Herpes simplex virus – HSV or oral herpes

HSV (herpes) is the virus that causes painful blisters located on the lips, gums, tongue, roof of the mouth, inside the cheeks and sometimes on the face and neck.

It can also trigger symptoms such as fever and muscle pain.

These blisters, once they burst, are covered with a yellow crust, which peels off after a week.

People usually confuse this cold sore with canker sore.

Canker sores are located only inside the mouth, on the tongue and roof of the mouth, not on other skin surfaces.

Although they occur quite often, they are not contagious, are well defined and are not followed by other complications.

The appearance of thrush is caused by various substances that irritate the oral mucosa or by local micro-trauma. (toothbrush injury, bitten tongue or cheek, irritating enamel plugs, ill-fitting dental or prosthetic work).

Mouth ulcers occur most often in children aged 1-2 years, but can affect people of any age and at any time of the year (Herpetic gingivostomatitis).

Now back to herpes. There are two types of oral herpes (HSV):

HSV-1 and HSV-2.

Although they are similar in structure, they are distinct serological and genetic entities. Both cause oral (blister) and genital lesions.

However, HSV-1 (oral herpes) causes 80% of all oral lesions and only 20% of genital lesions, while HSV-2 causes the opposite (80% genital and 20% oral).

HSV-1 occurs only in humans.

HSV-1 can be transmitted by touching infected saliva, contact with infected mucous membranes or skin. Because the virus is highly contagious, most people are infected with at least one subtype of herpes before they reach adulthood.

Once the virus is contacted by a person it has a unique three-stage course:

Primary infection

The virus enters the skin or mucous membranes through small cracks and then reproduces. At this stage, oral lesions and other symptoms such as fever appear.

In some cases, the virus causes neither lesions nor symptoms, which is why the person concerned is unaware of its existence. This is called asymptomatic infection.

Asymptomatic infection is twice as common as infection with symptoms.


From the infected areas, the virus retreats into the nerve cells to the spinal ganglia.

There the virus reproduces again, usually without any symptoms, and becomes inactive until reactivated in the body by certain conditions.


When people face emotionally or physically stressful situations, the virus reactivates and causes new signs and symptoms.

The following factors contribute to the virus’s recurrence:

  • stress (mental or physical)

  • UV rays

  • fever

  • fatigue

  • hormonal changes (e.g. menstruation)

  • immune system suppression

  • damage to a nerve region where a previous HSV infection has occurred.


Herpes simplex virus is a DNA type of virus that also causes lesions around the mouth.

This virus enters the body through small cracks or cuts in the injured skin or mucous membranes through contact with an infected person (whether or not the lesions are visible).

Simply touching a person infected with oral herpes is the main mode of transmission.

Oral and genital lesions recur over time because the virus exists in the body but remains dormant in nerve cells.

One of the ways the herpes simplex virus multiplies in human cells is by taking over the nucleus of the cells and changing its structure.

It is the modified nucleus that provides information and helps to diagnose HSV infections by microscopic examination.

The vesicle eruption occurs following the maturation of HSV particles that rupture the human cell membrane.

Signs and symptoms

Incubation period – in the case of HSV-1 the time period between contact with the virus and the appearance of symptoms is 2-12 days (on average 4-5 days).

Period of disease manifestation – signs and symptoms will last two to three weeks. Usually these are: fever, fatigue, muscle aches, irritability.

Many patients, before the appearance of sores or blisters have reported: pain, burning, tingling or itching at the site of infection.

The blisters that appear break easily and resemble small, superficial, greyish-white ulcers with a red base. A few days later, a yellowish crust appears over them.

The oral lesions can be very painful and eating and drinking will be difficult.

Sores may be located on the gums, throat, lips, front of the tongue, inside the cheeks and roof of the mouth – lesions may also extend to the lower chin or throat.

The gums become inflamed, red and may bleed

Throat lymph nodes often swell and become painful

People under the age of 20 may develop unpleasant ulcerations of the tonsils.

