My doctor told me to stop taking creatine - The Kidney Myth

You’ve definitely had this conversation… or you’re most certainly going to.

A client comes in spooked. Bloodwork came back; creatinine was elevated. Their doctor told them to drop the creatine. Nothing else on the panel was off. Just that one number.

I had Dr. Mike T. Nelson on the podcast recently, and this came up. He’s a PhD exercise physiologist who’s been researching and using creatine since 1995, and his explanation of what's actually happening on that lab panel is the clearest I’ve heard. It’s worth having in your pocket before the next client texts you about it.

He also put together a 47-page manual on the whole topic. I asked him for a code for you. I'm sending it because this specific conversation comes up constantly, and most coaches handle it badly.

Mike’s Take on the Kidney Myth

I’ve been hearing this story for nearly two decades. It moves through coaching circles like a head cold. And every time, the bloodwork is fine, the kidneys are fine, and the supplement gets blamed for telling the truth.

Here’s the mechanism nobody mentions.

Creatine in your muscle isn't a permanent resident. It spontaneously degrades into

creatinine at roughly 1.7% of the total pool per day, and your kidneys clear that creatinine into urine. That’s the job. Kidneys remove waste; creatinine is the waste.

The creatinine number on a blood panel works as a kidney marker only because, under ordinary conditions, creatinine production is fairly stable. So if clearance drops, blood creatinine climbs, and the lab flags a possible problem.

Now add 5 grams a day of creatine to that system.

Nothing has been damaged. The input just went up. More substrate in means more creatinine out — more in the urine, and yes, slightly more circulating in the blood. The lab doesn’t know your client supplements. The clinician sees a number above the reference range and reaches for the conventional explanation.

That’s not kidney damage. That’s bookkeeping confusion.

What the safety literature actually shows: across hundreds of controlled trials and tens of thousands of participants, the side effect rate for creatine matches placebo. Both groups report adverse events at roughly 13–14%. The FDA classifies creatine monohydrate as Generally Recognized as Safe, which is the highest designation available to a food ingredient. The longest continuous high-dose use in the published record runs 14 years without adverse findings.

Dr. Darren Candow, who has spent his career investigating exactly this question:

“The entire body of evidence suggests it’s probably the safest, most effective ergogenic aid that we can now take. And the potential downside is — what? I can’t find one.”

Now the caveat, because the world is not made entirely of healthy adults.

There are populations where creatine should only be used with medical supervision. Not because of evidence of harm — because creatinine’s usefulness as a kidney biomarker breaks down in people who actually have kidney disease, and you don’t want an unreliable signal when the organ in question is already in trouble.

Those populations: chronic kidney disease stages 3 through 5, single kidney, polycystic kidney disease, and anyone on chronic nephrotoxic medication — high-dose NSAIDs, cyclosporine, aminoglycosides. For those clients, physician first, supplement second. That’s not hedging; it’s the actual clinical line.

For everyone else, the safety question is closed. The myth survives because it sounds plausible if you don’t know how the lab test works.

One practical tool, and this is the part I’d want you to keep: if a client’s creatinine comes back elevated and the question is genuinely whether kidney function is impaired, ask the clinician about running cystatin C instead. It’s an alternative filtration marker; it isn’t affected by creatine intake, and it sidesteps the confounder entirely.

That’s a far better conversation to have with a physician than “the internet says creatine is safe.”

Dr. Mike T. Nelson, PhD

The full myth-by-myth breakdown — kidneys, hair loss, cramping, dehydration, the steroid nonsense, plus the populations where caution genuinely applies — is Section 12 of the Complete Creatine Manual. 47 pages, 50+ peer-reviewed references, with Dr. Darren Candow, Dr. Scott Forbes, and Dr. Eric Rawson throughout.

$37. Code PAUL takes $10 off, so $27. 30-day refund, no questions asked.

https://creatine.miketnelson.com

PS. The hair loss thing traces back to one 2009 study in rugby players that measured a hormone ratio and never measured any actual hair loss. That’s the entire evidence base.

Twenty years of gym anxiety built on a single underpowered trial.

Keep Raising the Bar,

Paul Oneid MS, MS, CSCS