Oral Herpes

Medically Reviewed by Robert Brennan on March 22, 2023
Written by WebMD Editorial Contributors
5 min read

Oral herpes is an infection caused by the herpes simplex virus. The virus causes painful sores on your lips, gums, tongue, roof of your mouth, and inside your cheeks. It also can cause symptoms such as fever and muscle aches.

  • The herpes simplex virus affects only humans. Mouth sores most commonly occur in children aged 1-2 years, but they can affect people at any age and any time of the year.
  • People contract herpes by touching infected saliva, mucous membranes, or skin. Because the virus is highly contagious, most people have been infected by at least 1 herpes subtype before adulthood.
  • After the herpes virus infects you, it has a rather unique ability to proceed to 3 stages.
    • Primary infection: The virus enters your skin or mucous membrane and reproduces. During this stage, oral sores and other symptoms, such as fever, may develop.
      • The virus may not cause any sores and symptoms. You may not know that you have it. This is called asymptomatic infection.
      • Asymptomatic infection occurs twice as often as the disease with symptoms.
  • Latency: From the infected site, the virus moves to a mass of nervous tissue in your spine called the dorsal root ganglion. There the virus reproduces again and becomes inactive.
  • Recurrence: When you encounter certain stresses, emotional or physical, the virus may reactivate and cause new sores and symptoms.

Herpes simplex is a DNA virus that causes sores in and around your mouth. Two herpes subtypes may cause these sores.

  • Herpes simplex virus, type 1 or herpes-1, which causes 80% of cases of oral herpes infections
  • Herpes simplex virus, type 2 or herpes-2, which causes the rest
  • Incubation period: For oral herpes, the amount of time between contact with the virus and the appearance of symptoms, the incubation period, is 2-12 days. Most people average about 4 days.
  • Duration of illness: Signs and symptoms will last 2-3 weeks. Fever, tiredness, muscle aches, and irritability may occur.
    • Pain, burning, tingling, or itching occurs at the infection site before the sores appear. Then clusters of blisters erupt. These blisters break down rapidly and, when seen, appear as tiny, shallow, gray ulcers on a red base. A few days later, they become crusted or scabbed and appear drier and more yellow
  • Oral sores: The most intense pain caused by these sores occurs at the onset and make eating and drinking difficult.
    • The sores may occur on the lips, the gums, the front of the tongue, the inside of the cheeks, the throat, and the roof of the mouth.
    • They may also extend down the chin and neck.
    • The gums may become mildly swollen and red and may bleed.
  • Neck lymph nodes often swell and become painful.
  • In people in their teens and 20s, herpes may cause a painful throat with shallow ulcers and a grayish coating on the tonsils.

When to call the doctor

  • Because the sores are painful, you may have difficulty eating or drinking. To prevent dehydration, call your doctor as soon as you cannot eat or drink.
  • Call your doctor immediately if any of these symptoms, which suggest dehydration, occur:
    • A decrease in urination (fewer wet diapers in infants)
    • Drowsiness
    • Irritability
    • Dry mouth
  • Call your doctor if you or your children are not sure what the sores are.
  • If your child is younger than 8 weeks, notify your doctor when sores appear. Severe infection or disease complications occur more commonly in infants. For instance, besides affecting the mouth, the herpes simplex virus may go to the brain and produce damage.
  • People whose immune systems are weakened should also call their doctor when sores appear. Your immune system protects you from infection or fights infection. If your system is weakened, you are more likely to have severe infection or disease complication.

When to go to the hospital

Signs and symptoms of dehydration may warrant going to a hospital's emergency department.

A doctor will base a diagnosis on information you provide and on physical examination. The characteristic appearance of the herpes sores leaves little doubt. Further testing is usually not necessary.

If you require a definitive diagnosis, for instance, if your infection involves other organ systems, the doctor may conduct laboratory tests.

  • A sample from the sores to identify the virus
  • A culture analysis
  • A staining test called the Tzanck smear
  • Antigen and antibody studies
  • Blood sampling for antibody studies

Treatment includes medication for fever and taking plenty of fluids.

  • A topical anesthetic such as viscous lidocaine (Dilocaine, Nervocaine, Xylocaine, Zilactin-L) may be prescribed to relieve pain.
  • Oral or IV medication does exist for herpes but is not recommended for people with a normal immune system. It is used only for people with weakened immune systems, infants younger than 6 weeks, or people with severe disease.
  • Some people may require hospital admission:
    • Those with severe local infection
    • People whose infection has spread to other organ systems
    • People with weakened immune systems
    • Dehydrated individuals who need IV hydration
    • Infants younger than 6 weeks
  • Drink plenty of fluids.
  • Use pain medications as instructed by the doctor.
  • Use medications to control fever.
  • Watch for signs and symptoms of dehydration.

Avoid touching saliva, skin, or mucous membranes that have sores.

The sores and symptoms of oral herpes completely clear up in 2-3 weeks. But the sores may reappear under certain stressful situations.

Media file 1: Oral Herpes. Clusters of blisters erupt on the lips, tongue, and inside the mouth. Most people have been infected by at least 1 herpes subtype before adulthood.

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