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What are Cold Sores?

Cold sores are tiny, fluid-filled blisters often found in patches on or around the lips. They are caused by a viral infection and are highly contagious, but not usually serious.

What are the Causes of Cold Sores?

Cold sores are usually caused by HSV-1, a type of herpes simplex virus. The virus quickly spreads through contact with infected body fluids. It can be transferred by close contact through kissing, sharing utensils, razors, and towels. 

Factors that trigger cold sores include:

  • Viral infection or fever
  • Hormonal changes, such as those associated with menstruation
  • Stress
  • Fatigue
  • Exposure to sunlight and wind
  • Changes in the immune system
  • Injury to the skin

What are the Symptoms of Cold Sores?

Depending on whether this is your first outbreak or a recurrence, the signs and symptoms will differ. In most cases, a cold sore goes through the following stages:

  • Many experience itching, burning or tingling around the lips before a small and hard painful patch forms and blisters erupt.
  • The blisters are small and usually emerge along the lip's edge. They may also appear around the nose, on the cheekbones, or inside the mouth.
  • The blisters then grow, merge together, and break, leaving shallow open wounds that discharge fluid and then crust over.
  • Later the skin heals, and the crusts or scabs fall off. 

After the initial exposure to the virus, symptoms of a cold sore might take up to 20 days to appear. In a first-time outbreak, you may also experience:

  • Fever
  • Headache 
  • Sore throat
  • Muscle aches
  • Painful gums
  • Swollen lymph nodes

Diagnosis of Cold Sores

If you’ve had a cold sore before, you'll be familiar with the symptoms. Cold sores are commonly diagnosed by your doctor by simple observation. A sample may be obtained from the blister for laboratory testing to confirm the diagnosis.

What are the Treatments for Cold Sores?

Cold sores generally heal in 2 to 4 weeks without treatment. Several forms of antiviral drugs can help treat the condition. These include the following:

  • Over-the-counter Medications: Creams or ointments that you apply directly to the cold sore can be purchased without a prescription. If you start using these creams as soon as you sense tingling or itching, you can sometimes prevent the cold sores from forming.
  • Oral antiviral Medicine: An antiviral medicine that you take orally may be prescribed by your doctor.
  • Intravenous (IV) antiviral Medicine: To treat persistent infections, your doctor may need to prescribe an antiviral drug that is administered intravenously. In this case, your doctor will monitor your treatment.


To prevent cold sores from spreading to other persons or other regions of your body, the following measures are recommended:

  • While blisters are present, avoid kissing and skin contact with others.
  • Avoid sharing items like utensils, towels, lip balm, and other personal items.
  • Wash your hands carefully before touching other people - especially babies, who can develop a severe infection.