Heat stroke is a potential condition that can arise when you become too dehydrated. At that point, mere water can’t bring back all the electrolyte fluids that help keep your body temperature regulated. If you’re sweating and then stop and start to feel extreme thirst or tiredness, it’s time for a water break. If you’re working hard, about a liter of water every hour is recommended to help maintain the body’s optimal function.

When severe dehydration kicks in, you may start to notice rapid heartbeat and breathing, a fever, high agitation or sleepiness, sunken eyes, and, in the worst-case scenario, delirium, unconsciousness or hallucinations. That’s when you need to seek medical professionals, who can administer intravenous fluids and help monitor your condition to bring you back.

How to Tell if Dehydration Is Setting in

Beyond thirst, keep a close eye on your urine. It should be light-colored under normal hydration situations. If it is dark yellow in color or even amber, there’s the potential for trouble. It’s suggested you drink a sports drink like Gatorade at that point to restore the balance in your hydration.

Of course, children and the elderly may have more severe reactions when dehydrated, and many won’t manifest the symptoms until hours after the fact. Anyone who is unusually irritable or much less active than they usually are after an afternoon in the sun should be watched. If diarrhea or black stool is present, and if the person has trouble keeping fluids down, it’s time to visit the emergency room.

Dehydration is a sneaky condition that doesn’t necessarily announce itself in major ways. Drying out the system, which is what dehydration essentially does, is a gradual process and people who are busy or distracted may disregard it. This is particularly true when traveling or camping, where access to regular water may be restricted by circumstances.

Beyond activity, it’s good to watch out for other things that can cause dehydration.