What is a Cold Sore?
A cold sore (herpes labialis), occasionally called a fever blister, is a viral infection of the skin, commonly affecting the lips or other areas of the face.
Caused by the herpes simplex virus, it is characterized by a sore blister, preceded by a tingling or burning sensation. This contagious virus is often contracted before the age of 20 years, as a result of close contact with an infected person. (1)
Following primary infection, the body usually builds immunity to the virus. In fact, antibodies for the herpes simplex virus are found in about 80 percent of all adolescents. (2)
The cause of a cold sore is the herpes simplex virus. There are, however, factors that can trigger a recurrence after the initial infection. We will examine the virus in more detail and also look at some of the triggers.
Herpes Simplex Virus Type 1 (HSV-1)
This contagious virus is often contracted via contact with an infected person.
HSV-1 enters through the skin and reproduces in nerve cells, the skin’s surface and lower layers of the skin. The virus also passes to the root of the sensory nerve cells, where it lays dormant until triggered, activating the cold sore.
When activated, a cold sore can appear on the lips, mouth, face, nose or eyes. The first signs of infection appear two to 20 days following contact. Contact could be from kissing, sharing eating utensils and sharing towels.
After initial infection, the time the virus remains dormant can vary. It can recur anywhere from one to six times a year. Each time the cold sore reappears, the symptoms are generally less severe and don’t last as long as the previous outbreak. (3)
During initial infection, the whole mouth can be affected by the cold sore. However, repeat infections in this area tend to affect only the hard palate or lips. (4)
HSV-1 can also be transmitted to the genital area, although a recurrence in this area is unlikely. (5)
Herpes Simplex Virus Type 2 (HSV-2)
This strain of the virus enters, and lays dormant in the skin, in the same way as HSV-1. However, it is more prevalent in the genital area. It can, however, be transmitted to the facial area after oral sex, and cause a cold sore.
HSV-2 is likely to be recurrent in the genital area, but will rarely re-affect the facial area. (6, 7)
The causes of a cold sore can be due to the following contributory factors:
Demands on everyday life affect us all in many ways; we worry about work, partnerships, money or any number of other problems. These stressors not only impact on our emotional state, but also on the equilibrium of our immune system.
Consequently, our bodies’ ability to deal with infections and illnesses can be reduced. The result, in respect of a cold sore, is a reactivation of the virus, which leads to an outbreak. (8)
Many people report a recurrence of a cold sore when exposed to sunlight. UVB rays from the sun are known to reactivate the dormant HSV-1 virus.
One study has shown that applying sunscreen before exposure can reduce the incidence of a light induced cold sore. (9)
Extremes in Temperature
Very high or low temperatures can affect the immune system. Consequently, the ability to repress reactivation of the herpes simplex virus could be impaired, causing an outbreak. (10)
As well as sun exposure, tanning beds and lamps also emit damaging UV rays. UV radiation suppresses the immune system, which allows the virus to reactivate and cause a cold sore. (11, 12).
Damage to the skin, like a cut on the lip or or an abrasion while shaving, can result in the recurrence of a cold sore. (13)
The immune system is the body’s defence mechanism against bacteria, viruses and germs. When it does not work properly, we are susceptible to illness and infection.
A suppressed immune system can be caused by many factors,including: age, medication, malnutrition or diseases. When it is not working efficiently, the herpes simplex virus is more likely to resurrect itself and cause a cold sore. (14)
Hormonal changes in our bodies, whether due to stress or – in women – menstruation, pregnancy or menopause, can all affect the HSV virus.
At times of hormonal change, we are likely to be more vulnerable. (15)
Dental work could involve anything from a filling, root canal treatment, to removal of a tooth. Interference with the nerves in the mouth may reactivate the herpes simplex virus and result in a cold sore. (16)
Of all people infected with the herpes simplex virus, only about 30 percent will develop the blisters we associate with this condition.
