What are the potential adverse effects of taking creatine (Creatine Monohydrate) supplements?

Adverse Effects of Creatine Supplementation

Creatine supplementation is generally considered safe, but may cause transient water retention, gastrointestinal complaints, and muscle cramps, with individuals with pre-existing kidney disease, diabetes, hypertension, or reduced glomerular filtration rate advised to avoid high-dose supplementation (>3-5 g/day). 1

Common Side Effects

• Water retention: Most common side effect, typically occurring in the early stages of supplementation 2
• Gastrointestinal complaints: Including:
  • Nausea
  • Vomiting
  • Abdominal cramps
  • Diarrhea 3
• Muscle cramps: Reported anecdotally by some athletes 4
• Weight gain: Due to increased water retention in muscles 1
• "Fishy" body odor: May occur at doses of approximately 3 g/day 5

Renal Considerations

Kidney function is a primary concern with creatine supplementation:

• Healthy individuals: Multiple studies show no significant changes in kidney function parameters in healthy subjects supplemented with creatine, even during several months of use 4
• At-risk populations: High-dose creatine supplementation (>3-5 g/day) should be avoided by:
  • Individuals with pre-existing kidney disease
  • Those with diabetes
  • People with hypertension
  • Individuals with reduced glomerular filtration rate 1, 4
• Laboratory confusion: Creatine supplementation may transiently increase serum creatinine levels, which can mimic kidney disease on lab tests 6
• Rare case reports: Although extremely rare, there have been isolated case reports of acute tubular necrosis associated with creatine supplementation 7

Dosing Considerations and Safety

• Standard protocol: Loading phase of ~20g/day divided into four 5g doses for 5-7 days, followed by maintenance of 3-5g/day 1
• Alternative approach: Lower dose approach (3-5g/day without loading) can achieve similar increases in muscle phosphocreatine over time and may minimize side effects 1
• Hydration: Maintaining adequate hydration is recommended when using creatine supplementation 1
• Duration: Limited data exist on very long-term use (multiple years), though studies of several months show good safety profiles in healthy individuals 4

Special Precautions

• Discontinuation recommendation: Creatine supplementation should be discontinued if evidence of renal dysfunction appears 1
• Medication interactions: Caution is advised when combining creatine with potentially nephrotoxic medications 6
• Pre-supplementation screening: Consider kidney function assessment before starting supplementation in individuals with risk factors 4
• Product quality: Choose supplements tested by reputable third-party testing programs to reduce risk of contamination 1

Monitoring Recommendations

For those using creatine supplements, especially at higher doses or for extended periods:

• Monitor for gastrointestinal symptoms
• Be aware of potential water retention effects
• Consider periodic kidney function assessment if using long-term
• Discontinue use if unusual symptoms develop 1

While creatine is one of the most well-studied supplements with a generally good safety profile, understanding these potential adverse effects allows for appropriate monitoring and risk mitigation.