Cold sores are the resulting infection that comes from the herpes simplex virus; once this occurs, the virus tends to stay in the body for the rest of an individual's life, often making cold sores a relatively common appearance. The symptoms of a cold sore usually begin with an itching, burning, or tingling feeling on the location where the cold sore will eventually appear, such as around the mouth or nostrils. A sore throat and swollen glands might also appear as symptoms of a cold sore. Soon, a small fluid-filled blister, or grouping of blisters, will appear. Usually the blisters will dry up and disappear within ten days to two weeks.

The initial symptoms of a cold sore, known as the prodrome, include a slight tingling or burning that happens a day or two before the actual blisters show up. Some people also experience itching or even slight pain there. This occurs most frequently around the lips or the corners of the mouth, but it can also appear on the nostrils or inside the mouth, though this isn't as common. Putting medication on the area at the first symptoms of a cold sore can be helpful at preventing it from worsening.

Some people experience other symptoms of a cold sore throughout the body. A low fever, swollen glands in the neck, and a sore throat are not uncommon symptoms of a cold sore. Some people may find that the mouth feels sore, or that they experience some aches and pains in the body. These symptoms too will usually disappear when the actual cold sore appears.

The final symptoms occur when a blister, or frequently a group of blisters, appears on the mouth or nose. These blisters will be raised, red, and fluid-filled. After a few days they will begin to dry up, and will soon just appear as a slightly reddened mark on the face, which will eventually disappear. Typically, a cold sore will not cause a scar.

People who are prone to cold sores may get them repeatedly throughout the year, sometimes three or four times a year, or more. Some events can trigger a cold sore, such as another illness in the body, a period of high stress, or too much exposure to the sun. It is certainly possible to spread the herpes virus to others, so it is important for anyone experiencing the symptoms of a cold sore to learn ways to avoid spreading the virus.