Health and Safety Related Issues


What are the possible side effects of creatine supplementation?

Research conducted on potential side effects of creatine supplementation focuses on three areas:

  1. 1.) Creatine supplementation and its effect on muscle dysfunction.
  2. 2.) Creatine supplementation and its effect on heat illnesses.
  3. 3.) Creatine supplementation and its effect on renal (kidney) and hepatic (liver) function.
  • Muscle Dysfunction
  • Since creatine supplementation has been shown to increase water retention in muscle cells it has been assumed to increase muscle injury and cramping.  However, research has not been able to scientifically support that creatine increases an athletes chance for muscle injury or cramping.

  • Greenwood et al. (2003) conducted an extensive 3 year study to examine the relationship between creatine supplementation and the occurrence of injuries for a NCAA Division IA football team (Rawson and Clarkson, 2003).  Results for both the creatine users and non-users were very similar.  The results were based on measurements of the following: In 2001, Rawson et al. reported no differences between creatine users and non-users for exercise induced muscle damage after performing high force eccentric exercises.  Data suggest that creatine supplementation does not increase the risk for muscle dysfunction.

    Creatine Supplementation and Musculotendinous Stiffness Watsford et al., 2003

    Dehydration and Heat Illness

    An anecdotal claim is that creatine supplementation increases the risk of dehydration and heat illness because it retains water in muscles that are need to regulate and maintain homeostasis in other regions of the body.  Volek et al. (2001) examined this claim testing 20 healthy men who either supplemented with creatine (.3g/kg body weight) or a placebo for 7 days.  The men performed a 30 minute cycling test at 60 - 70% of their VO2 max followed with three 10 second sprints in an environmental chamber at a temperature of 37*C and 80% humidity.  Data collected for heart rate, blood pressure, sweat rate, rectal temperature showed no differences between the creatine and placebo groups.  There were also no symptoms of cramping for either group.  The creatine group also had higher increases of peak power during the cycling test then the placebo group.  Research has developed several suggestions in regards to creatine loading prior to exercise.

    1. 1.)  It is advised that high dosing of creatine (20g/day) be avoided when athletes are trying to lose weight and are performing    strenuous activities under conditions of high heat and/or humidity (1997 Deaths of 3 NCAA wrestlers).
    2. 2.)  Pre-activity doses of creatine should be consumed at least 30 minutes before conducting activities during high heat
    3. and humidity.  This will ensure that absorption has occurred prior to the extreme conditions.
    4. 3.)  When fluid loss is high move post activity creatine doses back one hour.
    Creatine's Effects on Renal (Kidney) Function

    Anecdotal reports also state that creatine supplementation has a negative effect on kidney function.  However, research has found that this is not the case.

    Kreider et al. (2003) examined for a 21 month period the effects of creatine supplementation on renal function in 98 collegiate NCAA Division IA football players by collecting data on blood variables (muscle and liver enzymes, electrolytes, lipid profiles) and urinary measures.  The subjects were placed into 1 of 4 groups: 1.) non-users, 2.) users for 0 - 6 months, 3.) users for 7 - 12 months, and 4.) users for 12 - 21 months.  No differences in blood or urinary analysis were shown between the groups and all of the results were within normal ranges (Rawson et al., 2003).

    Research by Schilling et al. (2001) also confirmed that creatine supplementation did not effect kidney function.  His study consisted of 26 collegiate athletes who supplemented creatine.  The kidney function tests were within normal ranges for every athlete (Mottram, 2003).

    Due to the lack of research regarding the effects of creatine supplementation on pre-existing and recognized kidney dysfunction individuals with these conditions are advised to avoid creatine supplementation (Taes et al., 2003).

    Creatine's Effects on Hepatic (Liver) Function

    Studies also show that creatine supplementation does not effect liver function.  Waldron et al. studied the effects of creatine supplementation on liver function of 8 subjects during a 5 week high intensity exercise routine.  There were no reports of changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphate, albumin, creatinine, or total bilirubin.
    (Robinson et al., 2000)

    Miscellaneous Informational Links

    FDA reports
    FDA report on long term safety of creatine monohydrate

    What is Creatine Monohydrate? / Metabolism and Storage of Creatine / Energy Metabolism /Muscle Creatine Loading / Creatine, Exercise, and Sport Performance /Health and Safety Related Issues / Age, Gender, and Creatine Supplementation / Creatine and Clinical Use / Additional Links /