Overview
Cold sores, or fever blisters, are a common viral infection. They are tiny, fluid-filled blisters on and around the lips. These blisters are often grouped together in patches. After the blisters break, a scab forms that can last several days. Cold sores usually heal in 2 to 3 weeks without leaving a scar.
Cold sores spread from person to person by close contact, such as kissing. They’re usually caused by herpes simplex virus type 1 (HSV-1), and less commonly herpes simplex virus type 2 (HSV-2). Both of these viruses can affect the mouth or genitals and can be spread by oral sex. The virus can spread even if you don’t see the sores.
There’s no cure for cold sores, but treatment can help manage outbreaks. Prescription antiviral medicine or creams can help sores heal more quickly. And they may make future outbreaks happen less often and be shorter and less serious.
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Symptoms
A cold sore usually passes through several stages:
- Tingling and itching. Many people feel itching, burning or tingling around the lips for a day or so before a small, hard, painful spot appears and blisters form.
- Blisters. Small fluid-filled blisters often form along the border of the lips. Sometimes they appear around the nose or cheeks or inside the mouth.
- Oozing and crusting. The small blisters may merge and then burst. This can leave shallow open sores that ooze and crust over.
Symptoms vary, depending on whether this is your first outbreak or a recurrence. The first time you have a cold sore, symptoms may not start for up to 20 days after you were first exposed to the virus. The sores can last several days. And the blisters can take 2 to 3 weeks to heal completely. If blisters return, they’ll often appear at the same spot each time and tend to be less severe than the first outbreak.
In a first-time outbreak, you also might experience:
- Fever.
- Painful gums.
- Sore throat.
- Headache.
- Muscle aches.
- Swollen lymph nodes.
Children under 5 years old may have cold sores inside their mouths. These sores are often mistaken for canker sores. Canker sores involve only the mucous membrane and aren’t caused by the herpes simplex virus.
When to see a doctor
Cold sores generally clear up without treatment. See your health care provider if:
- You have a weak immune system.
- The cold sores don’t heal within two weeks.
- Symptoms are severe.
- The cold sores often return.
- You have gritty or painful eyes.
