Is Creatine Safe With Fatty Liver? Enzymes and Creatinine

TL;DR

• Plain creatine monohydrate has a strong safety record in healthy adults, and studies have not found it raises liver enzymes. There are no human trials in people with fatty liver, so it is not proven for or against.
• Two lab quirks cause false alarms: creatine can raise creatinine (a kidney marker) without hurting your kidneys, and hard lifting can raise ALT and AST (liver markers) for a week.
• Skip multi-ingredient “pre-workout” and bodybuilding blends, which are the supplements linked to liver injury. Check with your doctor first, especially with cirrhosis or kidney disease.

Creatine monohydrate is generally considered safe for the liver in healthy adults, and having fatty liver (MASLD, metabolic dysfunction-associated steatotic liver disease, formerly NAFLD) is not a known reason to avoid it. But there are no human studies in people with fatty liver, so “probably fine” is the most honest answer, and your doctor should have the final word.

The more common problem is confusing lab results. Creatine and heavy training can each push a blood test in a way that looks alarming and is not.

What does the research say about creatine and the liver?

For healthy people, the safety record is long:

• A review of safety studies found that “liver (enzymes, urea) and kidneys (glomerular filtration urea and albumin excretion rates) show no change in functionality in healthy subjects supplemented with creatine, even during several months, in both young and older populations.”
• The International Society of Sports Nutrition (ISSN) position stand concluded that short- and long-term supplementation, up to 30 g a day for 5 years, was safe and well tolerated in healthy people and some patient groups. It noted that the only consistently reported side effect has been weight gain.

For fatty liver specifically, the evidence is thin:

• Animal research, mostly in rodents on high-fat diets, points to a possible benefit for fat buildup in the liver. It is preclinical, and doses used in animals are much higher than those people take.
• A 2023 review of creatine in chronic liver disease said it was “barely investigated and not studied in human patients.”

So creatine is neither a proven treatment nor a known danger for fatty liver. It is a supplement for muscle and strength. And for people with MASLD, strength training itself is worth doing, because exercise supports weight loss and metabolic health. See how to reverse fatty liver.

Why does creatine raise creatinine?

Your body makes creatinine when it breaks down creatine, and doctors use the blood level of creatinine to estimate kidney function. If you take creatine, your creatinine may read a bit higher even when your kidneys are working normally.

The evidence:

• A 2025 systematic review and meta-analysis in BMC Nephrology reviewed 21 studies (12 were pooled for serum creatinine) and found creatine supplementation was associated with a small but statistically significant rise in serum creatinine, but no significant change in glomerular filtration rate (GFR). The authors concluded the rise was “likely due to metabolic turnover rather than renal impairment.”
• A randomized, placebo-controlled trial in 18 healthy men took about 10 g of creatine a day for three months and found no sign of kidney problems. Cystatin C, a kidney marker not tied to muscle creatine, actually decreased over time.

What to do about it:

• Tell the clinician you take creatine before any kidney test, since many labs estimate kidney function from creatinine.
• Ask about cystatin C if a creatinine-based result looks off. Your doctor decides whether that test is needed.
• Do not self-diagnose kidney trouble from a single creatinine value, or ignore a real warning because you assume it is the creatine.

If you have existing kidney disease, ask before starting. The ISSN advises people with pre-existing renal disease to consult a physician before using creatine, and a review recommended that high doses (above 3–5 g a day) not be used by people with kidney disease or risk factors such as diabetes, high blood pressure or reduced GFR.

Can lifting and creatine raise ALT and AST?

Lifting can. Creatine is not the established cause.

ALT and AST are called liver enzymes, but they are also found in muscle. In one study from Sweden, 15 healthy men who were not used to weightlifting did a one-hour lifting session. AST, ALT, lactate dehydrogenase, creatine kinase and myoglobin all rose significantly and stayed up for at least 7 days. GGT, ALP and bilirubin stayed normal. The authors said intense muscular exercise should be considered a cause of asymptomatic liver test elevations.

