Cold sores are a type of lesion that typically appears on the outside of the lips. Fever blisters and cold sores are two descriptions for the same type of sore. The sores are caused by infection with a type of herpes virus, called herpes simplex virus type 1. Cold sores are different from canker sores, a type of sore that appears on the inside of the mouth; canker sores are a type of ulcer and they not caused by a viral infection.
Herpes simplex virus type 1 is similar to the herpes simplex virus that causes genital herpes, a sexually transmitted infection. Cold sores are usually caused by herpes simplex virus type 1 and genital herpes is caused by herpes simplex virus type 2. However, the sores from both types of viruses can spread to other areas of the body when a person is contagious. Herpes simplex virus infection is not curable; the virus goes into a dormant state when a person is not having an outbreak. Herpes simplex outbreaks can be triggered by changes such as increased stress, hormonal fluctuations, sun exposure and fatigue. Having a fever from another illness can also trigger a herpes simplex virus outbreak, which is why cold sores are also called fever blisters.
Cold sores appear as small red sores around the outside of the mouth. The sores can be painful, and before they appear a person may feel a tingling sensation in the area for a day or two. The sores may fill with fluid and become blisters. Fever blisters usually last for about 1 to 2 weeks before they heal.
Cold sores are usually not treated with medication, because they go away on their own without treatment. However, if you have cold sores you want to avoid touching the sores and then rubbing your eyes, nose or other parts of your body. The sores are contagious and can spread to other people as well. It is important to avoid touching infants after you have had contact with a cold sore. Over-the-counter topical medications are available for cold sores to reduce symptoms by numbing the area. Antiviral medications taken orally may shorten the healing time for a cold sore, but these medications have to be started as early as possible to have an effect. Antiviral medicaitons may be prescribed by a doctor if a person experiences complications due to a herpes simplex virus infection.