Some symptoms of heat exhaustion and heatstroke are similar, but these conditions are also very different. It is important to know that while heat exhaustion isn’t as severe as heatstroke, it shouldn’t be taken lightly because it can easily progress to heatstroke.
Heat cramps are the earliest signs of a heat illness. They are painful muscle spasms that occur when someone has become dehydrated and has lost nutrients and minerals (electrolyte loss) from excessive sweating. Heat cramps are commonly felt in the arms, legs, back, and abdomen.
Heat cramps are caused by heat, illness, and activity. They can come on suddenly or gradually. They often start as muscle twitches and are unnoticeable until they become severe.
Heat Exhaustion Symptoms
Heat exhaustion occurs after a person has been exposed to high temperatures and is experiencing dehydration.
According to the Centers for Disease Control and Prevention (CDC), the most common signs of heat exhaustion are:
- Heavy sweating
- Cold, pale, and clammy skin
- A fast or weak pulse
- Nausea and/or vomiting
- Muscle cramps
- Weakness or fatigue
- Fainting or near fainting
Additional symptoms might include dark yellow urine (a result of dehydration) and confusion.
Heatstroke is the most serious form of heat illness and is considered a medical emergency. It often occurs after milder heat illnesses, including heat cramps, heat syncope (fainting), and heat exhaustion. It can also occur in people who have no previous signs of heat illness.
Heatstroke results when there is prolonged exposure to high temperatures in combination with dehydration. This leads to a failure in the body’s internal temperature control. Heatstroke occurs when the body’s temperature reaches 104 degrees.
Having that high core body temperature affects the central nervous system, causing the following symptoms:
- Nausea and vomiting
- Seizures (uncontrolled electrical activity in the brain)
- Confusion and disorientation
- Loss of consciousness or coma
Additional symptoms of heatstroke include:
- Dry skin that doesn’t sweat or profuse sweating
- Low urine output
- Rapid breathing or fast heart rate