Scenario: During a local half-marathon, officers respond to a 29-year-old female runner who collapsed near the finish line. Bystanders report she was running for more than four hours and had been drinking water at every aid station. On scene, she’s confused, vomiting, and her skin is cool and clammy. Friends add she didn’t eat or take electrolytes.
At first glance, this might look like heat exhaustion. But another possibility is exertional hyponatremia — a dangerous drop in sodium from drinking too much water without electrolyte replacement.
Why this matters for police officers
Police officers are often the first ones to reach a collapsed runner, protester or colleague working long hours in hot weather. You don’t have to make a medical diagnosis, but recognizing the warning signs and knowing what not to do can make a lifesaving difference until EMS arrives.
| RELATED: Tips for officers to guard against heat-related injuries
Heat exhaustion symptoms: What police officers may see
Heat exhaustion occurs when the body overheats and cannot effectively cool itself, typically due to high temperatures, strenuous activity and inadequate fluid intake. It’s part of the heat illness spectrum and may progress to heat stroke if untreated.
Here are common symptoms of heat exhaustion:
- Profuse sweating
- Pale, cool or clammy skin
- Fatigue or weakness
- Dizziness or lightheadedness
- Nausea or vomiting
- Headache
- Muscle cramps
- Tachycardia and mild hypotension
- Normal or slightly elevated body temperature
Immediate actions for police officers if heat exhaustion is suspected
- Stop activity immediately and move to a cooler, shaded environment
- Remove excess clothing and equipment to allow heat dissipation
- Hydrate with cool fluids, preferably with electrolytes
- Apply cool, wet cloths or misting fans to assist with evaporative cooling
- Rest until symptoms fully resolve — do not resume activity prematurely
- Monitor for worsening signs, such as confusion or cessation of sweating
Exertional hyponatremia symptoms: What police officers may see
Exertional hyponatremia results from excessive water intake that dilutes serum sodium levels, often during prolonged exertion. Sodium loss through sweat combined with overhydration disrupts electrolyte balance and cellular function.
Here are common symptoms of exertional hyponatremia:
- Headache
- Nausea and vomiting
- Bloating or abdominal discomfort
- Confusion or altered mental status
- Muscle cramps or weakness
- Swelling of hands, feet or face
- Seizures (in severe cases)
- Decreased coordination or stumbling gait
| RELATED: 10 ways officers can stay fit and safe in the summer heat
Immediate actions for police officers if exertional hyponatremia is suspected
- Move the person to shade or a cooler area
- Do not automatically give water — ask about how much they’ve already had
- If available, offer electrolyte-containing fluids only if they are alert and able to safely drink
- Monitor closely for confusion, worsening mental status or seizures
- Be prepared to assist with airway and breathing if the person becomes unresponsive
- Relay critical details to EMS: duration of activity, water intake, electrolyte/food intake, changes in mental status and any seizures observed
Heat exhaustion vs. exertional hyponatremia: Spot the differences
Both conditions can look alike at first — nausea, vomiting, weakness or collapse after long exertion. But there are a few key signs that can help officers tell them apart:
Bottom line for police
Unlike heat exhaustion, hyponatremia isn’t about overheating — it’s about too much water and not enough sodium. Giving more plain water can actually make things worse. Your role is to recognize the warning signs, limit further water intake, and provide EMS with a clear picture of the person’s exertion and fluid history. Early recognition of exertional hyponatremia vs. heat exhaustion can make the difference between rapid recovery and critical deterioration.
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