Also called, fever blisters or oral herpes, cold sores are quite common, affecting 600,000 new people  each year in the U.S. Cold sores cause red, painful blisters on the mouth, lips and each sore is filled with fluid. They also are known to cause fever and swollen glands with the first outbreak, especially. 

So what actually causes cold sores? The herpes simplex type 1 (HSV-1) virus causes cold sores. The virus is spread though contact with a person who has the virus by kissing or sharing towels, utensils, or razors. They usually pop up (literally) about a week after you're exposed to the virus. Some people even have tingling or burning sensations on the area 1 to 2 days before the blister appears. Most cases result in cold sores healing within about 2 weeks without leaving a scar. Once you've been exposed to the virus, you can get the sores again. 

Stress, fatigue, and being sick can bring cold sores on again and for women during their menstrual cycle. Most sores don't need any treatment but some ointments can help relieve symptoms. For patients who have repeat outbreaks, a physician may prescribe medication, especially if they get very sick. 

To help prevent getting or spreading old sores:

• Don’t kiss people when you have cold sores.
• Don’t share towels, lip balm, utensils, or other personal items when you have cold sores.
• Wash your hands often when you have cold sores, especially before touching another person.
• Avoid touching other parts of your body after touching your cold sore, especially your eyes and genital area.
• Try to avoid the things that trigger your cold sores, such as stress or tiredness.
• Use sunscreen to help prevent getting cold sores from sun exposure.

If you get a cold sore, there are home remedies you can try to relieve the symptoms. 

• Use over-the-counter pain relievers to help reduce pain.
• Use warm or cold compresses to help relieve pain.
• Don’t pick at the blisters.