Heat stroke is an immediate, life-threatening emergency!
- High body core temperature (over 105°F).
- Hot, dry, red skin.
- No perspiration (most notable, this is the point where the body went from heat exhaustion to heat stroke).
- Very rapid and strong pulse.
- Move victim to cool environment.
- Remove perspiration-soaked clothing.
- Loosen tight or restrictive clothing.
- Apply cool, wet cloth to the skin, changing frequently.
- Keep victim still and prone.
- Talk to the victim to keep them from going into a coma.
- Give the victim cool water to drink.
- Fan the victim or provide air circulating equipment.
- Do not give victim any alcohol, which is a blood-thinning agent, or caffeine, which is a diuretic.
- Contact medical professionals as soon as possible, especially if victim refuses water, vomits or is unconscious.
- Immersing in cold water can lead to shock. If the situation is serious enough, you can use cool (not cold!) water, especially if the victim is a child. Only put a few inches of cool water in the tub and use a cup to pour over exposed skin.
From US Navy boot camp training. This helped me once, when a neighbor's kid went into heat stroke.