What the research does—and does not—show
A 2026 systematic review found that creatine supplementation increased blood creatinine and lowered kidney-function estimates calculated from creatinine. A separate method of measuring kidney filtration did not show a significant change. The authors considered altered creatinine metabolism a likely explanation, rather than evidence of kidney injury. [2]
That is not a study of taking creatine with isotretinoin. It cannot confirm that the combination is safe, or tell you which supplement dose to use during treatment. The review also identifies gaps in evidence for people with kidney disease who are not receiving dialysis. [2]
Creatinine and CK are not the same test
- Creatinine is a blood marker used to help estimate kidney function. Creatine supplementation can raise it without necessarily meaning kidney damage—but an abnormal result still needs clinical interpretation. [2]
- CK, also called CPK, is a different blood test associated with muscle injury. Isotretinoin labeling describes increased CPK in some people doing vigorous exercise and rare reports of rhabdomyolysis, a serious muscle-breakdown condition. [1]
Do not dismiss a flagged result as “just the creatine,” or assume a normal kidney result clears you for hard training. Tell the clinician interpreting your tests about both the supplement and your recent exercise. [1] [2]
What to check before starting—or if you already take it
Show your prescriber or pharmacist the full product label, not just the word “creatine.” Include how much you take, when you started, other supplements, and the type and intensity of your workouts. Mention any kidney problems, abnormal test results, muscle pain, or weakness. [1] [2]
Ask whether to continue the supplement and whether your monitoring or exercise plan needs to change. Do not lower or skip isotretinoin doses to make room for a supplement. Its Medication Guide says to take it exactly as prescribed and discuss new medicines with your healthcare provider. [1]
Avoid supplements containing vitamin A while taking isotretinoin. A product being vitamin A-free does not establish that its other ingredients are suitable for you. Our supplement guide explains what to check. [1]
Muscle symptoms: when to stop and get advice
The U.S. isotretinoin Medication Guide instructs patients to stop taking isotretinoin and contact their healthcare provider right away for muscle or joint pain or weakness. Muscle weakness, with or without pain, can signal serious muscle damage. Do not push through a workout or wait for a routine blood test when these symptoms occur. [1]
These warnings concern isotretinoin; they do not prove that creatine causes the muscle problems. Discuss hard physical activity with your prescriber, and see our exercise guide for the broader training precautions. [1]