Herpes simplex virus

Also called gingivostomatitis

Herpes simplex is a virus that causes oral herpes or cold sores around the mouth or face, and genital herpes. The virus is often known as HSV for short.

There are two types of HSV:

  1. HSV type 1 most commonly causes cold sores, but it can also cause genital herpes.
  2. HSV type 2 is the usual cause of genital herpes, but it can also infect the mouth.

The virus is shed in saliva and genital secretions, both during a clinical attack and for some days or weeks afterwards. The amount shed from active lesions is 100 to 1000 times greater than when it is inactive. Spread is by direct contact with infected secretions.

The HSV invades the outer layer of the skin, (the epidermis) sometimes resulting in fluid-filled blisters to appear. From here, it travels along the nerve paths to the nerve roots where it lies dormant (or asleep) and can waken, causing a recurrence from time to time.

The initial infection

When a person is infected with herpes for the first time, the episode is called a primary infection. Symptoms vary from none at all through to moderate discomfort. This first outbreak starts 1–3 weeks after the virus has invaded the skin and subsides within a few weeks.

An outbreak has 4 stages:

  1. a tingling feeling in the skin
  2. slight swelling and then development of a number of fluid-filled blisters, which are often painful
  3. the blisters burst and form clusters, leaving fluid-filled sores
  4. the sores eventually dry, scab over and heal without scarring after 8 to 10 days.

The virus can spread until the sores are completely covered by scabs. Once healed, the virus can still be shed (or passed onto someone else), but the risk is much lower.

If sores develop inside the mouth, as well as outside, it is often called gingivostomatitis. This should be treated with antiviral medicine and pain relief as sores and blisters lining the mouth and throat make it harder to eat and drink and take longer to heal, lasting up to 14 days.

Herpes simplex can also cause infection in other places such as:

  • Herpetic whitlow – small red blisters or tender lumps on fingers and hands.
  • Scrum pox – facial blisters in a rugby player from direct contact.
  • Suckling infant with mouth sores.


The virus remains hidden in the nerves for the rest of the person's life and becomes active again from time to time.  Triggers can include a fever (eg, a common cold), UV radiation (exposure to sunlight), extreme tiredness or lowered immune function. Some people have regular outbreaks or recurrences, while others have none. With time, these  become less frequent.


When someone has an episode of herpes, either facial or genital, they should consider themselves infectious from the start of the episode to the healing of the last ulcer. During this time the virus can be transmitted to other people and, in rare cases, can be transferred to other areas of the body.

To help prevent spread, you should avoid:

  • Kissing anyone or sharing drinking utensils when you have a cold sore present.
  • Having oral sex when you or your partner have facial or genital sores.
  • Sharing towels and face flannels.
  • Using saliva to wet contact lenses if you have sores around your mouth.
  • Sunburn – apply sunscreen to face and sunscreen lip balm to your lips.

Also, ensure you wash your hands before attending to young children and babies.

Learn more

Herpes – the key facts NZ Herpes Foundation

Credits: Health Navigator Editorial Team.