Creatine Long-Term Safety: What a Major Follow-Up Study Found

Creatine Long-Term Safety: What a Major Follow-Up Study Found

One persistent myth surrounds creatine: that it is harmful to the kidneys. This fear has been the primary reason many people avoid creatine. But what does science actually say? The answer may surprise you — the evidence overwhelmingly supports creatine's safety.

Poortmans & Francaux 2000: Five-Year Follow-Up

One of the most important long-term safety studies is the work of Poortmans & Francaux (2000), which tracked creatine users over a period of up to 5 years. This was not a short-term laboratory test — it examined real people's real long-term creatine use.

The results were clear:

• No renal dysfunction detected — glomerular filtration rate (GFR), creatinine clearance, and other kidney markers remained within normal ranges
• Kidney markers of creatine users did not differ from the control group
• Even with long-term use, no cumulative negative effects appeared

Kreider et al. 2003: Up to 21 Months of Monitoring

Another significant study by Kreider et al. (2003) followed athletes who consumed creatine for up to 21 months. Multiple health markers were evaluated:

• 69 health markers were assessed regularly
• Kidney function, liver function, blood lipids, blood sugar — all remained within normal ranges
• No clinically significant adverse effects were detected
• Researchers concluded that creatine monohydrate is safe for long-term consumption

ISSN Position on Safety

The International Society of Sports Nutrition (ISSN) is unequivocal on creatine safety:

"Creatine monohydrate is one of the safest and most well-studied supplements available."

The ISSN position stand (Kreider et al., 2017) emphasises:

• Long-term studies (up to 5 years) have not identified clinically significant side effects
• Creatine is even used in clinical settings in certain patient populations
• The only documented side effects are slight weight gain (water retention) and occasional gastrointestinal discomfort during loading

Origin of the Kidney Myth

Where does this fear come from? The explanation is simple but confusing:

1. Creatinine is a metabolic by-product of creatine that kidneys filter
2. Elevated blood creatinine is a marker of kidney damage — when kidneys filter poorly
3. Creatine supplementation naturally raises creatinine levels because there is more creatine in the body
4. This means creatine users appear to have higher creatinine, but this does not reflect kidney damage

Doctors need to be aware that a patient takes creatine to correctly interpret creatinine levels. This is a diagnostic nuance, not a safety problem.

Water Retention: Fact vs Fiction

One documented effect of creatine is temporary water retention. Important context:

• Initial weight gain is typically 1–3 kg during the first 1–2 weeks
• This water is intracellular — meaning it is stored inside muscle cells
• This is not subcutaneous bloating or a "puffy" appearance
• The effect stabilises and does not increase over time
• After stopping creatine, water levels normalise within a few weeks

Intracellular water retention may actually be beneficial — it contributes to muscle cell volume and potentially protein synthesis.

Who Should and Shouldn't Take Creatine

Creatine is suitable for:

• Healthy adults (both men and women)
• Athletes and active individuals
• Older adults (combined with resistance training)
• Vegetarians and vegans

Consult your doctor if:

• You have an existing kidney condition
• You take medications (especially those affecting kidneys)
• You are pregnant or breastfeeding
• For individuals under 18, insufficient safety data exists

Optimal Safety Practices

1. Use creatine monohydrate — the most studied form with the most safety data
2. Stick to recommended doses: 3–5g daily
3. Drink adequate water — while no proven link exists between creatine and dehydration, adequate fluid intake is always sensible
4. Inform your doctor about creatine use — especially before blood tests
5. Do not exceed recommended doses — more is not better

EFSA-approved claim: "Creatine increases physical performance in successive bursts of short-term, high-intensity exercise" — at a dose of 3g daily.

Summary

• Poortmans & Francaux (2000): 5-year follow-up — no kidney damage detected
• Kreider et al. (2003): up to 21 months — 69 markers normal
• ISSN: "One of the safest and most well-studied supplements available"
• Elevated creatinine is normal, not a sign of kidney damage
• Water retention (1–3kg) is intracellular and temporary
• No proven risks in healthy individuals at recommended doses

References

• Poortmans, J. R., & Francaux, M. (2000). Long-term oral creatine supplementation does not impair renal function in healthy athletes. Medicine & Science in Sports & Exercise, 32(8), 1459–1461.
• Kreider, R. B., Melton, C., Rasmussen, C. J., Greenwood, M., Lancaster, S., Cantler, E. C., Milnor, P., & Almada, A. L. (2003). Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Molecular and Cellular Biochemistry, 244(1–2), 95–104.
• Kreider, R. B., Kalman, D. S., Antonio, J., Ziegenfuss, T. N., Wildman, R., Collins, R., Candow, D. G., Kleiner, S. M., Almada, A. L., & Lopez, H. L. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. Journal of the International Society of Sports Nutrition, 14, 18.
• Persky, A. M., & Rawson, E. S. (2007). Safety of creatine supplementation. Sub-Cellular Biochemistry, 46, 275–289.

Dietary supplements are not a substitute for a varied, balanced diet and healthy lifestyle.

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