7. Scarlet fever
One thing that’s especially scary about scarlet fever is that it sometimes develops as the result of a common infection we know as strep throat. Fortunately, it’s not a particularly common development but when it does happen it is vital to seek treatment immediately before it can cause serious damage to the heart, central nervous system, kidneys, and lungs. As the name suggests, scarlet fever is characterized by a red rash that often appears on the face and neck and can spread to the entire body.