Every June for three years, I did the same thing: quietly stopped my creatine before the hot weather arrived, convinced I was protecting myself from dehydration. A sports doctor at a training camp in Portugal put an end to that habit in about ninety seconds. Creatine doesn’t pull water out of your system, she told me. It pulls water into your muscle cells, and that’s the opposite problem from the one I’d been worrying about for years.
The confusion makes sense once you see where it started. Creatine changes how your muscles handle water, but the direction of that change got scrambled somewhere between the lab and the gym floor.
Key takeaways
- A decade-old myth about creatine causing summer dehydration shaped training habits—but was it ever actually proven?
- What happens inside your muscles when creatine enters the picture might be the complete opposite of what you’ve heard
- Heat-stress research exists on this exact scenario, and the results surprised everyone who’d been avoiding creatine in warm weather
Where the dehydration myth actually came from
Back in the 1990s and early 2000s, a handful of case reports linked creatine supplementation to muscle cramping and heat-related illness in athletes. American college sports bodies grew cautious, and some even restricted its use for a period. The logic seemed sound on the surface: creatine affects water balance, hot weather already stresses your fluid levels, so combining the two sounded risky.
What those early reports didn’t establish was causation. They were observational, often involving athletes who were already cutting weight, training in extreme heat, or under-hydrating for other reasons entirely. Creatine became the convenient explanation rather than a proven one.
Later research took a closer look and found something rather different. A position stand from the International Society of Sports Nutrition, which reviewed the accumulated evidence on creatine safety, concluded there’s no reliable data showing creatine increases the risk of cramping, dehydration or heat illness. If anything, the opposite pattern started showing up in controlled trials.
What’s actually happening inside your muscle cells
Creatine is osmotically active, meaning it draws water toward itself wherever it sits in the body. Once you supplement, more creatine ends up stored inside your muscle fibres, and water follows it there. That’s an intracellular shift, water moving into cells, not out of your bloodstream or your tissues generally.
Total body water actually tends to rise slightly during the loading phase of creatine use, typically by a small percentage of body mass in the first week or so. That’s stored inside muscle tissue, plumping cells rather than depleting them. Athletes sometimes notice this as a temporary weight increase on the scale and mistake it for bloating or fluid retention gone wrong. It’s neither. It’s your muscles holding onto more of their own hydration reserve.
Glycogen storage plays a supporting role here too. Creatine supplementation is associated with increased glycogen content in trained muscle, and glycogen itself binds water molecules as it’s stored. The combined effect is muscle tissue that’s better hydrated at a cellular level, not worse.
The heat research nobody talks about
Here’s the part that surprised me most. Several controlled studies have specifically tested creatine supplementation under heat stress, exactly the scenario I’d been avoiding it for. Findings from this research generally show no adverse effect on markers like heart rate, core temperature or sweat rate during exercise in hot conditions.
Some researchers have gone further and proposed that the extra intracellular water creatine encourages could offer a mild protective buffer during exercise in heat, essentially giving muscle cells a slightly larger fluid reserve to draw on. This isn’t settled science, and I wouldn’t want anyone reading this to treat creatine as a heat-illness prevention strategy. But it does flip the original worry on its head. The compound I’d been ditching every summer out of caution turns up in heat-stress trials looking, at worst, neutral.
None of this means fluid intake stops mattering once creatine enters the picture. It just means the mechanism I’d assumed, creatine draining your body’s water reserves, doesn’t match what actually happens physiologically.
What I do differently now
I kept my daily dose steady through the warmer months this year, typically the standard maintenance amount most guidance suggests, taken with food rather than on an empty stomach during long training days. The one genuine adjustment worth making in summer isn’t cutting creatine, it’s simply drinking enough water to support the extra intracellular storage your muscles are now holding onto. That’s a sensible habit regardless of what supplements you’re taking, heatwave or not.
A few practical points I’d pass on to anyone reconsidering their own summer routine:
- Consistent daily dosing works better than stopping and restarting, since your muscle creatine stores take time to build back up
- Pairing your dose with a proper glass of water, rather than a token sip, supports the fluid shift happening in your cells
- Training in genuinely extreme heat still calls for the same sensible precautions anyone would follow: shade, electrolytes, and listening to how your body responds, creatine or not
If you’ve got existing kidney concerns, are pregnant, or take regular medication, that’s a conversation for your GP before starting or continuing any supplement, creatine included. The research on healthy adults is reassuring, but reassuring isn’t the same as universal.
What sticks with me most from that conversation in Portugal wasn’t the correction itself, it was realising how a decade-old, poorly sourced worry had shaped my habits without me ever checking the underlying research. Three summers of unnecessarily pausing a supplement that was working perfectly well, based on a myth that had already been quietly dismantled by the people who study this for a living.