Heat exhaustion is a type of heat-related illness. It can cause mild symptoms, however, heat exhaustion can be life-threatening if it progresses to a heat stroke, so you will have to closely monitor your symptoms.
Heat exhaustion can make you feel sick with symptoms such as:
- Heavy sweating
- Nausea
- Dizziness
- Cold, pale, clammy skin
- Headache
- Fast, weak pulse
- Muscle cramps
- Tiredness
- Weakness
- Fainting
Heat Stroke vs. Heat Exhaustion
If not treated, heat exhaustion can lead to heat stroke, a life-threatening medical condition that occurs when the body's cooling system stops working and the body’s core temperature increases to a point at which brain damage or damage to internal organs can occur (105° F [40.5° C] or greater).
Seek immediate medical help if you experience:
- Worsening symptoms
- Symptoms lasting more than one hour
- Inability to keep fluids down (vomiting)
- Deterioration of mental status (confusion or delirium)
- Shortness of breath
- Chest pain
- Abdominal pain
What Causes Heat Exhaustion?
Heat exhaustion is caused by exercising, working, or playing in very hot and humid weather.
Risk factors for developing heat exhaustion include:
- Inadequate fluid intake
- Dressing in too many layers of clothing or dark-colored clothing
- Wearing sports equipment such as heavy pads or helmets
- Direct sun exposure with no shade
- Alcohol consumption
- Low fitness level
- Being overweight or obese
- Lack of acclimatization to the heat
- Low potassium levels (hypokalemia)
- Age (toddlers and young children, the elderly)
- Fever
- Use of certain medications
- Diuretics
- Stimulants
- Lack of sleep
- Stomach illness
- Sickle cell trait
What Is the Treatment for Heat Exhaustion?
Treatment for heat exhaustion includes:
- Moving to a cool, shaded area or going into an air-conditioned building or car
- Drinking plenty of fluids
- Sports drinks with electrolytes may be helpful
- Avoid caffeine and alcohol
- Applying active cooling measures
- Sit in front of a fan
- Place a cold pack or cool compress on the neck, armpits, or groin
- Take a cool shower or bath
- Removing tight clothing or excess clothing or sports equipment
How Do You Prevent Heat Exhaustion?
When it is hot or humid, take steps to prevent heat exhaustion, such as:
- Don’t exercise, work, or play outdoors
- If you exercise, work, or play outdoors:
- Drink enough fluids, such as water or sports drinks
- Don’t drink large amounts in a short time, which can be harmful
- Keep activity levels low
- Take frequent breaks
- Perform activities early in the day, before it gets too hot
- Wear loose, lightweight clothing
- Drink enough fluids, such as water or sports drinks
Pay attention to symptoms of heat exhaustion and stop activity to cool down right away so symptoms do not progress to heat stroke, which is a medical emergency.
From 
Healthy Resources
https://www.cdc.gov/disasters/extremeheat/warning.html
https://orthoinfo.aaos.org/en/diseases--conditions/heat-injury-and-heat-exhaustion/
https://www.uptodate.com/contents/heat-stroke-the-basics?search=Heat%20Stroke&source=search_result&selectedTitle=1~66&usage_type=default&display_rank=1