Learn more about the causes, symptoms, treatment and prevention of this common lip sore caused by the herpes simplex virus type 1 (HSV-1).
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.
Illustration of cold sore on different skin colors. A cold sore is a cluster of fluid-filled blisters. Healing often occurs in two to three weeks without scarring. Cold sores are sometimes called fever blisters.
A cold sore usually passes through several stages:
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:
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.
Cold sores generally clear up without treatment. See your health care provider if:
Cold sores are caused by certain strains of the herpes simplex virus (HSV). HSV-1 usually causes cold sores. HSV-2 is often the cause of genital herpes. But either type can spread to the face or genitals through close contact, such as kissing or oral sex. Shared eating utensils, razors and towels can also spread HSV-1.
Cold sores are most likely to spread when you have oozing blisters. But you can spread the virus even if you don't have blisters. Many people who are infected with the virus that causes cold sores never develop symptoms.
Once you've had a herpes infection, the virus can hide in nerve cells in the skin and may cause another cold sore at the same place as before. A return of cold sores may be triggered by:
Almost everyone is at risk of cold sores. Most adults carry the virus that causes cold sores, even if they've never had symptoms.
You're most at risk of complications from the virus if you have a weak immune system from conditions and treatments such as:
In some people, the virus that causes cold sores can cause problems in other areas of the body, including:
Your health care provider may prescribe an antiviral medicine for you to take on a regular basis if you develop cold sores more than nine times a year or if you're at high risk of serious complications. If sunlight seems to trigger your condition, apply sunblock to the spot where the cold sore tends to form. Or talk with your health care provider about using an oral antiviral medicine before you do an activity that tends to cause a cold sore to return.
Take these steps to help avoid spreading cold sores to other people:
Your health care provider can usually diagnose cold sores just by looking at them. To confirm the diagnosis, your health care provider might take a sample from the blister for testing in a laboratory.
Cold sores often clear up without treatment in 2 to 4 weeks. Your doctor might prescribe antiviral medicine that may speed the healing process. Examples include:
Some of these products are pills. Others are creams you put on the sores several times a day. In general, the pills work better than the creams. For very severe infections, some antiviral medicines can be injected.
The cold sore ointment docosanol (Abreva) may shorten the healing time of a cold sore. At the first sign of symptoms, apply it to the affected skin as directed on the package. Use a cotton-tipped swab to put medicine on a cold sore. This helps prevent the spread of the sores to other parts of the body.
To ease the discomfort of a cold sore:
Studies about whether alternative medicine helps with cold sores have had mixed results. Some approaches that people use for cold sores include:
Cold sores often clear up without treatment in 2 to 4 weeks. Make an appointment with your primary care provider if your cold sores:
Before your appointment, you may want to list answers to the following questions:
Below are some basic questions to ask your health care provider about cold sores.
Your health care provider is likely to ask you a few questions. Being ready to answer them may reserve time to go over any points you want to talk about in-depth. Your health care provider may ask: