One friend told me about waves of nausea among the men at work. He suffered too.
That is one sign of dehydration. We stop being thirsty and start feeling nauseated. That is a major danger sign.
No longer sweating is even worse. If there is no need to use the restroom, or one is passing rusty radiator water, that is also dehydration.
The body must have enough water to carry out the most basic functions. That includes sweating for heat dispersal, but also cellular functions.
Herman Otten collapsed in his home after strenuous exercise in the heat, some years ago. I filled him in on these details. Some time later, Grace mentioned that someone scared him to death about dehydration, so he was more careful afterwards.
Dehydration can rapidly lead to heat stroke and death. It does not have to be horribly hot for that to happen. A pro football player died of heat stroke in Minnesota, during practice.
The Cure
First of all, people should really load up early on pure water, not sweet drinks or caffeine drinks. On a hot day, drinking a quart of water is a good idea. Keeping the water drinking all day is also necessary.
Nausea is a good reason to sit down and drink a quart of water slowly. The relief will be gradual in coming. After the nausea is over, thirst may still be there. Keep drinking.
This is routine in Phoenix, where the person at the door often says, "Hello, nice to see you, where's the bathroom?"
There is no shame in getting soaked with water on a hot day outdoors. When we viewed the cactus park in 105 weather, I stopped at each fountain and dumped water all over my shirt, front and back. Instant air-conditioning.
When we took my family through the park, I bought water for each person first. The tour guide asked where people were from. The natives all had water bottles. The others did not.
Crying babies in the heat may need to be washed down and hydrated. They probably suffer much faster than adults, due to the small bodies.