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Sunburns vs Sun Poisoning vs Heat Stroke

Updated: Jul 9, 2023

Excess sun exposure is linked to several health risks. The skin plays a significant role in temperature regulation. When the body starts to overheat, the skin’s ability to regulate temperature diminishes. There is a distinction between sunburn, sun poisoning, and heat stroke. Read more...



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Photo: Wix

What are the main risks of a sunburn?

Excess sun exposure is linked to several health risks. The skin plays a significant role in temperature regulation. When the body starts to overheat, the skin’s ability to regulate temperature diminishes.

When exposed to extreme heat, signs of heat exhaustion may appear first. As temperatures rise, your skin tries to help cool down your body by producing sweat through sweat glands. The sweat will evaporate off the skin to cool it. This is almost like built-in air conditioning. As we heat up, we produce more sweat in an attempt to cool down further. With this fluid loss through the skin, we can start to experience signs of dehydration. The first signs of heat exhaustion are thirst, nausea, often dizziness, and an accompanying headache.

What is heat stroke?

Heat stroke is usually defined by the core body temperature exceeding 40 degrees Celsius. At this point other organs become involved. The central nervous system (CNS), kidneys, liver, and blood become involved.

These conditions can occur under a number of circumstances. People that are active, exercising, and exerting themselves but do not stay hydrated effectively can fall victim to heat exhaustion as can low activity level individuals such as the elderly, people with high blood pressure or diabetes, obesity, or alcoholism. The key contributing factor is heat. This is not exclusive to sun exposure as extreme heat from any source can trigger this response.

What is sun poisoning?

“Sun Poisoning” is technically not a medical term. It is a common way for patients to describe a scenario where a person experiences a severe sunburn through UV radiation followed by other systemic symptoms. If the sunburn is severe enough, systemic symptoms kick in that include fever, chills, and nausea. This is often due to the fact that with significant UV exposure, the skin can actually burn deeply leading to redness, swelling, and blistering. Our skin serves an important role in thermoregulation which is lost with a severe burn. This has less to do with overwhelmed sweat glands as seen with heat stroke or exhaustion. With sun poisoning the effect is because the sweat glands quite literally burned in addition to the rest of the exposed areas of skin.

From an appearance point of view, "sun poisoning" will still appear as severe sunburn. The term ‘sun poisoning’ as used non-clinically refers to the other symptoms experienced such as fever, chills, and nausea. When these symptoms develop will vary widely based on how much an individual can tolerate and how much of their body surface area is affected.

Are heat stroke and sunburn the same?

There is a technical difference between a heat stroke and a sunburn. Heat stroke only requires intense heat- there is no need for sun exposure to achieve this. Sunburns or sun poisoning require UV radiation to achieve- there is no need for heat. For example, it is not uncommon for skiers in subzero temperatures to experience a ‘sunburn’ as the UV is intense and magnified by fresh snow in spite of cold temperatures.

What is a sunburn?

Sunburns are the result of spending time exposed to UV radiation primarily from the sun. Artificial UV exposures can occur with tanning beds as well. Sun poisoning is a result of how extensive the sunburn is. Sunburns that are extensive and/or deep in the skin will make it more difficult for your body to regulate temperature. When this occurs, symptoms such as fever, chills, nausea, and malaise can kick in.

How long does it take to get a sunburn?

The amount of time it takes to cause a sunburn depends on multiple factors. The intensity of the UV, the amount of melanin in our skin, the use of any products, altitude, time of day, etc. all play a role.

Although it’s true that while we are on vacation we may spend prolonged time outdoors, the irony that I have noted after 15 years of performing thousands of skin cancer screenings annually is that most people are actually careful about wearing sunblock while on vacation. The vast majority of the sunburns I see in practice are the ones that occur when we simply are not thinking about sun exposure. Most of the burns I see in people who are otherwise careful about wearing sunblock occur in April or May while out watching a game, out for a walk or hike, etc. The temperatures are still somewhat cool so most are not thinking about wearing sunscreen. The UV intensity can still be significant resulting in a burn.

What is the best thing one could do to protect themselves from sunburn?

It is most important to consider a full sun safety plan. Sunblock, hats, sunglasses, and sun-safe clothing is key to protecting your skin effectively.

I recommend sunblocks with physical agents such as zinc or titanium. These ingredients block the sun. Chemical sunscreens absorb UV. The problem with this concept is that chemical sunscreens have a limit to how much UV they can absorb. Once they hit their maximal absorption the rest of the UV spills over to the skin.

Hats should be labeled as UV protective and ideally have a 3-inch brim all the way around. The problem with baseball hats (which most prefer) is that they do not protect the back of the scalp, the tops of the ears, and the neck.

Sunglasses should also be labeled as UVA and UVB blocking. The problem here is that tinted does not mean UV blocking. If a UV filter is not present then you can be placing your eyes at higher risk. The tint will cause your pupils to dilate and if the sunglasses do not block UV you may be getting more UV exposure than you realize!

Sun-safe clothing is the most important step in preventing sunburns and sun poisoning. The largest surface area of our body is covered by clothing and choosing the right clothing is key. Much like with sunglasses, clothing that is not labeled as sun protective may be giving you a false sense of security. The UPF of a white T-shirt can be as low as a 3! I have a patient who saw me after returning from Costa Rica- he applied sunblock all over except where his swim trunks were (he assumed his swim trunks would protect against UV). This is awful but the only place he burned was under his swim trunks! It is also important to use sun-safe clothing that does not use chemical finishes to achieve sun protection to minimize the chances that these special treatments wash out in the washing machine over time.

What are the long-term repercussions of unprotected sun exposure?

The main long-term consequence of unprotected sun exposure is the development of skin cancer. Skin cancer is considered an epidemic with one in five Americans diagnosed with skin cancer according to the Skin Cancer Foundation.

What are your tips for treating a sunburn?

Sunburns are treated like a burn - cool compresses, local wound care, drinking plenty of fluids, and taking NSAIDs. Aloe vera can help soothe the skin.

Is there anything else you think the average person needs to know about sunburns and sun exposure?

There are a number of factors that can make us more susceptible to sunburn.


In practice I see this go both ways. Traditionally the thought is that as we get older, our skin becomes thinner making us more susceptible to sunburns. However, in practice many of my patients state that they used to burn easily, and as they get older than tan easier. This may be the result of severe sun damage when younger which actually results in a leathery thickness to the skin as we get older. No matter which way you look at this the skin is at higher risk of skin cancer either from thinning that makes it burn easily or chronic sun damage that has led to a change in the texture of the skin that makes it high risk for skin cancer. Although I see sunburns in every age group, I do find that most cases of ‘sun poisoning’ I see are in younger patients.


Hormonal changes during pregnancy have been noted to lead to increasing sensitivity to the sun during pregnancy. This could result in both a higher chance of sunburn and/or pigment changes. It is important to note that taking precautions to avoid sunburn is important during pregnancy since ‘sun poisoning’ during pregnancy could impact the baby by core body temperature changes, fluid imbalances, and other burn-related changes in our blood work.


There are a number of what are referred to as “photosensitizing” medications. The common culprits are some antibiotics such as those in the tetracycline family, oral contraceptives, sulfa-containing medications, some antihistamines, NSAIDs, and some blood pressure medications, Many acne and anti-aging topicals also make our skin photosensitive.

If you are experiencing any discomfort or symptoms such as fever, chills, nausea, or malaise it is important to see your doctor. It is important to understand that our body’s response to a burn is not limited to the skin and can impact other organs.

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