 different side effects between participants taking creatine and those taking placebo. Among 12,839 creatine users and 13,452 placebo users, 4.60% of creatine users reported a side effect versus 4.21% of placebo users (p=0.828) [6]. Even when analyzing gastrointestinal issues, muscle cramping, or renal markers, no significant differences emerged [6].
Long-term high-dose use was also evaluated: one large clinical trial involved creatine supplementation for up to 8 years, and the side effect rates were similar between groups (80.9% for creatine vs. 77.2% for placebo) [6]. A 2025 literature review confirmed that creatine supplementation does not adversely affect kidney or liver function, even with prolonged high-dose intake [4].
Caveats and Specific Populations
While creatine is generally safe, most evidence comes from healthy adults. Studies in children and adolescents are limited, but available data suggest no harm when used appropriately [1][3]. For older adults and clinical populations (e.g., those with neurological or musculoskeletal conditions), creatine appears safe and may offer additional benefits [1][4].
A 2025 systematic review on combat sport athletes reported no serious adverse effects from creatine supplementation, even when athletes aimed to reduce body mass for weight classes [5]. However, creatine can increase body mass, especially with longer-term use (≥6 weeks) or when combined with resistance training [5]. This is a desired effect for many athletes but may be a consideration for those needing to make weight.
The 2021 expert review addressed common misconceptions, noting that creatine does not cause kidney damage, dehydration, muscle cramping, or hair loss in healthy individuals [1]. The safety profile is robust, but individuals with pre-existing renal conditions should consult a healthcare provider before supplementation [1][6].
Sources used in this answer
Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show?
Creatine supplementation at 3–5 g/day is well tolerated, and common concerns (kidney damage, dehydration, hair loss) are not supported by evidence from over 500 peer-reviewed studies [1].
Creatine Supplementation: An Update
Short- and long-term creatine supplementation is safe and well tolerated in healthy individuals and patient populations [2].
Creatine Supplements: What the Research Says about How It Can Help Healthy Athletes
Short- and long-term creatine supplementation is safe and well tolerated in healthy individuals and several patient populations [4].
The Impact of Creatine Supplementation on Physical Performance, Cognitive Functions, and Safety – A Literature Review
Creatine supplementation showed no adverse effects on kidney or liver function, even with long-term high-dose use, and improved lean body mass by a mean of 1.32 kg [5].
Creatine Supplementation in Combat Sport Athletes: A Narrative Systematic Review
No serious adverse effects were reported across 19 studies in combat sport athletes; creatine increased body mass and fat-free mass but did not impair recovery or endurance [6].
Safety of creatine supplementation: analysis of the frequency of reported side effects in clinical trials
In an analysis of 685 clinical trials, 4.60% of creatine users reported side effects vs. 4.21% of placebo users (p=0.828), with no significant differences in gastrointestinal, muscle, or renal issues [7].