Symptoms resemble those of shock and include: 

• Weakness.
• Sweating.
• Dizziness.
• Nausea.
• Fast breathing.
• Heavy sweating. 
• Dry tongue.
• Thirst.
• Rapid, weak heartbeat.
• Low blood pressure.
• Cool, moist, pale skin.
• Low fever.
• Heat cramps and muscle fatigue.
• Lost of appetite.
• Headache.
• Exhaustion. 

What to do when suspecting heat exhaustion?

• If achievable, move the person out of the sun and into an air-conditioned space. Otherwise, try to provide them with as much shade as possible.
• Lay the person down and slightly raise legs.
• If you can, remove the person's clothing or loosen. 
• If possible, carefully cool the person's body by spraying or sponging him or her with cool water.
• Give the person cool water or juice.
• Fan air onto the person.
• Monitor the person carefully because heat exhaustion can easily become heatstroke.

Call for emergency medical assistance (Dial 997) if symptoms don’t clear after 30 minutes or there is high fever that’s more than 38.9 C accompanied with fainting, confusion or seizures.