Sun Poisoning looks just like a sunburn, really read, hurts to touch or rub. However, Poisoning can't be diagnosed from just the look of the burn itself, but the symptoms that come with it. *fever, *dizziness, *disorientation, *flu-like symptoms, *possible mood swings, *dehydration(running tears, slobbering, sweating). All of these are very dangerous symptoms and need to be addressed immediately for example taken to the Emergency Room and be treated for the symptoms ESPECIALLY the dehydration which could lead to more serious bodily harm.
It's pretty much the same as getting sunburned, but even more severe. When you're skin gets so burnt that it blisters, that would be sun poisoning. Lather on the SPF as much as possible!