Cold sore (Herpes labialis)

Herpes labialis, also known as cold sores or fever blisters, is a widespread viral disease caused by the herpes simplex virus type 1 (HSV type 1). The virus manifests itself in the form of small, weeping blisters on the lips, which can often be sensitive, painful or itchy.

Normally, herpes labialis clears up on its own after a while. Nevertheless, there is a risk of a new outbreak.

There are two types of the herpes simplex virus (HSV):

• HSV type 1 represents the most common type. As a rule, this type of virus only occurs on the mouth and lips (herpes labialis).
• HSV type 2 is mainly restricted to the genitals (genital herpes).

Both virus types can spread to the skin, mucous membranes, nervous system and internal organs (rarely). The infection is widespread but only rarely has a severe course.

Among adults, more than 95 percent carry the type 1 virus; HSV type 2 is carried by 10 to 30 percent. However, these numbers do not tell us how many people actually have an outbreak of cold sores. It can also often happen that the virus is completely asymptomatic. The majority of people become infected with HSV 1 during childhood, with HSV2 the infection usually happens after puberty.

The causative agent of herpes labialis (cold sore) is the herpes simplex virus type 1 (HSV type 1). The virus is transmitted from person to person in several ways:

• Droplet infection, such as when coughing, sneezing, and talking.
• Direct contact, for example when kissing
• Smear infection, for example when sharing a drinking glass

The first contact with HSV type 1 usually occurs in childhood between the ages of three and five. The incubation period is approximately two to twelve days. Generally, only one percent of cases can be expected to show typical symptoms of the disease. The rest of the infections have a symptomless or inconspicuous course.

If herpes labialis occurs, the cells attack the uppermost skin layer where weeping blisters develop. Starting from the epidermis, the viruses travel along the nerve tracts to the nerve roots (ganglia). At this point, the virus remains in an inactive state and waits until the immune system is weakened. If this state occurs, the virus breaks out again by migrating along the nerve pathways to the skin surface where it forms vesicles again (reactivation).

The following factors can trigger a reactivation of cold sores:

• Infectious diseases accompanied by fever (herpes febrilis).
• UV radiation (herpes solaris)
• Hormonal (for example due to pregnancy) and psychological factors (e.g. stress)
• Immunodeficiency (e.g. due to certain medications or HIV infection)
• Injuries About 75 percent of all people suffer from the recurring occurrence of herpes labialis.

If the first contact with herpes labialis occurs in childhood, the infection often runs without symptoms. However, labial herpes can also occur in the form of oral thrush (gingivostomatitis herpetica). The characteristics here are:

• mouth rash with very painful blisters
• Fever
• Swelling of the lymph nodes
• General feeling of illness

If these symptoms subside, the virus can reappear at a later time and cause herpes labialis. The first symptoms are itching and a feeling of tension on the affected skin area. In rare cases, pain can also occur. Subsequently, small weeping blisters appear, which mainly form on the lips and around the mouth. However, they can also occur on the rest of the facial skin, preferably on the cheeks, nostrils and earlobes. Viral infection of the eyes is also not excluded.

As a rule, the blisters disappear after eight to ten days, leaving a crust.

Based on the medical history and the typical appearance of the blisters, the doctor can easily diagnose herpes labialis.

If there is still doubt, a smear test can provide certainty by detecting the antigen.

To determine the corresponding antibodies, the doctor takes a blood sample. However, this only makes sense in the case of a first infection with herpes viruses, as 95 percent of all adults have already developed antibodies against the virus.

Medical treatment of herpes labialis is only necessary if the symptoms are very pronounced. Only the symptoms can be treated, but not the cause.

Local therapy is carried out in the form of disinfectant additives with which the blisters are brushed. Antiviral ointments, which prevent the viruses from multiplying, serve the same purpose. However, these ointments are only effective if they are applied within two to three days of the first symptoms appearing.

If the course of herpes labialis is severe or there are complications, antiviral tablets (virustatics) or injections may have to be administered. If the affected person suffers from fever or other accompanying symptoms, a doctor should be consulted. In addition to the treatment of herpes labialis, possible concomitant diseases should be excluded.

Normally, no further complications result from herpes labialis. The blisters disappear within a few days without scarring.

The course of the disease is different in people with a weakened immune system (for example, after chemotherapy or in HIV patients). If the therapy is carried out at an early stage, there is a better chance of a positive healing process.

Herpes labialis can cause the following complications:

• Herpes labialis in its most severe form with organ infestation (e.g. pneumonia).
• The eyes can also be affected by the virus. Infection of the cornea (herpes corneae) can lead to impaired vision.
• Disruption of the facial nerves, which can result in (usually temporary) paralysis (facial paresis).
• Meningitis, as well as inflammation of the brain (encephalitis), which can have a potentially life-threatening course.
• Children may suffer from a very severe outbreak of herpes if their skin is already affected by eczema (such as atopic dermatitis).
• Wound infections caused by bacteria (bacterial superinfection): In this case, medication against the virus and the bacteria (e.g. antibiotics) must be used.
• Poorly healing inflammations of the skin and mucous membrane, which can result in tissue death, as well as severe conjunctivitis of the eye and other severe courses of disease in HIV patients.

An intact immune system is crucial to prevent herpes labialis. This can be strengthened by a healthy lifestyle, balanced diet, exercise and sufficient sleep.

These measures contribute to the prevention of labial herpes or its (re)occurrence:

• When exposed to strong sunlight (such as glacier sun), creams with a high sun protection factor should be applied to lips and around the mouth. So-called sun-blocker pastes have a particularly high effect.
• The risk of infection should be kept as low as possible by not touching the blisters with the hands. This also prevents transmission to other parts of the body.
• Regular hand washing should be observed. This is especially true if you have come into contact with blisters.
• Contact with babies should be avoided if possible, as infection with the viruses can lead to encephalitis.

If the risk of infection is particularly high for some people who have not yet come into contact with the virus, there is the possibility of an indication vaccination. This is particularly advisable for women of childbearing age, tumour patients and medical staff.