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Cold Sores

Cold sores are caused by the Herpes simplex virus

What are cold sores?

Cold sores are small, fluid-filled blisters that occur as red, swollen areas of skin. They usually occur on the lips, but may also be found around the mouth or near the nostrils. Any similar looking blister on other areas of the body will not usually be termed a cold sore.

A cold sore can make the area in which it occurs tender and painful and can sometimes lead to irritation and swelling of the gums.

Cold sores are caused by a very common virus known as the herpes simplex virus (HSV). There are two strains of viruses:

  • Herpes Simplex Type 1 (HSV-1)
  • Herpes Simplex Type 2 (HSV-2)

The strain that causes cold sores is HSV-1. HSV-2 may also cause cold sores but this is rare as this strain mainly causes genital herpes.

Picking up a cold sore

HSV-1, the virus causing cold sores, can only be transmitted during close personal contact such as kissing. What is not commonly known, however, is that cold sore viruses are usually passed on in early childhood.

Often, between the ages of 3 and 5, cold sore viruses are transferred from parents or family members, but do not cause infection. The viruses then lie dormant or inactive and later in life, these viruses become active, giving rise to cold sores.

The recurrence of cold sores

After entering the body, cold sore viruses tend to remain in your body for the rest of your life. Most of the time, they will exist in a dormant state and if you keep your immune system strong, these viruses will not lead to the formation of cold sores.

However, any weakening of the body’s defences (or immune system) can bring about a reactivation of the virus and the return of a cold sore.

Many triggers are known to cause outbreaks of cold sores. These include:

  • emotional or psychological stress
  • injuries to the affected area
  • fatigue and tiredness
  • menstruation
  • exposure to sunlight
  • infections such as the cold or flu
  • other types of illness


Cold sores are recurrent and the virus can activate many times. The first cold sore infection, known as the primary infection, produces different symptoms to subsequent infections.

Primary Infection of cold sores

The first infection of a cold sore does not always include the typical appearance of cold sores! Symptoms of this primary infection often appear as a 'normal' cold or flu and can include:

  • swollen glands
  • a sore throat
  • excess production of saliva
  • fever
  • dehydration
  • headaches
  • nausea

Secondary Infection of cold sores

These are subsequent or recurrent infections of cold sores. Usually, they are less severe and last a shorter period of time. In most cases, the only symptom is an outbreak of cold sores around the mouth. Sometimes, swollen glands may be noticed.

The outbreak of a cold sore usually starts with an itching or tingling sensation. This is then followed by the appearance of small blisters. After a few days, these blisters dry up and scabs form.


In general, there is no treatment that can permanently remove a cold sore virus from the body. Cold sores usually clear up without any treatment within two weeks and rarely leave scarring.

There are however, a number of ways you can treat cold sores. These range from conventional medicines to natural herbal remedies:

  • Some people find painkillers such as paracetamol or ibuprofen can ease pain or discomfort
  • There are also anti-viral over-the-counter creams and liquids which may be used to help treat a cold sore
  • If the infection is severe, your GP may prescribe anti-viral medication taken orally
  • Echinacea has been shown to have an anti-viral effect against cold sore viruses
  • Propolis based cold sore treatments have been popular for many years

Do not touch cold sores. Wash hands thoroughly to prevent spreading infection. Avoid close personal contact with others who have cold sores, and do not share items that may have been in contact with the virus such as lipstick or face cloths. To prevent scabs or scars resulting from a cold sore, keep the skin soft with moisturisers


There are a number of ways to lower your risk of picking up or passing on a cold sore and to prevent recurrence. However, it has to be said that triggers for the cold sore virus may differ from person to person:

  • Use a sun-block (above SPF15) on lips to prevent over exposure to sunlight, which tends to trigger cold sores
  • Good hand hygiene stops the spread of infection of cold sore viruses
  • A good sleep pattern and a healthy diet can improve the body's defences and in turn, help prevent cold sores

Complications of cold sores

Cold sores rarely lead to complications and in most cases, the infection will clear up within two weeks. However some possible complications are:

  • Cold sores becoming infected by secondary bacteria
  • Cold sore viruses spreading to the eyes and affecting vision
  • Cold sores spreading to the genitals and causing genital herpes
  • Cold sore viruses spreading into skin that may be already damaged or broken (eg. from eczema) and causing a skin infection.