Recognising and Treating Dehydration and Heat Exhaustion
Dehydration and heat exhaustion are two of the most common and underestimated risks in warm-weather hiking. Even in the Alps—where temperatures are often moderate—long ascents, direct sun exposure, altitude and physical effort can quickly lead to fluid and electrolyte loss. If not addressed early, these conditions can progress to heatstroke, a medical emergency. Recognising symptoms early and applying proper first-aid measures ensures that hikers remain safe, stable and capable of making sound decisions throughout the trail.
Key Safety Principles and Common Risks
Dehydration occurs when the body loses more fluids than it takes in. Heat exhaustion happens when the body overheats and struggles to regulate temperature, often due to excessive sweating, inadequate hydration or prolonged sun exposure. Both conditions limit physical and mental performance, increasing the risk of mistakes, poor navigation, falls and impaired judgment.
Typical causes on the trail include:
Starting the hike already dehydrated
Not drinking regularly, waiting until thirsty
High temperatures or prolonged sun exposure
Insufficient electrolyte intake
Heavy backpacks and steep ascents
Dark clothing that absorbs heat
Rapid pacing without adequate breaks
Dehydration and heat exhaustion are highly preventable, but only if hikers monitor their hydration habits and pay attention to early warning signs.
Practical Advice & Early Warning Signs
Early Symptoms of Dehydration
Recognise these signs as soon as they appear:
Dry mouth and cracked lips
Headache
Dizziness or “lightheaded” feeling
Dark yellow urine
Fatigue and reduced pace
Muscle cramps
If ignored, symptoms may progress to nausea, confusion and difficulty walking.
Early Symptoms of Heat Exhaustion
Heat exhaustion may include:
Heavy sweating
Rapid heartbeat
Weakness or trembling
Pale or cool skin
Nausea
Fainting or near-fainting spells
These indicate that the body is struggling to cool down and needs immediate attention.
Practical Advice & Treatment Steps
Stop and Rest
At the first sign of dehydration or overheating, stop moving.
Overexertion raises body temperature rapidly, worsening symptoms.
Choose a shaded area, remove backpack weight and sit down comfortably.
Hydrate Slowly and Consistently
Drink water in small, frequent sips—rapid intake may cause nausea.
Use electrolyte tablets or rehydration salts to restore sodium, potassium and minerals lost through sweat. Electrolytes also prevent cramps and dizziness.
Aim to drink enough to make your urine light yellow.
Cool the Body
For heat exhaustion:
Move to shade or a cool area
Loosen or remove excess clothing
Wet a buff, hat or shirt and place it on the neck and forehead
Use airflow (wind or manual fanning) to enhance cooling
Never use ice or extremely cold water on overheated skin—it can cause shock.
Reduce Pace and Avoid Further Heat Exposure
After stabilising, continue the hike only if symptoms fully resolve.
If heat remains intense, adjust the plan:
Slow your pace
Take more frequent breaks
Stay hydrated proactively
Avoid exposed ridge sections during peak heat
When to Seek Help
Call for assistance if:
Symptoms worsen despite rest
Confusion or loss of coordination appears
No sweating despite heat (early sign of heatstroke)
The hiker cannot stand or walk without dizziness
Heatstroke is a life-threatening emergency requiring immediate medical attention.
Prevention Strategies
Hydrate Before, During and After
Start the hike fully hydrated.
During the trail:
Drink every 15–20 minutes, even if not thirsty
Use hydration bladders for easier sipping
Add electrolytes on longer or hotter hikes
Post-hike, continue hydrating to support recovery.
Wear Appropriate Clothing
Choose breathable, moisture-wicking and light-coloured layers.
A wide-brimmed hat helps reduce direct sun exposure.
Avoid cotton, which traps sweat and heat.
Time Your Hike Wisely
Begin early to avoid midday heat.
Plan shaded rest stops and avoid long breaks under direct sun.
Manage Effort
Pacing is crucial.
Short, steady steps reduce overheating more effectively than fast bursts of effort.
Use trekking poles to distribute energy.
Essential Gear
To prevent and treat dehydration and heat exhaustion, carry:
1.5–3 litres of water (depending on weather and distance)
Electrolyte tablets or rehydration powder
Wide-brimmed hat or cap
Lightweight, breathable layers
Buff or cloth for cooling
Sunglasses and sunscreen
Snacks rich in salt and carbohydrates
Hydration bladder or easy-access bottles
Dehydration and heat exhaustion are preventable conditions, yet they remain among the most common hazards hikers face in warm weather. By recognising early symptoms, hydrating strategically and taking immediate action, hikers can avoid severe complications and maintain physical and mental performance. With proper preparation, awareness and gear, the mountains become safer and more enjoyable even in the hottest months.
