Cold sores

Also known as facial herpes simplex

Cold sores are small fluid-filled blisters that appear on the skin, usually on the lips, chin, cheeks, or in the nostrils. Some people have no symptoms from the infection; others develop painful and unsightly cold sores that last for a week or more.

Key points

  1. Cold sores are caused by infection with the herpes simplex virus.
  2. Infection is very common and easily passed from person to person by close personal contact.
  3. Cold sores usually occur on the lips, chin, cheeks, or in the nostrils. Occasionally, they occur inside the mouth on the gums or roof of the mouth.
  4. A burning sensation is often present just before the skin lesions develop.
  5. Medicines can relieve some of the pain and discomfort associated with the sores.

Causes

Cold sores are due to infection with the herpes simplex virus (HSV).

  • HSV-1, the most common type, which usually causes facial herpes and 50% of genital herpes through oral to genital contact.
  • HSV-2, which usually causes genital herpes and occasionally facial herpes.

Facial herpes is spread by close physical contact. Most people will have come into contact with the virus between the ages of three and five (for example, through being kissed or hugged by a relative who has the virus), but only one in three of these will have a first episode with symptoms.

What does the virus do?

The HSV invades the outer layer of the skin (the epidermis), resulting in fluid-filled blisters to appear. From here, it travels along the nerve paths to the trigeminal ganglion, a bundle of nerves close to the inner ear, where it lies dormant. 

Symptoms

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 one to three weeks after the virus has invaded the skin and subsides within a few weeks.

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.

Recurrences

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.

An outbreak has four 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 and the infection will usually be external.

Prevention

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
  • wash your hands before attending to young children and babies
  • sunburn – apply sunblock to face and lip balm to your lips.

Treatment

For more people with just one or two blisters on their lip or near their nose, keeping it clean, dry and leaving it alone are all that is needed.

  • Wash your hands before and after touching the cold sore, or applying cream to the cold sore.
  • Take care not to touch the cold sore, then touch or rub your eyes. Take extra care if you wear contact lenses.
  • Do not share cosmetics such as lipsticks.
  • Do not pick off any scabs – this may cause infection or scarring.
  • Antiviral skin creams can be tried but are expensive and may only shorten the outbreak by a few hours to a day.
  • Ice, held against the blisters or a warm wash cloth may help ease any pain.
  • If you have blisters in your mouth, try gargling with cool water or eating ice blocks.
  • Rinse your mouth with salt water or a pain relieving mouthwash.
  • Take pain relief such as paracetamol or ibuprofen.
  • If blisters appear to be infected, apply antibacterial ointment (from your doctor).

Recurrent or severe infection

  • If recurrent or severe infection occurs, see your doctor – oral antiviral medicine may be needed.
  • Other underlying conditions may also need to be considered.
  • If you have any infection near the eye – see a doctor straight away. Eye infections can be serious.

Learn more

Facial herpes The New Zealand Herpes Foundation
Cold sores
 Medline Plus (USA)
Cold sores NHS Choices (UK)

Credits: Medline Plus, New Zealand Herpes Foundation. Latest update by Health Navigator, August 2016.