“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 sun burn 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 a 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.
It is important to note that those there is a technical difference between a heat stroke and sun burn. 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.