The first time you are infected, you are likely to experience: fever, swollen glands in the neck, a sore throat or sore mouth. You might also find a cold sore appearing within two to twelve days from initial exposure of the infection.
The symptoms of the cold sore can be broken down into stages by days: (17)
This happens before a cold sore appears and is felt as a burning, tingling or itching sensation under the skin. This will usually be around the mouth area or beneath the nose.
Between days two and three, you may experience the first visible signs of an outbreak of a cold sore. This will be seen as fluid-filled blisters.
Ulcer or Weeping Stage
By day four, the most contagious period is reached. Blisters will become painful and rupture, resulting in a red, shallow, open sore
Days five to eight see the blisters dry up and become covered in a brownish or yellow scab. Although this scab will eventually fall off, try to prevent it from cracking or breaking.
Days nine to twelve see scabs become fewer and smaller, eventually allowing skin to heal completely and often leaving no scar.
In some cases, complications can result from a cold sore, particularly if the immune system is impaired. Some examples are:
HSV-1 and HSV-2 can both spread to the fingertips. This condition is called herpetic whitlow and consists of burning, itching and/or tingling of the affected finger. This sensation can spread across the hand and up the arm.
Following this, you might see redness and formation of a blister, accompanied by pain. (18)
The virus can be spread to the eye, causing infection and inflammation of the cornea. (keratitis). Scarring and injury as a result of repeated infection could lead to vision impairment or blindness. (19)
This skin condition is quite rare but can happen in children or adults who suffer from eczema, psoriasis or contact dermatitis. Untreated, this can become a medical emergency.
Blisters will appear on top of the affected skin and can become widespread across the body. Fever, fatigue and swollen glands may also be present. (20)
There are many over the counter medications which are effective in treating a cold sore. For this reason, most people will consult a pharmacist to obtain treatment.
If you are concerned about your cold sore, or find it is not healing, you should visit your doctor.
Diagnosis is normally straightforward, with examination of the cold sore. The doctor might take a swab of the blister for laboratory analysis, to confirm the presence of the virus.
Your hands and eyes may also be examined, to make sure that the virus has not spread and affected those areas.
What is a cold sore? A cold sore (herpes labialis), occasionally called fever blister, is a viral infection of the skin, commonly affecting the lips or other areas of the face.
What causes a cold sore? A cold sore is caused by infection with the herpes simplex virus.
How do doctors test for a cold sore? Diagnosis is usually via a visual examination. However, swabs can be taken and laboratory tested for confirmation of the presence of the herpes simplex virus.
When should you go to the doctors with a cold sore? If the cold sore is persistent, large or painful, this might require medical intervention. A weakened immune system as a result of treatments such as chemotherapy, or conditions like diabetes, should also be addressed. (21)
Can you prevent a cold sore? When blisters are present, avoid skin to skin contact with other people. Don’t share items like water bottles, lip balm, eating utensils, towels or food. Be mindful of where you are putting your hands when you have blisters; you don’t want to spread the virus. Also be sure to wash your hands frequently.
What can relieve a cold sore? There are many over the counter medications that can help relieve a cold sore. Moisturizing lip balms may help keep the lips from cracking; pain relieving gels or creams will reduce discomfort.
What are the complications of a cold sore? We have mentioned that HSV-1 and HSV-2 are contagious. Complications can arise if they are transferred to the eyes or affect other skin conditions.
Are there any natural remedies for a cold sore? If stress triggers a cold sore, relaxation techniques may help reduce recurrences. A topically applied cream containing rhubarb and sage has also shown to be an effective treatment. (22)
A cold sore is a contagious, viral infection of the skin, commonly affecting the lips and face. Whilst there is no cure for this condition, it is managed quickly and easily with over the counter or prescribed medication.
Prevention of a recurrence is possible, especially if you know what triggers your outbreak. It is also prudent to be considerate of others and avoid personal contact when you have a cold sore.