When does a visit to the doctor become urgent?

Because herpes lesions are often painful, many people have difficulty consuming food or fluids. To prevent dehydration, it is advisable to consult a doctor if these processes cannot be carried out properly.

Symptoms that suggest dehydration are:

  • oliguria – decreased urine output

  • drowsiness

  • irritability

  • xerostomia

A doctor should be notified if a person is unsure of the type of oral lesions (they may belong to other more serious diseases than oral herpes).

If an infant younger than 6 weeks has blisters, the doctor should be consulted.

Severe complications and infections occur especially in infants. For example, in addition to pain inside the oral cavity, HSV-1 can also affect brain function.

People whose immune system is weakened should notify their doctor if they develop such lesions, as they may develop into severe infections or complications of the disease may occur.

Pregnant women should consult their doctor immediately if they notice symptoms specific to vaginal HSV infection, especially if the pregnancy is close to term.

When to go to hospital?

Signs and symptoms of dehydration are warning signs that require an urgent visit to hospital.

Infants, especially those under 6 weeks of age, should consult their paediatrician or be taken to a hospital emergency room if they develop blisters in the oral cavity or if they have oliguria or are consuming fewer fluids.


The doctor will make a presumptive diagnosis based on information provided by the patient and the physical examination.

The characteristic appearance of herpes simplex virus-specific wounds helps to make the diagnosis easy. Further investigations are usually not necessary.

In certain situations, in order to determine the exact type of the condition, the doctor may require the following laboratory tests to be carried out:

  • taking a sample (tissue or fluid) from the lesions to identify the virus

  • viral culture

  • Tzanck smear for cytodiagnosis (which will show changes in the cell nucleus caused by HSV)

  • antigen and antibody analysis (serological and PCR tests to determine whether the infection is caused by HSV-1 or HSV-2, whether it is acute or chronic).


The following measures can be taken for self-care at home:

  • acetaminophen or ibuprofen should be used for muscle pain and to reduce fever. (Acetaminophen can trigger asthma in children, so seek medical advice before giving it to children)

  • drink plenty of fluids to prevent dehydration

  • avoid physical contact with the lesions and any discharge from them.

Medical treatment includes:

  • use of antipyretics and adequate hydration

  • local application of anesthetic to relieve pain in blisters or oral lesions

  • in general, oral medication is not recommended for people with a normal immune system, but only for children under 6 weeks of age or people suffering from severe diseases.

Hospital admission is necessary in the following cases:

  • the local infection is severe

  • the infection has spread to other organ systems

  • people who have a weakened immune system

  • dehydrated people requiring intravenous hydration

  • infants younger than 6 weeks

mild, uncomplicated herpes simplex rashes do not require any treatment. For severe infections, oral antiviral drugs are useful:

  • acyclovir

  • valacyclovir

  • famciclovir

Acyclovir and penciclovir ointment can also shorten the duration of recurrent HSV-1 attacks if applied topically before lesions develop. These drugs can stop viral replication but do not eliminate HSV from the body or prevent possible relapses. They are also often used for HSV-2 infections.

Other measures useful to a person who has herpes simplex are:

  • Avoid dehydration by drinking plenty of fluids

  • Use pain relief medication only on the advice of a doctor

  • If the first symptoms of dehydration appear, seek emergency medical attention.

Prevention methods

To reduce the risk of being infected with HSV-1, avoid touching the saliva, skin and mucous membranes of people with oral herpes lesions. Protection against genital herpes can be done by using latex condoms, although protection is not 100% guaranteed in this case either.

Do not kiss people who have oral herpes in the acute phase.

Do not use the same cutlery, towels, razor blades, etc.

If you have touched your own herpes, wash your hands.


The lesions and symptoms of oral herpes usually disappear completely within two to three weeks, without any scarring. However, manifestations may recur in stressful situations.


  • atopic eczema

  • encephalitis

  • keratoconjunctivitis

  • pharyngitis

  • hepatitis

  • panaritium (finger blisters).

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