What is Herpes Labialis?

Herpes labialis or oral herpes is an infection of the mouth area that causes small, painful blisters to develop on the lips, gums or throat. These blisters are caused by the herpes simplex virus, a common and highly contagious virus that infects most people in the U.S by time they reach the age of 20.

There are three stages of infection that occur in oral herpes, which include the primary infection, the latency period and recurrence. During the initial stage of infection, the virus enters the skin or mucosal membrane, where it then reproduces. Blisters and other symptoms such as fever may develop, although the virus sometimes does not cause any symptoms.

After primary infection, the virus lies dormant inside the nervous tissue of the spine where it reproduces but remains inactive. Later in life, the virus can reactivate, particularly in cases of emotional or physical distress, and lead to the development of further sores and symptoms. When this occurs, a person is said to have recurrent oral herpes. Recurrent herpes is not a serious condition, but many people use over-the-counter treatments to relieve their symptoms, which usually resolve within a few weeks. In some people, the cold sores recur around two or three times every year, while other people only experience a cold sore once and never again. In general, recurrent infections lead to milder symptoms than primary infection.


Symptoms do not present immediately after infection with herpes simplex virus and cold sores usually emerge within one to three weeks after initial contact with the virus. People typically experience a tingling or burning sensation around areas of the mouth, which is followed by the appearance of small blisters, usually at the edge of the lower lip. Fever, sore throat, sore lymph nodes in the neck, painful swallowing and muscle aches may also manifest. Usually, symptoms occur in children aged between 1 and 5 years, although they can affect people of any age and at any time. The symptoms of oral herpes usually last for up to three weeks.

When many blisters develop, the term “outbreak” may be used and the patient may present with any of the following:

  • Red blisters that burst and leak
  • Many small blisters that grow together to form one large blister
  • Small blisters containing clear or yellowish fluid
  • A crusty, yellow blister

Causes of herpes labialis

Herpes labialis is so named because the cold sore typically affects the lips. The infection is usually caused by herpes simplex virus type 1 (HSV-1) but occasionally herpes simplex virus type 2 (HSV-2) is responsible. The HSV-2 infection is usually transmitted through having oral sex with someone who has a genital herpes infection. In genital herpes, painful blisters develop in and around the groin.

The herpes virus is spread easily and people can catch the virus if they have close personal contact with an infected individual or if they touch objects on which the virus may be present such as towels, razors, dishes or other items that may get shared.

Once the virus lays dormant inside nerve cells, certain events can increase the likelihood of recurrence. Examples of these events include:

  • Fatigue
  • Menstruation
  • Weak immune system
  • Hormonal changes
  • Stress
  • Exposure to strong sunlight
  • Exposure to extreme temperatures
  • Fever
  • Dental surgery
  • Upper respiratory infection

Treatment of herpes labialis

Cold sores usually resolve independently within ten days of onset, but antiviral creams can be bought over the counter to help ease symptoms and accelerate healing. However, these creams tend to be expensive and often only relieve symptoms for between a few hours and one day. Cold sore patches containing hydrocolloid gel can also help to heal skin wounds.

For severe cases of herpes labialis, antiviral tablets may be prescribed and examples include acclovir, famciclovir and valacyclovir.These antiviral agents are more effective if they are taken as soon as symptoms first present (e.g. when tingling is felt around the mouth) and before the blisters first appear. However, these medications cannot cure oral herpes and it is still possible for the patient to spread the virus to those around them.

Some examples of self-help measures people can take to alleviate their symptoms include the following:

  • Washing the blisters with antiseptic soap and water to help prevent spread of the virus to other areas of the body
  • Applying ice to the blisters to help relieve pain
  • Avoiding hot drinks and spicy or salty foods
  • Gargling with cool water
  • Rinsing with salt water
  • Taking pain killers

Long-term Outlook

Although symptoms after initial infection usually resolve within three weeks, recurrence can occur on a frequent basis. However, the severity and frequency of the recurring symptoms usually diminish as people age. Infections that occur in immuno-compromised individuals can be severe and these people should seek medical advice if they develop oral herpes.

Further Reading

Last Updated: Jun 10, 2023

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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