Creatine is one of the most studied supplements there is, and in healthy people at normal doses it has not been shown to damage the kidneys. The problem is that it can make your kidney test look worse than it is, and that confuses a lot of doctors and scares a lot of lifters.
I see this in the gym crowd and in the fighters who come through our combat sports clearance program. A routine blood test comes back with a high creatinine, someone says the word "kidney," and the creatine gets blamed. Sometimes correctly. Usually not.
Why creatine makes your kidney test look bad
Creatinine, the number on your blood test, is a breakdown product of creatine. Take more creatine and your body makes more creatinine. The lab sees a higher creatinine and calculates a lower eGFR, the standard estimate of kidney function.
But the kidneys have not changed. They are just clearing more of a waste product you are feeding them. Large amounts of muscle do the same thing, which is why bodybuilders often get flagged even without supplements.
How to get an accurate kidney test if you take creatine
- Ask for a cystatin C test. It measures kidney function using a different protein that creatine does not affect. The current race-free equations combining creatinine and cystatin C are more accurate for muscular people.
- Or pause creatine for about a week before a blood test that matters, such as a fight physical or an insurance exam.
- Tell whoever orders the test that you take creatine. It saves a lot of worry and a lot of unnecessary referrals.
- Check a urine albumin test. Creatine does not raise it. If the urine is normal and cystatin C is normal, the kidney is almost certainly fine.
What the research shows in healthy people
The International Society of Sports Nutrition reviewed the evidence and concluded that creatine at recommended doses is safe for healthy adults, including long-term use. A 2019 meta-analysis looking specifically at kidney function found no meaningful harm at typical doses.
Typical doses are 3 to 5 grams a day. Some people "load" with about 20 grams a day for five to seven days first. Loading is not necessary and raises the creatinine number more.
When creatine is not a good idea
- Existing kidney disease. There is not enough data in people with reduced kidney function, and the creatinine confusion makes it harder to track their real disease. I tell my kidney patients to skip it unless we have talked about it.
- Combined with dehydration. Weight cuts, sauna sessions, and hard training in the heat strain the kidneys on their own. Adding high-dose creatine and NSAIDs on top of a cut is a combination I would avoid. Our post on weight cutting and your kidneys explains why.
- Combined with NSAIDs , especially daily ibuprofen for training aches.
- Diabetes or high blood pressure that is not well controlled , because both already raise kidney risk.
- Products that are not third-party tested. Supplements are not checked by the FDA before sale. Some "creatine" products have been found contaminated with other substances. Look for NSF Certified for Sport or a similar seal, which also matters for tested athletes.
Creatine vs. protein: which one do you need?
They do different things.
Creatine helps your muscles produce quick bursts of energy, which lets you do a few more reps or more explosive work. Over time that can add strength and some muscle size. It does not replace food.
Protein is the raw material for building and repairing muscle. Most active adults do well with about 1.2 to 2.0 grams per kilogram of body weight a day, mostly from food, with powder to fill gaps.
In healthy people, both are fine together. In people with chronic kidney disease, high protein intake can speed up kidney damage, so protein targets should come from your nephrologist or a renal dietitian rather than a gym chart.
What to do with a high creatinine on a blood test
Do not panic, and do not assume it is the creatine. Repeat the test with a cystatin C, check a urine albumin, drink normally the day before, and avoid a hard workout in the 24 hours before the draw. If those come back normal, you are almost certainly fine. If they do not, something else is going on and it is worth seeing a nephrologist. Our chronic kidney disease page explains what we look at.
Does creatine cause kidney stones?
There is no good evidence that creatine at normal doses causes kidney stones. Dehydration does, and people taking creatine are often training hard in the heat. Drink enough to keep your urine pale yellow, especially on long training days.
How much water should you drink with creatine?
No special amount is needed. Drink to thirst, more on hot or heavy training days, and treat dark urine as a sign you are behind.
Getting care in Houston
Remix Medical is a physician-owned practice with nephrology offices in Montrose near the Texas Medical Center, East Houston, Katy, and Groesbeck, plus video visits anywhere in Texas. Through our combat sports clearance program, we also run pre-fight physicals and kidney labs for boxing, MMA, and grappling athletes. Most plans are accepted, including Medicare, Medicare Advantage, and Texas Medicaid. Book an appointment or ask for a video visit.