That matters for you because ALT and AST are your fatty liver monitoring numbers. If you start a lifting program, add creatine and then see higher enzymes, it may be muscle, not liver. Some clues:

• GGT, ALP and bilirubin stayed normal in that study, so a rise in ALT and AST alone, with those normal, fits muscle. Our AST/ALT ratio guide explains how the pair is read.
• Creatine kinase (CK) is high if muscle is the source. Your doctor can order it.

Practical advice: in that study enzymes stayed raised for at least a week in men new to lifting, so ask your doctor how long to rest hard training before a blood test, and tell your clinician about your training. For more on what the numbers mean, see ALT and AST levels in fatty liver.

What about the rest of the label?

The supplements that have hurt livers are usually not plain creatine. A review in Hepatology sponsored by the AASLD and NIH found herbal and dietary supplements account for about 20% of drug-induced liver injury cases in US research data, with anabolic steroids, green tea extract and multi-ingredient nutritional supplements the main agents. A Drug-Induced Liver Injury Network study of 44 young men found bodybuilding supplements caused prolonged jaundice, and in some cases product analysis found anabolic steroids that were not on the label.

So the form matters:

Product type	Liver risk concern
Plain creatine monohydrate powder	Low, based on the evidence above
Creatine blended with other ingredients	Unknown; the extras are the issue
”Pre-workout” or “fat burner” blends	Higher; may contain stimulants, herbal extracts
”Bodybuilding” or “muscle builder” prohormone products	Highest; anabolic steroid contamination is documented

Choose a single-ingredient creatine monohydrate that has been independently tested if you can, and stop and call your doctor if you develop jaundice, dark urine, severe itching or unexplained fatigue.

How should you take creatine with fatty liver?

If your doctor agrees:

• Dose: the ISSN says maintenance with 3–5 g a day keeps muscle stores topped up. A “loading” phase of 20 g a day for 5–7 days is optional and not necessary.
• Hydration: drink water through the day; this is general good practice, not something studies in fatty liver require.
• Weight: expect your scale weight to rise a little early on. That is the one consistently reported effect and is often attributed to extra water in muscle. Do not mistake it for fat gain, and do not chase it as a weight loss problem.
• Alcohol: if you have significant fibrosis or cirrhosis, the advice is no alcohol at all, supplements or not. See is alcohol safe with fatty liver.
• Cirrhosis: muscle loss (sarcopenia) is a real problem in advanced disease, and researchers have raised creatine as a possible tool, but it has not been studied in patients. Do not start without your hepatologist’s go-ahead.

If you track protein too, our guide to protein shakes covers the other common gym supplement.

The Bottom Line

Creatine monohydrate does not have a record of harming the liver in healthy adults, and fatty liver is not a recognized reason to avoid it. There are no human trials in fatty liver, and it is not a treatment for it.

The biggest practical issues are false alarms: a creatinine bump that is not kidney damage, and ALT and AST that rise after lifting. Tell your doctor what you take and when you train, avoid multi-ingredient blends, and get a personal OK first if you have cirrhosis or kidney disease.

Sources

• Kim HJ, et al. Studies on the safety of creatine supplementation. Amino Acids. 2011.
• Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017.
• Naeini EK, et al. Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrol. 2025.
• Gualano B, et al. Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. Eur J Appl Physiol. 2008.
• Pettersson J, et al. Muscular exercise can cause highly pathological liver function tests in healthy men. Br J Clin Pharmacol. 2008.
• Casciola R, et al. Creatine supplementation to improve sarcopenia in chronic liver disease: facts and perspectives. Nutrients. 2023.
• Navarro VJ, et al. Liver injury from herbal and dietary supplements. Hepatology. 2017.

This article is for informational purposes only and is not medical advice. Talk to your doctor or hepatologist about your specific situation.