Key Points about Cold Sores

  • A cold sore, or oral herpes, is a viral infection that causes small, fluid-filled bumps on the lips.
  • Cold sores are contagious, and can spread through saliva and skin-to-skin contact.
  • Once infected with the herpes simplex virus (HSV-1), people may experience cold sores whenever the dormant virus becomes active.
  • Cold sores can be triggered by factors such as stress, sleep deprivation, and sun exposure.
  • Most cold sores resolve on their own within a few weeks.
Common related conditions
Skin Abscess


Cold sores, or oral herpes, are small, fluid-filled bumps on the lips. They are caused by an infection with a herpes simplex virus (HSV-1). Cold sores are contagious, and can spread through skin-to-skin contact such as kissing, or through sharing drinks.

The majority of people are carriers of HSV-1. This means that the virus remains dormant in peoples’ bodies until it is triggered, and produces a cold sore. Common triggers for cold sores include stress, sleep deprivation, and sunlight.

While most cold sores go away on their own within a few weeks, some cases may require medical attention. Call your doctor if your cold sores do not go away on their own, or occur often.

Cold sore causes

Most cold sores are caused by the herpes simplex virus HSV-1, although some are caused by HSV-2, which is the virus that usually leads to genital herpes.

After the initial infection, HSV-1 remains in your skin’s nerve cells, inactive. While the majority of people who have been infected with HSV-1 do not experience any symptoms, some people do. In these people, when the virus is re-activated, cold sores emerge.

The virus that causes cold sores can spread from person to person at any time, although transmission is most likely to occur when the affected person has a current cold sore outbreak. Cold sores can spread through:

  • Kissing or touching
  • Sharing items such as razors, towels, lip balm and eating utensils
  • Oral sex

Cold sore risk factors

If you are part of the majority of people carrying the HSV-1 virus, your cold sores may be triggered by:

  • Sunlight
  • Stress
  • Sleep deprivation
  • Illnesses, including viral infections
  • Hormone fluctuations

Cold sore symptoms

When you have a cold sore, you may experience:

  • An itching or tingling feeling in the affected area at the beginning of an outbreak
  • Red, itchy sores or blisters on or around the lips
  • Blisters that scab over after bursting and releasing pus

Cold sores may last for a few days to a week, and take up to several weeks to disappear completely. If you develop a subsequent cold sore in the same area in the future, your symptoms will likely be milder than they were during the previous outbreak.

Cold sore complications

The virus that causes cold sores can lead to additional infections, in some cases, such as in:

  • The fingertips — HSV-1 or HSV-2 infection in the fingertips is also called herpes whitlow.
  • The eyes — Eye infections that occur often can cause impaired vision.
  • Large patches of skin —If you suffer from eczema, your cold sores could spread across the body to areas affected by the eczema.
  • Additional organs — like the brain and spinal cord, for example. Other-organ infection with HSV-1 or HSV-2 is more likely to occur in people who are immunocompromised.

Cold sore prevention

If you experience cold sores, you can attempt to prevent recurrences by avoiding the factors that trigger them for you. This may involve:

  • Managing stress
  • Getting enough sleep
  • Applying sunscreen to areas where your cold sores often appear

If you have an active cold sore, you can prevent it from spreading to others by:

  • Avoiding direct skin contact with other people, in the area where you are affected
  • Using your own items such as lip balm and cups, and not sharing them with other people
  • Practicing good hand hygiene

Cold sore diagnosis

Your doctor will usually diagnose cold sores though a visual examination of the area.

Cold sore treatment

Most cold sores disappear on their own within a few weeks. If you consult a doctor about your cold sores, you may be prescribed an antiviral drug to quicken recovery.

When to seek care

While most cold sores heal on their own, there are some cases that may need medical attention. Call your doctor if:

  • You are immunocompromised
  • Your cold sores are still present after two weeks
  • Your cold sores occur frequently, and are particularly irritating
  • You develop eye irritation while you have a cold sore

Next Steps

For people with cold sores that occur repeatedly and often, or who are at an increased risk of developing complications from cold sores, doctors may prescribe an antiviral to be taken regularly.

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