Creatine is the most researched supplement in sports nutrition. Over 500 peer-reviewed studies span nearly four decades. Yet somehow the internet is still full of contradictory claims: it causes hair loss, it damages kidneys, you need to load it, you don't need to load it, it's a steroid, it's water weight.
After running hundreds of studies through a quality-scoring framework, here's what the actual evidence shows.
The core finding is boring, which is why it's true
Creatine monohydrate, at ~5g per day, increases muscular strength and power output by 5–15% over 4–12 weeks, in trained and untrained populations, in men and women, in older and younger adults. This is the single most replicated finding in supplement science.
Effect sizes cluster tightly. Almost every high-quality RCT reports the same range. That kind of consistency is what you look for when separating real effects from noise.
Loading is optional
The "loading phase" (20g/day for 5–7 days) saturates muscle stores in about a week. Taking 5g/day gets you to the same saturation in 3–4 weeks. The endpoint is identical.
Loading is faster. That's it. Not required, not more effective, not superior.
The "hair loss" study everyone quotes
One 2009 study on rugby players showed a modest increase in DHT (a hormone linked to male pattern baldness). It had 20 participants, no measurement of actual hair loss, and has never been replicated.
That single underpowered study is the entire foundation for the "creatine causes baldness" claim you'll see on Reddit and TikTok. Dozens of subsequent studies looking at hormonal markers found no significant DHT changes.
If you're genetically predisposed to male pattern baldness, you'll lose your hair whether you take creatine or not. If you're not, creatine won't cause it.
Kidney damage: the myth that won't die
Serum creatinine (a kidney function marker) goes up when you take creatine. That's because you have more creatinine in your bloodstream — not because your kidneys are damaged.
Studies measuring actual kidney function (GFR, cystatin C) in healthy people taking creatine for up to five years show no adverse effects. This has been reviewed by the International Society of Sports Nutrition, the American College of Sports Medicine, and independent research groups. All conclude the same thing: safe.
If you have pre-existing kidney disease, don't take creatine without a doctor. If you don't, you're fine.
What form should you take
Creatine monohydrate. That's it.
Creatine HCl, creatine ethyl ester, creatine nitrate, buffered creatine — these all cost more and have zero evidence of being superior. The monohydrate research base dwarfs everything else combined.
The "micronized" version might dissolve slightly better in water. That's the only real difference worth paying more for, and it's about $2 extra.
What creatine does NOT do
- Build muscle by itself. It amplifies training. No training = no results.
- Work for everyone. About 20–30% of people are "non-responders" (usually because they already have high natural stores from meat consumption).
- Cause dehydration or cramping. This was theorized in the 90s; controlled studies have consistently failed to find it.
- Boost testosterone. Some studies show minor DHT changes; testosterone itself is unchanged.
The evaluation framework
When you read a supplement study, four things matter more than the conclusion:
- Sample size — Under 30 participants, treat findings as preliminary. Over 100, more confidence.
- Duration — Under 4 weeks, you're often measuring acute effects, not real adaptation.
- Funding source — Company-funded studies are ~4× more likely to report favorable results (Lesser et al., PLoS Medicine).
- Effect size — A 1–2% improvement in a study of 20 people is noise. A 10% improvement across 200 people replicated three times is real.
This is the framework we built Q-SCI around. You paste a study, and it scores methodology, funding bias, and effect strength on a 0–100 scale. Try it on any creatine study — the good ones score 80+, the marketing-funded ones tend to score under 50.
Bottom line
- 5g/day creatine monohydrate
- Take it any time (timing doesn't matter for saturation)
- Skip the loading phase unless you're impatient
- Don't waste money on "advanced" forms
- Expect 5–15% strength gains over 1–3 months
- Ignore the hair loss and kidney panic
Creatine is the boring, cheap, well-studied supplement that actually does what the label claims. The exception, not the rule, in this industry.
This article draws on the Q-SCI research quality database. If you want to score your own supplement studies, the free evaluator is at q-sci.org.
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