Palm Beach Gardens Fire Rescue Health & Wellness

Creatine, Hydration, and the Biggest Myth in the Weight Room

If you’ve spent any time around old school doctors or even first responders, you’ve probably heard this one: “Don’t take creatine, it’ll dehydrate you.” Sounds convincing, especially when you’re already sweating through gear on a call. The problem is, this belief is not supported by the bulk of controlled research. Let’s break it down in a way that actually makes sense for the job.

What creatine actually does in your body

Creatine is stored in your muscles and helps you produce quick energy for high-intensity work like stairs, forcible entry, dragging hose, or lifting heavy equipment. It works by helping regenerate ATP, your body’s immediate energy source during short bursts of effort¹. That is why it is one of the most researched and effective supplements for performance.

Creatine is also osmotically active, meaning it pulls water into your muscle cells¹. That is where the confusion starts. People hear “water shift” and assume dehydration, but that is not what is happening. This is hydration inside the muscle, not fluid loss from the body.

Early studies showed short-term increases in total body water during loading phases, which led people to assume creatine was negatively impacting hydration¹. However, those early findings were taken out of context. When you look at longer-term and controlled data, the story changes.

Does creatine actually cause dehydration?

Short answer: no. Long answer: Controlled studies consistently show that creatine does not increase dehydration risk, even in hot and physically demanding environments². This is especially relevant for first responders dealing with heat stress, heavy gear, and long shifts.

In fact, research has shown:

  • No impairment in hydration or thermoregulation²
  • No increase in cramping or heat illness risk²
  • In some cases, improved fluid balance and heat tolerance²

Long-term safety data also show no evidence that creatine negatively impacts thermoregulation or increases risk of heat-related issues when taken at recommended doses⁴. Across more than 25 years of research, creatine has not been shown to impair hydration, renal function, or muscle function in healthy individuals⁴.

A large body of evidence demonstrates that creatine does not negatively impact hydration markers, sweat rate, or electrolyte balance during exercise in the heat².

Where things get a little more nuanced

Not every study shows the exact same outcome, and this is where context matters. A large population-based study looking at dietary creatine intake found that moderate intake had neutral effects on hydration, while very high or very low intakes were associated with changes in hydration biomarkers³. These changes included shifts in total body water and plasma osmolality, although the study could not determine cause and effect³.

Key takeaway from that data:

  • Moderate intake appears neutral for hydration³
  • Extremely high intake may alter fluid balance markers³
  • Real-world hydration is influenced by many factors like fluid intake, caffeine, alcohol, and activity³

This does not contradict performance research. It just reinforces that more is not always better and that hydration is multifactorial.

Why the myth stuck around

There are a few reasons this one refuses to die. First is water weight confusion. People often gain a few pounds when starting creatine and assume something negative is happening. In reality, that increase is largely due to water being pulled into muscle tissue, not dehydration¹.

Second is old school advice. Early guidelines were cautious, especially for athletes training in heat, before we had stronger research to guide recommendations². That messaging stuck, even as better data came out.

Third is poor supplement practices. Some people were taking excessive doses or stacking creatine with other supplements, which can lead to side effects that get blamed on creatine itself. When dosing is appropriate using creatine alone, these issues are far less common².

What happens to hydration over time

When you zoom out beyond the first few days, things level out. Long-term research shows no consistent disruption in fluid balance or hydration status with recommended dosing². Your body regulates intracellular and extracellular fluid just fine.

Research shows:

  • No impairment in hydration markers during exercise²
  • Stable electrolyte levels and plasma volume²
  • No increased risk of dehydration or heat illness²

In simple terms, your body adapts. The initial water shift does not turn into dehydration, and hydration status remains stable over time.

What this means on shift

Firefighters and police officers are already dealing with heat, heavy gear, long shifts, and inconsistent access to fluids. If creatine actually caused dehydration, we would expect to see more cramping, more heat illness, and more performance issues in the field.

We do not see that. In fact, evidence suggests creatine may help support thermoregulation and reduce cramping risk during intense work in hot environments². That is a pretty important detail when your job already pushes hydration to the limit.

Where You Need to Pay Attention

Creatine is not a substitute for hydration. You still need to stay on top of your fluid intake, especially on long or hot shifts. The supplement is not the problem, but poor hydration habits will catch up to you quickly.

Keep it simple:

  • Drink fluids consistently throughout your shift (92-125 oz)
  • Do not rely only on caffeine for energy and hydration
    • Coffee does count towards your fluid goals and will not cause dehydration
  • Stick to 3-5 grams per day or up to 0.10-0.12 g/kg/body weight to get the cognitive benefits²

If you are sweating through your gear on a call, dehydration is coming from fluid loss, not creatine.

The Bottom Line

Creatine does not dehydrate you. That is a myth that has stuck around longer than it should have. It increases water inside the muscle, not fluid loss, and it does not increase the risk of cramping or heat illness².

If you are skipping creatine because you think it will dry you out, you are avoiding one of the most well-researched and effective supplements available. Take it, stay on top of your fluids, and stop letting outdated gym myths drive your decisions.

Sources

  1. Antonio J, Candow DG, Forbes SC, Gualano B, Jagim AR, Kreider RB, Rawson ES, Smith-Ryan AE, VanDusseldorp T, Willoughby DS, Ziegenfuss TN. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition. 2021;18(1):13.
  2. Longobardi I, Solis MY, Roschel H, Gualano B. A short review of the most common safety concerns regarding creatine ingestion. Frontiers in Nutrition. 2025;12:1682746. 
  3. Ostojic SM, Grasaas E. Dietary creatine and hydration biomarkers in the general population: NHANES 1999–2023. Food Science & Nutrition. 2025;13
  4. Rawson ES. The safety and efficacy of creatine monohydrate supplementation: what we have learned from the past 25 years of research. Sports Science Exchange. 2018;31(186):1-6.

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