5 Conditions Triggered by Excess Sun Exposure

The Problem With Getting Too Much Sun

In This Article

Most people like to spend time outdoors on sunny days, but too much sun exposure can have serious consequences, ranging from painful sunburns to potentially life-threatening sunstroke.


Sunburn is a common skin injury caused by excessive exposure to ultraviolet (UV) radiation from the sun. The injury is triggered by an inflammatory response as UV radiation directly damages DNA in skin cells. When a cell's DNA is irreparably damaged, it will undergo apoptosis (cell death) and be quickly shed, leading to the peeling and flaking of skin.

Common symptoms of sunburn include reddish skin, pain, swelling, fatigue, and hot skin temperatures. There may also be rash, nausea, fever, dizziness, and chills in more severe cases; contact a medical professional if these symptoms occur. Second-degree sunburns can manifest with blistering, oozing, dehydration, edema (tissue swelling), and fainting.

Sunburn can begin after only 15 minutes of direct sun exposure. Pain and redness tend to be greatest during the first six to 48 hours.

Sunburns do not only occur on hot summer days. Prolonged exposure even on snowy or overcast days can lead to burning. Preventive measures including sunscreen and sun-protective clothing can greatly reduce your risk.

Over time, excessive sun exposure can lead to skin damage, premature skin aging, and skin cancer. In fact, a prior history of severe sunburn increases the risk of squamous cell carcinoma by 2.4 fold and the risk of melanoma by 1.5 fold.

You can treat mild sunburn with a cool bath or shower, cool compresses, and an over-the-counter moisturizing cream. For pain, a nonsteroidal anti-inflammatory drug (NSAID) like Advil (ibuprofen) or Tylenol (acetaminophen). If blisters form, do not break them.


Dehydration is the depletion or imbalance of fluids or electrolytes that interferes with the normal body functions. It occurs when the loss of body fluids exceeds the intake of fluids, usually on hot days when you are overexerting yourself.

Most healthy people can tolerate between a 3% to 4% loss of body water without symptoms. After 5%, dizziness, headaches, and fatigue can develop. As the water loss exceeds 10%, severe symptoms can develop, including decreased urination, confusion, and seizures.

Mild dehydration can usually be resolved by drinking water or an electrolyte-rich sports drink. The best way to avoid dehydration is to drink water before you get thirsty, especially if you plan to be in the sun for a long period or are overexerting yourself.


The opposite problem of dehydration is a condition known as hyponatremia (sometimes referred to as "water intoxication"). Hyponatremia can occur when you lose a lot of water through sweat but fail to replace lost sodium when you rehydrate.

People often think of dehydration as the loss of water when, in fact, it is also characterized by an imbalance of electrolytes. Hyponatremia can occur during endurance sports when you lose too much fluid but only drink water. Unless you replace the lost sodium, you can begin to feel the effects of the depletion, including:

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

Mild hyponatremia can usually be resolved by drinking an electrolyte-rich sports drink. Severe cases usually require a 3% saline solution delivered intravenously (into a vein) by emergency medical personnel.

Heat Exhaustion

Dehydration, when coupled with prolonged sun or heat exposure, can cause heat exhaustion. By definition, heat exhaustion occurs when the body's core temperature rises above 98.6° F (30° F) but not beyond 104° F (40° C). It typically occurs on hot, humid days when you are overexerting yourself.

Dehydration and obesity greatly increase the risk of heat exhaustion as does alcohol, caffeine, and certain drugs (such as diuretics, antihistamines, beta-blockers, alcohol, ecstasy, and amphetamines). Infants and the elderly are at greatest risk as they tend to have impaired thermoregulation (the ability of the body to adjust to climate changes).

Common symptoms include dizziness, headache, nausea, thirst, weakness, high body temperature, profuse sweating, decreased urination, and vomiting.

If someone you know has heat exhaustion, move them to a cool space and remove any excess clothing. You can bring down their body temperature by fanning them or placing cool, wet towels on their skin. Offer water or a sports drink if they can keep fluids down. If dizziness occurs, lie them on their back and elevate their feet.

If first aid measures fail to provide relief within 15 minutes, call 911 or seek emergency medical care. If left untreated, heat exhaustion can lead to heatstroke.


Heatstroke, also known as sunstroke, is a more severe form of heat exhaustion in which the body's core temperature exceeds 104° F (40° C). It causes over 600 deaths in the United States each year, either because of excessive exertion in hot temperatures (referred to as exertional heatstroke) or certain conditions that impair thermoregulation (non-exertional or "classic" heatstroke).

Common causes of classic heatstroke include younger age, older age, alcohol, stimulants, and certain medications. Death from heatstroke frequently occurs when younger children or the elderly are left in parked cars in direct sunlight, where temperatures can climb to 124° F to 153° F (51° C to 67° C).

Symptoms of heatstroke are more profound than heat exhaustion but can differ based on whether you have exertional or classic heatstroke. For instance, sweating is characteristic of exertional heatstroke but typically absent with classic heatstroke. Other symptoms may include:

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

As symptoms advance, the skin can suddenly take on a bluish tinge as blood vessels begin to narrow and restrict blood flow and oxygen exchange. If left untreated, heatstroke can lead to organ failure, rhabdomyolysis (the breakdown of skeletal muscle), and death.

Heatstroke is treated as an emergency and involves the rapid cooling of body temperature, oral and IV rehydration, and standard resuscitation measures by trained medical professionals.

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