Cold sores are painful blisters in or around the mouth. These sores are a marker of the herpes simplex virus (HSV), which comes in two forms, HSV-1 and HSV-2. Anyone with either type of HSV is at risk of developing cold sores, but type one is most often responsible.

There are several things that can cause diarrhea. Most of the time, diarrhea is simply your gut's way of getting rid of a harmful invader, like a bacteria or virus.

Some fevers are serious enough to seek medical attention, while others benefit from soothing home treatments. Find out the difference, along with other fever facts.