Heat related illness: How to keep your cool

Wynne Armand, MD

Contributing Editor

The summer season is waning but we’re not done with the heat. Hot and humid weather can bring a host of heat-related problems: heat cramps, heat rash, heat exhaustion, heat stroke…. It’s helpful to be aware of these issues, especially as we experience changes in the climate with humidity or rising temperatures. There have been several studies which have documented an uptick in emergency department visits and hospital admissions for conditions like dehydration, electrolyte imbalances, and other types of heat related illness during times of high heat. Persons who are particularly at risk are the very young and old, those who do prolonged exertional work outdoors, and intense athletes.

Getting overheated: The cause of heat related illness

Our bodies are not well-equipped to withstand large increases in our core body temperature, which is usually around 98.6 ˚ F (37˚ C). With heat stroke, core body temperatures may rise dangerously to around 103˚ to 104˚ F (39.4˚ to 40˚ C). If you have a concern about overheating, be sure to check a rectal temperature, as other methods like oral, axillary, or tympanic measurements can be inaccurate in these situations.

Our bodies have a number of mechanisms to help us cool down. One of the most important is evaporation through sweat, but this mechanism becomes less efficient in high humidity. Also, when we are dehydrated or when we are not accustomed to exertion in the heat, cooling off through evaporation becomes more challenging.

Furthermore, there are a number of medications that impair our bodies’ mechanisms for cooling off, like antihistamines, anticholinergics, decongestants, diuretics, stimulants, and some blood pressure pills, to name a few.

Signs and symptoms of heat-related illness vary. Dehydration may cause feelings of thirst, dizziness, and fatigue. Heat stroke, which needs urgent medical attention, may include hot or flushed skin, a fast heart rate, headache, nausea, dizziness, confusion, or loss of consciousness.

3 key questions about hydration

1.   How much should you hydrate? If you know you are going to be exerting yourself in the heat, start your hydration beforehand, so you start with a “full tank.”

2.  Is it possible to “overhydrate”? Yes. Best to speak with your doctor if you have a medical condition that requires you to be on diuretics or a fluid restriction. Also, though not common, drinking too much water can cause hyponatremia, or a low sodium concentration in the blood. This can be quite serious when it does happen, leading to symptoms like nausea, vomiting, headache, muscle cramps, confusion, and seizures. Hyponatremia is more likely to happen with athletes who sweat a lot, losing salt and water, but then replace the sweat by drinking only water, causing a diluting effect. Sport electrolyte drinks (which can be high in sugar and calories) are an option, but usually not necessary if you hydrate with water while having regular meals or salt-containing snacks.

3.  How do you know if you are getting enough fluids? Well, if you feel thirsty, you may already be dehydrated. Another telltale sign of dehydration is making less and darker urine, as opposed to normal amounts of light yellow urine.

10 tips for avoiding heat related illness

  • Plan to take it easy, especially if you are not used to exerting yourself in the heat and humidity.
  • Seek shade or cool areas and avoid prolonged exposure to the heat.
  • Protect yourself from sunburns.
  • Wear light, loose, reflective clothing.
  • Stay hydrated and avoid alcohol and caffeinated drinks.
  • Cool down with a cold bath or shower.
  • Dampen your clothes or apply wet towels while cooling off with an electric fan.
  • Use ice packs, especially on the neck, underarms, or groin near the main blood vessels.
  • If you feel ill and your symptoms are severe, seek prompt medical attention.
  • And remember, check in on anyone you think is at risk and might be more vulnerable!

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