Heat Syncope: Fainting From the Sun and How to Treat It

Heat syncope can be described as passing out from overheating. Excessive heat can produce many health complications, including heat exhaustion and heat stroke. Your body can become overheated due to a severe illness that causes a fever or because of the temperature of your surroundings.

This article describes heat syncope, the risks, how to keep yourself safe in the heat, and what to do if you or someone else experiences signs of health complications from heat.

Heat Syncope: Symptoms Before and After Fainting

Syncope is fainting, and it has many causes. A person can pass out without much warning, but sometimes there are warning signs.

Signs and symptoms that you or someone else might experience before syncope include:

• Flushing, redness of the face, neck, or arms (although can be pale)
• Feeling dizzy or light-headed
• Feeling very hot or suddenly sweating
• Muscle cramps
• Confusion

Syncope can appear as slumping down to a lying position while sitting, or it can cause falling to the ground from a sitting or standing position. A person may appear to be in and out of awareness of what’s going on around them during the syncope episode.

Many people wake up a few seconds after fainting, but this doesn’t always happen. A person who wakes up after a syncope episode may be somewhat confused and might only have a partial recollection of what happened in the minutes prior to fainting.

Why Does Heat Make People Pass Out?

Syncope is one of the ways that the body responds to extreme physical demands or sudden changes in blood pressure. Normal body temperature is 98.6 degrees F. Usually, your body can adjust when you have a fever or when you are exposed to slight changes in outside temperatures.

Overheating due to environmental temperature, direct sun exposure, being overdressed, or a fever can disrupt the body’s regulatory mechanisms. Hyperthermia is an internal body temperature above 100.4 degrees F. It may cause changes in blood pressure, heart rate, and respiratory rate, or a hormonal imbalance. Any of these changes may cause a person to pass out.

Vasovagal syncope, which is a more common cause of passing out. It can occur due to extreme emotional distress, prolonged standing, heat, bearing down when using the toilet, or the sight of blood for some people. It leads to disruptions in blood pressure, heart rate, hormone release, and/or breathing.

During a Heat Syncope Episode

If someone experiences a heat syncope episode, you should call for medical help. These episodes can resolve quickly, but overheating may also cause serious complications—such as organ failure. After an episode of syncope, a person may need medication, intravenous fluids, or oxygen supplementation.

Additionally, a person who experiences a heat syncope episode might have a health risk factor that makes them susceptible to reacting to heat exposure this way.

First Aid

While you’re waiting for emergency responders to arrive to help someone undergoing syncope, you should make sure that person is not in danger of falling or drowning. Keep them away from water or stairs, potentially helping get them to the ground gently so they won’t fall.

Additionally, place a cool pack or cool blanket anywhere on their body to help cool down their temperature.

What to Avoid

If someone has experienced syncope, do not cover their nose or mouth. It is not safe to give them food or drink, unless they are completely alert and able to safely swallow voluntarily. Do not use ice to cool them down, but it is OK to use a cooling pad or a cooling blanket.

Treatment After Heat Syncope Episode 

You might need medical attention for an episode of passing out from the heat. Treatments given in a medical setting can include a cooling blanket, fluids, ice bath immersion, and anti-seizure medication.

After you’ve recovered from a heat syncope episode, you may need medical attention to make sure that you are stable. You may have your temperature monitored, as well as your oxygen level, blood pressure, pulse, respiratory rate, and blood glucose (sugar).

You might also have diagnostic tests to see if you have any risk factors for syncope. 

Tests to identify risk factors may include:

• Blood tests: Depending on your overall health, you might need an evaluation to identify whether you have an infection, anemia (low blood cell count or function), or signs of organ disease (such as kidney disorders or thyroid disease). 
• Blood pressure: Hypotension (low blood pressure) can predispose you to syncope
• Electrocardiogram (ECG or EKG): This noninvasive test evaluates your heart rate and rhythm and can pick up on some irregularities that could predispose you to syncope. 
• Echocardiogram: This noninvasive test examines the appearance of your heart as it moves and can detect some functional and structural heart abnormalities.

If your test results show that you have any risk factors for recurrent syncope, you would need treatment for your underlying health condition.

How to Prevent Future Fainting From Sun 

Some people experience heat-associated syncope because of extreme heat exposure, even without risk factors. 

Some tips to prevent fainting from the sun or heat are:

• Be mindful of the amount of time that you are exposed to the sun—use an umbrella, or wear a visor when you are out in the heat.
• Stay hydrated when you’re exposed to the heat, especially if you are exercising.
• Don’t fall asleep out in the sun.
  
• Dress in layers if you will be exposed to fluctuating temperatures (such as on an airplane) so that you won’t get overheated.
• Check your temperature if you have an illness, and take medication to lower a fever as directed by your healthcare provider.
• Limit your time in a hot tub, sauna, or steam room and make sure you step out for at least a few minutes, approximately every 15 minutes.
• Limit your time outdoors when there are heat warnings.

If you have risk factors for heat syncope, you need to pay extra consideration to these tips. For example, some people may be advised to completely avoid hot tubs. Talk to your healthcare provider to get advice about whether you need to take special precautions regarding heat exposure.

Summary 

Heat syncope or passing out due to and excessively hot body temperature or environment can be dangerous. It's important to take measures to avoid heat related illness, especially if you are at a higher risk due to an underlying health condition.

If you or someone you know is experiencing signs of passing out due to heat, such as dizziness or confusion, it's important to try to get to a more tolerable temperature. If you are around someone who experiences syncope, get medical attention as soon as possible.