5 Conditions Triggered by Excess Sun Exposure

The Problem With Getting Too Much Sun

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Most people like to spend time outdoors on sunny days. Too much sun exposure, however, can have serious consequences. These can include:

This article looks at some of the consequences of spending too much time in the sun. It also discusses some of the ways sun-related conditions can be treated.

Woman with sunburnt back

Science Photo Library / Getty Images


Sunburn is a common skin injury. It is caused by excess exposure to ultraviolet (UV) radiation from the sun. The injury happens when UV radiation directly damages the DNA in skin cells, triggering an inflammatory response. The damaged cells die and shed, which is what causes the peeling and flaking of skin.

Sunburn Symptoms

Common symptoms of sunburn include:

  • Reddish skin
  • Pain
  • Swelling
  • Fatigue
  • Hot skin temperatures

Pain and redness tend to be greatest during the first six to 48 hours.

sunburn on arm

DermNet / CC BY-NC-ND

In severe cases, you may also have:

  • Rash
  • Nausea
  • Fever
  • Dizziness
  • Chills

If these symptoms occur, contact your doctor.

Second-degree sunburns are more serious. Symptoms include:

  • Blistering
  • Oozing
  • Dehydration
  • Edema, or swelling of tissue
  • Fainting

When You're at Risk

Sunburns don't only happen on hot summer days. You can get a sunburn even on a snowy or overcast day. You can reduce your risk by using sunscreen and sun-protective clothing. Remember that it only takes 15 minutes of direct sun exposure to cause a sunburn.

Over time, excessive sun exposure can cause long-term problems, including:

A history of severe sunburn gives you a 2.4-fold increase in your risk of squamous cell carcinoma and a 1.5-fold increase in the risk of melanoma.

Treating Sunburn

Mild sunburn can be treated at home with a cool bath or shower, cool compresses, and an over-the-counter moisturizing cream. For pain, you can take an over-the-counter pain reliever like Advil (ibuprofen) or Tylenol (acetaminophen). If blisters form, do not break them.


Dehydration occurs when your body loses too many fluids or electrolytes. This can interfere with your normal body functions. On hot days, you may become dehydrated when you're not taking in as many fluids as you're losing.

Symptoms of Dehydration

Most healthy people can tolerate between a 3% to 4% loss of body water without symptoms.

After 5%, you may develop:

  • Dizziness
  • Headaches
  • Fatigue

As the water loss exceeds 10%, severe symptoms can develop, including:

  • Decreased urination
  • Confusion
  • Seizures

Treating Dehydration

Mild dehydration will usually resolve when you drink water or an electrolyte-rich sports drink.

The best way to avoid dehydration is to drink before you get thirsty. This is especially important if you plan to be in the sun for a long period or are overexerting yourself.


Dehydration happens when your body loses more fluids and electrolytes than it takes in. You can avoid dehydration by drinking an electrolyte-rich sports drink before you start to feel thirsty.


The opposite of dehydration is hyponatremia. This is sometimes also called "water intoxication."

Dehydration isn't just water loss. When you're dehydrated, your electrolytes also become imbalanced. Hyponatremia can occur when you lose a lot of water through sweat but you don't replace lost sodium when you rehydrate.

Hyponatremia Symptoms

Hyponatremia can happen when you lose too much fluid but only drink water. Unless you replace the lost sodium, you may experience the following symptoms:

  • Headache
  • Fatigue
  • Lethargy
  • Loss of appetite
  • Irritability
  • Muscle weakness
  • Cramps
  • Confusion

Treating Hyponatremia

Mild hyponatremia will usually resolve when you drink an electrolyte-rich sports drink. Severe cases need to be treated by emergency care providers. These cases are usually treated with a 3% saline solution delivered into a vein.


Drinking too much water when you're dehydrated can cause water intoxication. To avoid this, replace fluids with an electrolyte-rich sports drink.

Heat Exhaustion

Dehydration with prolonged sun or heat exposure can cause heat exhaustion. This happens when the body's core temperature rises above 98.6° but not above 104°. It typically occurs on hot, humid days when you're overexerting yourself.

Risk of Heat Exhaustion

Dehydration and obesity greatly increase the risk of heat exhaustion. Other factors that can contribute include:

Babies and the elderly are at greatest risk. This is because their bodies aren't as good at adjusting to temperature changes.

Heat Exhaustion Symptoms

Common symptoms include:

  • Dizziness
  • Headache
  • Nausea
  • Thirst
  • Weakness
  • High body temperature
  • Profuse sweating
  • Decreased urination
  • Vomiting

Treating Heat Exhaustion

If someone you know has heat exhaustion:

  • Move them to a cool place
  • Remove any excess clothing
  • Bring down their body temperature by fanning or placing cool, wet towels on their skin
  • Offer water or a sports drink if they can keep fluids down
  • If dizziness occurs, have them lie on their back and elevate their feet

If symptoms don't improve after 15 minutes, call 911 or seek emergency medical care. Left untreated, heat exhaustion can lead to heatstroke.


Heatstroke is also known as sunstroke. It is a more severe form of heat exhaustion. When you have heatstroke, your body's core temperature exceeds 104°. Heatstroke causes more than 600 deaths in the United States each year.

There are two different types of heatstroke:

  • Exertional heatstroke, caused by excessive exertion in hot temperatures
  • Non-exertional or "classic" heatstroke, caused by conditions that interfere with your body's ability to regulate its temperature

Causes of Heatstroke

Common risk factors for classic heatstroke include:

  • Younger age
  • Older age
  • Alcohol use
  • Stimulant use
  • Use of certain medications

Death from heatstroke often occurs when younger children or the elderly are left in parked cars in direct sunlight. On a hot day, temperatures inside a parked car can quickly climb to 124° to 153°.

Heatstroke Symptoms

Symptoms of heatstroke are more profound than heat exhaustion. They can differ based on whether you have exertional or classic heatstroke. For example, sweating is typical with exertional heatstroke but not with classic heatstroke.

Other symptoms may include:

  • Rapid breathing
  • Fast, weak pulse
  • Nausea and vomiting
  • Confusion or delirium
  • Hostility
  • Intoxication-like behavior
  • Fainting and unconsciousness
  • Seizures, especially in children

As symptoms advance, skin can suddenly take on a bluish tinge. This happens as blood vessels narrow and restrict blood flow and oxygen exchange.

Left untreated, heatstroke can lead to:

  • Organ failure
  • Rhabdomyolysis, the breakdown of skeletal muscle
  • Death

Treating Heatstroke

Heatstroke is an emergency. Treatment involves:

  • Rapidly cooling the body
  • Oral and IV rehydration
  • Standard resuscitation measures by trained medical professionals


Heat stroke is the most severe form of heat exhaustion. It can happen when you overexert yourself in hot weather or are exposed to extremely hot conditions. If you suspect heatstroke, seek medical care at once.


Too much time in the hot sun can lead to a number of health conditions. This includes sunburn, dehydration, hyponatremia, heat exhaustion, and heatstroke.

You can avoid these conditions by taking the right precautions. Use sunscreen and sun-protective clothing. Replace lost fluids and electrolytes with a sports drink. Learn to recognize the symptoms of heat exhaustion and heat stroke and avoid exerting yourself in hot, humid weather.  

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.