Cold sores are small, painful, fluid-filled blisters or sores that appear on the lips, mouth, or nose that are caused by a virus. The sores can be painful and usually last a few days.

Cold sores are small and painful blisters that can appear around the mouth, face, or nose. They are sometimes referred to as fever blisters, and they're caused by herpes simplex virus type 1 (HSV-1). Kids can get cold sores by kissing or sharing eating utensils with an infected person.

Usually, HSV-1 cause cold sores in the mouth or face, and herpes simplex virus type 2 (HSV-2) causes lesions in the genital area, resulting in genital herpes. But sometimes, HSV-1 can cause genital lesions as well, especially if someone has received oral sex from an infected partner.

Colds sores in the mouth are very common, and many kids get infected with HSV-1 during the preschool years. The sores usually go away on their own within about a week.

Symptoms

Most kids who get cold sores get infected by eating or drinking from the same utensils as someone who is infected with the herpes virus or by getting kissed by an infected adult. The cold sores first form blisters on the lips and inside the mouth. The blisters then become sores. In some cases, the gums become red and swollen. In other cases, the virus also leads to a fever, muscle aches, eating difficulties, a generally ill feeling, irritability, and swollen neck glands. These symptoms can last up to 2 weeks.

After a child is initially infected, the virus can lie dormant without causing any symptoms. But it can reactivate later, typically after some sort of stress like a cold, an infection, hormonal change, menstrual periods, or even before a big test at school. If the virus is reactivated it can cause tingling and numbness around the mouth and a blister.

Treatment

Cold sores from HSV-1 usually go away on their own within 5 to 7 days. Although no medications can make the infection go away, some treatments are available that can shorten the length of the outbreak and make the cold sores less painful.

Cool foods and drinks can help relieve discomfort, and acetaminophen may also ease the pain. Aspirin should not be given to kids with viral infections since it has been associated with Reye syndrome.

Call the doctor if your child:

• has another health condition that has weakened the immune system, which could allow the HSV infection to spread and cause problems in other parts of the body
• has sores that don't heal by themselves within 7 to 10 days
• has any sores near the eyes
• gets cold sores frequently

Since the virus that causes cold sores is so contagious, it's important to prevent it from spreading to other family members. Precautions to take with kids who have cold sores include:

• keeping their drinking glasses and eating utensils separate from those used by other family members and washing these items thoroughly after use
• teaching them not to kiss others until the sores heal
• having them wash their hands frequently and as soon as possible after touching the cold sores
• trying to keep them from touching their eyes — if HSV infects the eyes, it can be very serious

If you're caring for a child with a cold sore, you also should be diligent about washing your hands frequently so that you don't contract the virus or spread it to others.