What are the potential side effects of creatine (creatine monohydrate) supplementation?

Side Effects of Creatine Monohydrate Supplementation

Creatine monohydrate is generally safe for most individuals, with the most common side effect being transient water retention in the early stages of supplementation, while those with pre-existing kidney disease, diabetes, hypertension, or reduced glomerular filtration rate should avoid high-dose supplementation. 1, 2

Common Side Effects

• Water retention: The most frequently reported side effect, particularly during the loading phase
• Weight gain: Typically 1-2 kg during initial supplementation due to increased water content in muscles
• Gastrointestinal discomfort: Occasionally reported, including:
  • Stomach cramps
  • Nausea
  • Diarrhea
• Muscle cramps: Anecdotally reported by some athletes, though not consistently demonstrated in research 3

Safety Profile

Creatine monohydrate has been extensively studied and is considered relatively safe when used at recommended doses:

• Standard dosing protocols:

  • Loading phase: 0.3 g/kg/day (typically 20g/day divided into 4 equal doses) for 5-7 days
  • Maintenance phase: 3-5 g/day 4
  • Alternative approach: 3-5 g/day without loading (takes longer to achieve effects) 1

• Kidney function: Despite concerns, well-controlled studies have not shown adverse effects on kidney function in healthy individuals 2, 3

• Liver function: No evidence of dysfunction based on serum enzyme markers during medium-term (4 weeks) supplementation 3

High-Risk Populations and Contraindications

Creatine supplementation should be avoided or used with caution in:

• Individuals with pre-existing kidney disease
• People with diabetes
• Those with hypertension
• Individuals with reduced glomerular filtration rate
• Pregnant and breastfeeding women 1, 2

Practical Considerations

• Hydration: Maintaining adequate hydration is recommended when using creatine supplementation 1
• Quality control: Choose products tested by reputable third-party testing programs (e.g., 'Informed Sport' or 'HASTA') 1
• Body odor: Some users may experience a "fishy" body odor at doses around 3 g/day 1
• Discontinuation: Consider stopping use if experiencing unusual symptoms or evidence of renal dysfunction 1

Long-term Safety

Long-term studies (up to 5 years) have not demonstrated adverse effects on renal function in healthy individuals 3. However, regular monitoring is advisable for extended use, particularly at higher doses.

Monitoring Recommendations

For individuals using creatine supplementation, especially at higher doses or for extended periods:

• Monitor for unusual symptoms
• Consider baseline and periodic assessment of renal function if using long-term
• Discontinue use if adverse effects occur 1

While media reports have sometimes emphasized potential health risks, scientific evidence indicates that creatine monohydrate supplementation is generally well-tolerated when used appropriately by healthy individuals 3.